NOISSUE split GUI stuff from logic library

269 files changed, 33688 insertions, 0 deletions

diff --git a/libraries/gui/CMakeLists.txt b/libraries/gui/CMakeLists.txt
new file mode 100644
index 00000000..1551a927
--- /dev/null
+++ b/libraries/gui/CMakeLists.txt
@@ -0,0 +1,28 @@
+project(MultiMC_logic)
+
+set(GUI_SOURCES
+	DesktopServices.h
+	DesktopServices.cpp
+
+	# Icons
+	icons/MMCIcon.h
+	icons/MMCIcon.cpp
+	icons/IconList.h
+	icons/IconList.cpp
+
+	SkinUtils.cpp
+	SkinUtils.h
+)
+################################ COMPILE ################################
+
+add_library(MultiMC_gui SHARED ${GUI_SOURCES})
+set_target_properties(MultiMC_gui PROPERTIES CXX_VISIBILITY_PRESET hidden VISIBILITY_INLINES_HIDDEN 1)
+
+generate_export_header(MultiMC_gui)
+
+# Link
+target_link_libraries(MultiMC_gui iconfix MultiMC_logic)
+qt5_use_modules(MultiMC_gui Gui)
+
+# Mark and export headers
+target_include_directories(MultiMC_gui PUBLIC "${CMAKE_CURRENT_BINARY_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}")
diff --git a/libraries/gui/DesktopServices.cpp b/libraries/gui/DesktopServices.cpp
new file mode 100644
index 00000000..3154ea01
--- /dev/null
+++ b/libraries/gui/DesktopServices.cpp
@@ -0,0 +1,149 @@
+#include "DesktopServices.h"
+#include <QDir>
+#include <QDesktopServices>
+#include <QProcess>
+#include <QDebug>
+
+/**
+ * This shouldn't exist, but until QTBUG-9328 and other unreported bugs are fixed, it needs to be a thing.
+ */
+#if defined(Q_OS_LINUX)
+
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+template <typename T>
+bool IndirectOpen(T callable, qint64 *pid_forked = nullptr)
+{
+	auto pid = fork();
+	if(pid_forked)
+	{
+		if(pid > 0)
+			*pid_forked = pid;
+		else
+			*pid_forked = 0;
+	}
+	if(pid == -1)
+	{
+		qWarning() << "IndirectOpen failed to fork: " << errno;
+		return false;
+	}
+	// child - do the stuff
+	if(pid == 0)
+	{
+		// unset all this garbage so it doesn't get passed to the child process
+		qunsetenv("LD_PRELOAD");
+		qunsetenv("LD_LIBRARY_PATH");
+		qunsetenv("LD_DEBUG");
+		qunsetenv("QT_PLUGIN_PATH");
+		qunsetenv("QT_FONTPATH");
+
+		// open the URL
+		auto status = callable();
+
+		// detach from the parent process group.
+		setsid();
+
+		// die. now. do not clean up anything, it would just hang forever.
+		_exit(status ? 0 : 1);
+	}
+	else
+	{
+		//parent - assume it worked.
+		int status;
+		while (waitpid(pid, &status, 0))
+		{
+			if(WIFEXITED(status))
+			{
+				return WEXITSTATUS(status) == 0;
+			}
+			if(WIFSIGNALED(status))
+			{
+				return false;
+			}
+		}
+		return true;
+	}
+}
+#endif
+
+namespace DesktopServices {
+bool openDirectory(const QString &path, bool ensureExists)
+{
+	qDebug() << "Opening directory" << path;
+	QDir parentPath;
+	QDir dir(path);
+	if (!dir.exists())
+	{
+		parentPath.mkpath(dir.absolutePath());
+	}
+	auto f = [&]()
+	{
+		return QDesktopServices::openUrl(QUrl::fromLocalFile(dir.absolutePath()));
+	};
+#if defined(Q_OS_LINUX)
+	return IndirectOpen(f);
+#else
+	return f();
+#endif
+}
+
+bool openFile(const QString &path)
+{
+	qDebug() << "Opening file" << path;
+	auto f = [&]()
+	{
+		return QDesktopServices::openUrl(QUrl::fromLocalFile(path));
+	};
+#if defined(Q_OS_LINUX)
+	return IndirectOpen(f);
+#else
+	return f();
+#endif
+}
+
+bool openFile(const QString &application, const QString &path, const QString &workingDirectory, qint64 *pid)
+{
+	qDebug() << "Opening file" << path << "using" << application;
+#if defined(Q_OS_LINUX)
+	// FIXME: the pid here is fake. So if something depends on it, it will likely misbehave
+	return IndirectOpen([&]()
+	{
+		return QProcess::startDetached(application, QStringList() << path, workingDirectory);
+	}, pid);
+#else
+	return QProcess::startDetached(application, QStringList() << path, workingDirectory, pid);
+#endif
+}
+
+bool run(const QString &application, const QStringList &args, const QString &workingDirectory, qint64 *pid)
+{
+	qDebug() << "Running" << application << "with args" << args.join(' ');
+#if defined(Q_OS_LINUX)
+	// FIXME: the pid here is fake. So if something depends on it, it will likely misbehave
+	return IndirectOpen([&]()
+	{
+		return QProcess::startDetached(application, args, workingDirectory);
+	}, pid);
+#else
+	return QProcess::startDetached(application, args, workingDirectory, pid);
+#endif
+}
+
+bool openUrl(const QUrl &url)
+{
+	qDebug() << "Opening URL" << url.toString();
+	auto f = [&]()
+	{
+		return QDesktopServices::openUrl(url);
+	};
+#if defined(Q_OS_LINUX)
+	return IndirectOpen(f);
+#else
+	return f();
+#endif
+}
+
+}
diff --git a/libraries/gui/DesktopServices.h b/libraries/gui/DesktopServices.h
new file mode 100644
index 00000000..9daf192a
--- /dev/null
+++ b/libraries/gui/DesktopServices.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <QUrl>
+#include <QString>
+#include "multimc_gui_export.h"
+
+/**
+ * This wraps around QDesktopServices and adds workarounds where needed
+ * Use this instead of QDesktopServices!
+ */
+namespace DesktopServices
+{
+	/**
+	 * Open a file in whatever application is applicable
+	 */
+	MULTIMC_GUI_EXPORT bool openFile(const QString &path);
+
+	/**
+	 * Open a file in the specified application
+	 */
+	MULTIMC_GUI_EXPORT bool openFile(const QString &application, const QString &path, const QString & workingDirectory = QString(), qint64 *pid = 0);
+
+	/**
+	 * Run an application
+	 */
+	MULTIMC_GUI_EXPORT bool run(const QString &application,const QStringList &args, const QString & workingDirectory = QString(), qint64 *pid = 0);
+
+	/**
+	 * Open a directory
+	 */
+	MULTIMC_GUI_EXPORT bool openDirectory(const QString &path, bool ensureExists = false);
+
+	/**
+	 * Open the URL, most likely in a browser. Maybe.
+	 */
+	MULTIMC_GUI_EXPORT bool openUrl(const QUrl &url);
+};
diff --git a/libraries/gui/SkinUtils.cpp b/libraries/gui/SkinUtils.cpp
new file mode 100644
index 00000000..f69a1071
--- /dev/null
+++ b/libraries/gui/SkinUtils.cpp
@@ -0,0 +1,47 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "SkinUtils.h"
+#include "net/HttpMetaCache.h"
+#include "Env.h"
+
+#include <QFile>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+
+namespace SkinUtils
+{
+/*
+ * Given a username, return a pixmap of the cached skin (if it exists), QPixmap() otherwise
+ */
+QPixmap getFaceFromCache(QString username, int height, int width)
+{
+	QFile fskin(ENV.metacache()
+					->resolveEntry("skins", username + ".png")
+					->getFullPath());
+
+	if (fskin.exists())
+	{
+		QPixmap skin(fskin.fileName());
+		if(!skin.isNull())
+		{
+			return skin.copy(8, 8, 8, 8).scaled(height, width, Qt::KeepAspectRatio);
+		}
+	}
+
+	return QPixmap();
+}
+}
diff --git a/libraries/gui/SkinUtils.h b/libraries/gui/SkinUtils.h
new file mode 100644
index 00000000..29dcd6a6
--- /dev/null
+++ b/libraries/gui/SkinUtils.h
@@ -0,0 +1,25 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QPixmap>
+
+#include "multimc_gui_export.h"
+
+namespace SkinUtils
+{
+QPixmap MULTIMC_GUI_EXPORT getFaceFromCache(QString id, int height = 64, int width = 64);
+}
diff --git a/libraries/gui/icons/IconList.cpp b/libraries/gui/icons/IconList.cpp
new file mode 100644
index 00000000..99def3b7
--- /dev/null
+++ b/libraries/gui/icons/IconList.cpp
@@ -0,0 +1,381 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "IconList.h"
+#include <FileSystem.h>
+#include <QMap>
+#include <QEventLoop>
+#include <QMimeData>
+#include <QUrl>
+#include <QFileSystemWatcher>
+#include <QSet>
+#include <QDebug>
+
+#define MAX_SIZE 1024
+
+IconList::IconList(QString builtinPath, QString path, QObject *parent) : QAbstractListModel(parent)
+{
+	// add builtin icons
+	QDir instance_icons(builtinPath);
+	auto file_info_list = instance_icons.entryInfoList(QDir::Files, QDir::Name);
+	for (auto file_info : file_info_list)
+	{
+		QString key = file_info.baseName();
+		addIcon(key, key, file_info.absoluteFilePath(), MMCIcon::Builtin);
+	}
+
+	m_watcher.reset(new QFileSystemWatcher());
+	is_watching = false;
+	connect(m_watcher.get(), SIGNAL(directoryChanged(QString)),
+			SLOT(directoryChanged(QString)));
+	connect(m_watcher.get(), SIGNAL(fileChanged(QString)), SLOT(fileChanged(QString)));
+
+	directoryChanged(path);
+}
+
+void IconList::directoryChanged(const QString &path)
+{
+	QDir new_dir (path);
+	if(m_dir.absolutePath() != new_dir.absolutePath())
+	{
+		m_dir.setPath(path);
+		m_dir.refresh();
+		if(is_watching)
+			stopWatching();
+		startWatching();
+	}
+	if(!m_dir.exists())
+		if(!FS::ensureFolderPathExists(m_dir.absolutePath()))
+			return;
+	m_dir.refresh();
+	auto new_list = m_dir.entryList(QDir::Files, QDir::Name);
+	for (auto it = new_list.begin(); it != new_list.end(); it++)
+	{
+		QString &foo = (*it);
+		foo = m_dir.filePath(foo);
+	}
+	auto new_set = new_list.toSet();
+	QList<QString> current_list;
+	for (auto &it : icons)
+	{
+		if (!it.has(MMCIcon::FileBased))
+			continue;
+		current_list.push_back(it.m_images[MMCIcon::FileBased].filename);
+	}
+	QSet<QString> current_set = current_list.toSet();
+
+	QSet<QString> to_remove = current_set;
+	to_remove -= new_set;
+
+	QSet<QString> to_add = new_set;
+	to_add -= current_set;
+
+	for (auto remove : to_remove)
+	{
+		qDebug() << "Removing " << remove;
+		QFileInfo rmfile(remove);
+		QString key = rmfile.baseName();
+		int idx = getIconIndex(key);
+		if (idx == -1)
+			continue;
+		icons[idx].remove(MMCIcon::FileBased);
+		if (icons[idx].type() == MMCIcon::ToBeDeleted)
+		{
+			beginRemoveRows(QModelIndex(), idx, idx);
+			icons.remove(idx);
+			reindex();
+			endRemoveRows();
+		}
+		else
+		{
+			dataChanged(index(idx), index(idx));
+		}
+		m_watcher->removePath(remove);
+		emit iconUpdated(key);
+	}
+
+	for (auto add : to_add)
+	{
+		qDebug() << "Adding " << add;
+		QFileInfo addfile(add);
+		QString key = addfile.baseName();
+		if (addIcon(key, QString(), addfile.filePath(), MMCIcon::FileBased))
+		{
+			m_watcher->addPath(add);
+			emit iconUpdated(key);
+		}
+	}
+}
+
+void IconList::fileChanged(const QString &path)
+{
+	qDebug() << "Checking " << path;
+	QFileInfo checkfile(path);
+	if (!checkfile.exists())
+		return;
+	QString key = checkfile.baseName();
+	int idx = getIconIndex(key);
+	if (idx == -1)
+		return;
+	QIcon icon(path);
+	if (!icon.availableSizes().size())
+		return;
+
+	icons[idx].m_images[MMCIcon::FileBased].icon = icon;
+	dataChanged(index(idx), index(idx));
+	emit iconUpdated(key);
+}
+
+void IconList::SettingChanged(const Setting &setting, QVariant value)
+{
+	if(setting.id() != "IconsDir")
+		return;
+
+	directoryChanged(value.toString());
+}
+
+void IconList::startWatching()
+{
+	auto abs_path = m_dir.absolutePath();
+	FS::ensureFolderPathExists(abs_path);
+	is_watching = m_watcher->addPath(abs_path);
+	if (is_watching)
+	{
+		qDebug() << "Started watching " << abs_path;
+	}
+	else
+	{
+		qDebug() << "Failed to start watching " << abs_path;
+	}
+}
+
+void IconList::stopWatching()
+{
+	m_watcher->removePaths(m_watcher->files());
+	m_watcher->removePaths(m_watcher->directories());
+	is_watching = false;
+}
+
+QStringList IconList::mimeTypes() const
+{
+	QStringList types;
+	types << "text/uri-list";
+	return types;
+}
+Qt::DropActions IconList::supportedDropActions() const
+{
+	return Qt::CopyAction;
+}
+
+bool IconList::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column,
+							const QModelIndex &parent)
+{
+	if (action == Qt::IgnoreAction)
+		return true;
+	// check if the action is supported
+	if (!data || !(action & supportedDropActions()))
+		return false;
+
+	// files dropped from outside?
+	if (data->hasUrls())
+	{
+		auto urls = data->urls();
+		QStringList iconFiles;
+		for (auto url : urls)
+		{
+			// only local files may be dropped...
+			if (!url.isLocalFile())
+				continue;
+			iconFiles += url.toLocalFile();
+		}
+		installIcons(iconFiles);
+		return true;
+	}
+	return false;
+}
+
+Qt::ItemFlags IconList::flags(const QModelIndex &index) const
+{
+	Qt::ItemFlags defaultFlags = QAbstractListModel::flags(index);
+	if (index.isValid())
+		return Qt::ItemIsDropEnabled | defaultFlags;
+	else
+		return Qt::ItemIsDropEnabled | defaultFlags;
+}
+
+QVariant IconList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	int row = index.row();
+
+	if (row < 0 || row >= icons.size())
+		return QVariant();
+
+	switch (role)
+	{
+	case Qt::DecorationRole:
+		return icons[row].icon();
+	case Qt::DisplayRole:
+		return icons[row].name();
+	case Qt::UserRole:
+		return icons[row].m_key;
+	default:
+		return QVariant();
+	}
+}
+
+int IconList::rowCount(const QModelIndex &parent) const
+{
+	return icons.size();
+}
+
+void IconList::installIcons(QStringList iconFiles)
+{
+	for (QString file : iconFiles)
+	{
+		QFileInfo fileinfo(file);
+		if (!fileinfo.isReadable() || !fileinfo.isFile())
+			continue;
+		QString target = FS::PathCombine(m_dir.dirName(), fileinfo.fileName());
+
+		QString suffix = fileinfo.suffix();
+		if (suffix != "jpeg" && suffix != "png" && suffix != "jpg" && suffix != "ico")
+			continue;
+
+		if (!QFile::copy(file, target))
+			continue;
+	}
+}
+
+bool IconList::iconFileExists(QString key)
+{
+	auto iconEntry = icon(key);
+	if(!iconEntry)
+	{
+		return false;
+	}
+	return iconEntry->has(MMCIcon::FileBased);
+}
+
+const MMCIcon *IconList::icon(QString key)
+{
+	int iconIdx = getIconIndex(key);
+	if (iconIdx == -1)
+		return nullptr;
+	return &icons[iconIdx];
+}
+
+bool IconList::deleteIcon(QString key)
+{
+	int iconIdx = getIconIndex(key);
+	if (iconIdx == -1)
+		return false;
+	auto &iconEntry = icons[iconIdx];
+	if (iconEntry.has(MMCIcon::FileBased))
+	{
+		return QFile::remove(iconEntry.m_images[MMCIcon::FileBased].filename);
+	}
+	return false;
+}
+
+bool IconList::addIcon(QString key, QString name, QString path, MMCIcon::Type type)
+{
+	// replace the icon even? is the input valid?
+	QIcon icon(path);
+	if (!icon.availableSizes().size())
+		return false;
+	auto iter = name_index.find(key);
+	if (iter != name_index.end())
+	{
+		auto &oldOne = icons[*iter];
+		oldOne.replace(type, icon, path);
+		dataChanged(index(*iter), index(*iter));
+		return true;
+	}
+	else
+	{
+		// add a new icon
+		beginInsertRows(QModelIndex(), icons.size(), icons.size());
+		{
+			MMCIcon mmc_icon;
+			mmc_icon.m_name = name;
+			mmc_icon.m_key = key;
+			mmc_icon.replace(type, icon, path);
+			icons.push_back(mmc_icon);
+			name_index[key] = icons.size() - 1;
+		}
+		endInsertRows();
+		return true;
+	}
+}
+
+void IconList::reindex()
+{
+	name_index.clear();
+	int i = 0;
+	for (auto &iter : icons)
+	{
+		name_index[iter.m_key] = i;
+		i++;
+	}
+}
+
+QIcon IconList::getIcon(QString key)
+{
+	int icon_index = getIconIndex(key);
+
+	if (icon_index != -1)
+		return icons[icon_index].icon();
+
+	// Fallback for icons that don't exist.
+	icon_index = getIconIndex("infinity");
+
+	if (icon_index != -1)
+		return icons[icon_index].icon();
+	return QIcon();
+}
+
+QIcon IconList::getBigIcon(QString key)
+{
+	int icon_index = getIconIndex(key);
+
+	if (icon_index == -1)
+		key = "infinity";
+
+	// Fallback for icons that don't exist.
+	icon_index = getIconIndex(key);
+
+	if (icon_index == -1)
+		return QIcon();
+
+	QPixmap bigone = icons[icon_index].icon().pixmap(256,256).scaled(256,256);
+	return QIcon(bigone);
+}
+
+int IconList::getIconIndex(QString key)
+{
+	if (key == "default")
+		key = "infinity";
+
+	auto iter = name_index.find(key);
+	if (iter != name_index.end())
+		return *iter;
+
+	return -1;
+}
+
+//#include "IconList.moc"
diff --git a/libraries/gui/icons/IconList.h b/libraries/gui/icons/IconList.h
new file mode 100644
index 00000000..971db824
--- /dev/null
+++ b/libraries/gui/icons/IconList.h
@@ -0,0 +1,85 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QMutex>
+#include <QAbstractListModel>
+#include <QFile>
+#include <QDir>
+#include <QtGui/QIcon>
+#include <memory>
+#include "MMCIcon.h"
+#include "settings/Setting.h"
+#include "Env.h" // there is a global icon list inside Env.
+
+#include "multimc_logic_export.h"
+
+class QFileSystemWatcher;
+
+class MULTIMC_LOGIC_EXPORT IconList : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	explicit IconList(QString builtinPath, QString path, QObject *parent = 0);
+	virtual ~IconList() {};
+
+	QIcon getIcon(QString key);
+	QIcon getBigIcon(QString key);
+	int getIconIndex(QString key);
+
+	virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
+	virtual int rowCount(const QModelIndex &parent = QModelIndex()) const;
+
+	bool addIcon(QString key, QString name, QString path, MMCIcon::Type type);
+	bool deleteIcon(QString key);
+	bool iconFileExists(QString key);
+
+	virtual QStringList mimeTypes() const;
+	virtual Qt::DropActions supportedDropActions() const;
+	virtual bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column,
+							  const QModelIndex &parent);
+	virtual Qt::ItemFlags flags(const QModelIndex &index) const;
+
+	void installIcons(QStringList iconFiles);
+
+	const MMCIcon * icon(QString key);
+
+	void startWatching();
+	void stopWatching();
+
+signals:
+	void iconUpdated(QString key);
+
+private:
+	// hide copy constructor
+	IconList(const IconList &) = delete;
+	// hide assign op
+	IconList &operator=(const IconList &) = delete;
+	void reindex();
+
+public slots:
+	void directoryChanged(const QString &path);
+
+protected slots:
+	void fileChanged(const QString &path);
+	void SettingChanged(const Setting & setting, QVariant value);
+private:
+	std::shared_ptr<QFileSystemWatcher> m_watcher;
+	bool is_watching;
+	QMap<QString, int> name_index;
+	QVector<MMCIcon> icons;
+	QDir m_dir;
+};
diff --git a/libraries/gui/icons/MMCIcon.cpp b/libraries/gui/icons/MMCIcon.cpp
new file mode 100644
index 00000000..6b4eef39
--- /dev/null
+++ b/libraries/gui/icons/MMCIcon.cpp
@@ -0,0 +1,89 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MMCIcon.h"
+#include <QFileInfo>
+
+MMCIcon::Type operator--(MMCIcon::Type &t, int)
+{
+	MMCIcon::Type temp = t;
+	switch (t)
+	{
+	case MMCIcon::Type::Builtin:
+		t = MMCIcon::Type::ToBeDeleted;
+		break;
+	case MMCIcon::Type::Transient:
+		t = MMCIcon::Type::Builtin;
+		break;
+	case MMCIcon::Type::FileBased:
+		t = MMCIcon::Type::Transient;
+		break;
+	default:
+	{
+	}
+	}
+	return temp;
+}
+
+MMCIcon::Type MMCIcon::type() const
+{
+	return m_current_type;
+}
+
+QString MMCIcon::name() const
+{
+	if (m_name.size())
+		return m_name;
+	return m_key;
+}
+
+bool MMCIcon::has(MMCIcon::Type _type) const
+{
+	return m_images[_type].present();
+}
+
+QIcon MMCIcon::icon() const
+{
+	if (m_current_type == Type::ToBeDeleted)
+		return QIcon();
+	return m_images[m_current_type].icon;
+}
+
+void MMCIcon::remove(Type rm_type)
+{
+	m_images[rm_type].filename = QString();
+	m_images[rm_type].icon = QIcon();
+	for (auto iter = rm_type; iter != Type::ToBeDeleted; iter--)
+	{
+		if (m_images[iter].present())
+		{
+			m_current_type = iter;
+			return;
+		}
+	}
+	m_current_type = Type::ToBeDeleted;
+}
+
+void MMCIcon::replace(MMCIcon::Type new_type, QIcon icon, QString path)
+{
+	QFileInfo foo(path);
+	if (new_type > m_current_type || m_current_type == MMCIcon::ToBeDeleted)
+	{
+		m_current_type = new_type;
+	}
+	m_images[new_type].icon = icon;
+	m_images[new_type].changed = foo.lastModified();
+	m_images[new_type].filename = path;
+}
diff --git a/libraries/gui/icons/MMCIcon.h b/libraries/gui/icons/MMCIcon.h
new file mode 100644
index 00000000..6f9617c2
--- /dev/null
+++ b/libraries/gui/icons/MMCIcon.h
@@ -0,0 +1,55 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QString>
+#include <QDateTime>
+#include <QIcon>
+
+#include "multimc_gui_export.h"
+
+struct MULTIMC_GUI_EXPORT MMCImage
+{
+	QIcon icon;
+	QString filename;
+	QDateTime changed;
+	bool present() const
+	{
+		return !icon.isNull();
+	}
+};
+
+struct MULTIMC_GUI_EXPORT MMCIcon
+{
+	enum Type : unsigned
+	{
+		Builtin,
+		Transient,
+		FileBased,
+		ICONS_TOTAL,
+		ToBeDeleted
+	};
+	QString m_key;
+	QString m_name;
+	MMCImage m_images[ICONS_TOTAL];
+	Type m_current_type = ToBeDeleted;
+
+	Type type() const;
+	QString name() const;
+	bool has(Type _type) const;
+	QIcon icon() const;
+	void remove(Type rm_type);
+	void replace(Type new_type, QIcon icon, QString path = QString());
+};
diff --git a/libraries/logic/AbstractCommonModel.cpp b/libraries/logic/AbstractCommonModel.cpp
new file mode 100644
index 00000000..71d75829
--- /dev/null
+++ b/libraries/logic/AbstractCommonModel.cpp
@@ -0,0 +1,133 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "AbstractCommonModel.h"
+
+BaseAbstractCommonModel::BaseAbstractCommonModel(const Qt::Orientation orientation, QObject *parent)
+	: QAbstractListModel(parent), m_orientation(orientation)
+{
+}
+
+int BaseAbstractCommonModel::rowCount(const QModelIndex &parent) const
+{
+	return m_orientation == Qt::Horizontal ? entryCount() : size();
+}
+int BaseAbstractCommonModel::columnCount(const QModelIndex &parent) const
+{
+	return m_orientation == Qt::Horizontal ? size() : entryCount();
+}
+QVariant BaseAbstractCommonModel::data(const QModelIndex &index, int role) const
+{
+	if (!hasIndex(index.row(), index.column(), index.parent()))
+	{
+		return QVariant();
+	}
+	const int i = m_orientation == Qt::Horizontal ? index.column() : index.row();
+	const int entry = m_orientation == Qt::Horizontal ? index.row() : index.column();
+	return formatData(i, role, get(i, entry, role));
+}
+QVariant BaseAbstractCommonModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	if (orientation != m_orientation && role == Qt::DisplayRole)
+	{
+		return entryTitle(section);
+	}
+	else
+	{
+		return QVariant();
+	}
+}
+bool BaseAbstractCommonModel::setData(const QModelIndex &index, const QVariant &value, int role)
+{
+	const int i = m_orientation == Qt::Horizontal ? index.column() : index.row();
+	const int entry = m_orientation == Qt::Horizontal ? index.row() : index.column();
+	const bool result = set(i, entry, role, sanetizeData(i, role, value));
+	if (result)
+	{
+		emit dataChanged(index, index, QVector<int>() << role);
+	}
+	return result;
+}
+Qt::ItemFlags BaseAbstractCommonModel::flags(const QModelIndex &index) const
+{
+	if (!hasIndex(index.row(), index.column(), index.parent()))
+	{
+		return Qt::NoItemFlags;
+	}
+
+	const int entry = m_orientation == Qt::Horizontal ? index.row() : index.column();
+	if (canSet(entry))
+	{
+		return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+	}
+	else
+	{
+		return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+	}
+}
+
+void BaseAbstractCommonModel::notifyAboutToAddObject(const int at)
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		beginInsertColumns(QModelIndex(), at, at);
+	}
+	else
+	{
+		beginInsertRows(QModelIndex(), at, at);
+	}
+}
+void BaseAbstractCommonModel::notifyObjectAdded()
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		endInsertColumns();
+	}
+	else
+	{
+		endInsertRows();
+	}
+}
+void BaseAbstractCommonModel::notifyAboutToRemoveObject(const int at)
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		beginRemoveColumns(QModelIndex(), at, at);
+	}
+	else
+	{
+		beginRemoveRows(QModelIndex(), at, at);
+	}
+}
+void BaseAbstractCommonModel::notifyObjectRemoved()
+{
+	if (m_orientation == Qt::Horizontal)
+	{
+		endRemoveColumns();
+	}
+	else
+	{
+		endRemoveRows();
+	}
+}
+
+void BaseAbstractCommonModel::notifyBeginReset()
+{
+	beginResetModel();
+}
+void BaseAbstractCommonModel::notifyEndReset()
+{
+	endResetModel();
+}
diff --git a/libraries/logic/AbstractCommonModel.h b/libraries/logic/AbstractCommonModel.h
new file mode 100644
index 00000000..31b86a23
--- /dev/null
+++ b/libraries/logic/AbstractCommonModel.h
@@ -0,0 +1,462 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QAbstractListModel>
+#include <type_traits>
+#include <functional>
+#include <memory>
+
+class BaseAbstractCommonModel : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	explicit BaseAbstractCommonModel(const Qt::Orientation orientation, QObject *parent = nullptr);
+
+	// begin QAbstractItemModel interface
+	int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+	int columnCount(const QModelIndex &parent = QModelIndex()) const override;
+	QVariant data(const QModelIndex &index, int role) const override;
+	QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+	bool setData(const QModelIndex &index, const QVariant &value, int role) override;
+	Qt::ItemFlags flags(const QModelIndex &index) const override;
+	// end QAbstractItemModel interface
+
+	virtual int size() const = 0;
+	virtual int entryCount() const = 0;
+
+	virtual QVariant formatData(const int index, int role, const QVariant &data) const { return data; }
+	virtual QVariant sanetizeData(const int index, int role, const QVariant &data) const { return data; }
+
+protected:
+	virtual QVariant get(const int index, const int entry, const int role) const = 0;
+	virtual bool set(const int index, const int entry, const int role, const QVariant &value) = 0;
+	virtual bool canSet(const int entry) const = 0;
+	virtual QString entryTitle(const int entry) const = 0;
+
+	void notifyAboutToAddObject(const int at);
+	void notifyObjectAdded();
+	void notifyAboutToRemoveObject(const int at);
+	void notifyObjectRemoved();
+	void notifyBeginReset();
+	void notifyEndReset();
+
+	const Qt::Orientation m_orientation;
+};
+
+template<typename Object>
+class AbstractCommonModel : public BaseAbstractCommonModel
+{
+public:
+	explicit AbstractCommonModel(const Qt::Orientation orientation)
+		: BaseAbstractCommonModel(orientation) {}
+	virtual ~AbstractCommonModel() {}
+
+	int size() const override { return m_objects.size(); }
+	int entryCount() const override { return m_entries.size(); }
+
+	void append(const Object &object)
+	{
+		notifyAboutToAddObject(size());
+		m_objects.append(object);
+		notifyObjectAdded();
+	}
+	void prepend(const Object &object)
+	{
+		notifyAboutToAddObject(0);
+		m_objects.prepend(object);
+		notifyObjectAdded();
+	}
+	void insert(const Object &object, const int index)
+	{
+		if (index >= size())
+		{
+			prepend(object);
+		}
+		else if (index <= 0)
+		{
+			append(object);
+		}
+		else
+		{
+			notifyAboutToAddObject(index);
+			m_objects.insert(index, object);
+			notifyObjectAdded();
+		}
+	}
+	void remove(const int index)
+	{
+		notifyAboutToRemoveObject(index);
+		m_objects.removeAt(index);
+		notifyObjectRemoved();
+	}
+	Object get(const int index) const
+	{
+		return m_objects.at(index);
+	}
+
+private:
+	friend class CommonModel;
+	QVariant get(const int index, const int entry, const int role) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return QVariant();
+		}
+		return m_entries[entry].second.value(role)->get(m_objects.at(index));
+	}
+	bool set(const int index, const int entry, const int role, const QVariant &value) override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(role);
+		if (!e->canSet())
+		{
+			return false;
+		}
+		e->set(m_objects[index], value);
+		return true;
+	}
+	bool canSet(const int entry) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(Qt::EditRole))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(Qt::EditRole);
+		return e->canSet();
+	}
+
+	QString entryTitle(const int entry) const override
+	{
+		return m_entries.at(entry).first;
+	}
+
+private:
+	struct IEntry
+	{
+		virtual ~IEntry() {}
+		virtual void set(Object &object, const QVariant &value) = 0;
+		virtual QVariant get(const Object &object) const = 0;
+		virtual bool canSet() const = 0;
+	};
+	template<typename T>
+	struct VariableEntry : public IEntry
+	{
+		typedef T (Object::*Member);
+
+		explicit VariableEntry(Member member)
+			: m_member(member) {}
+
+		void set(Object &object, const QVariant &value) override
+		{
+			object.*m_member = value.value<T>();
+		}
+		QVariant get(const Object &object) const override
+		{
+			return QVariant::fromValue<T>(object.*m_member);
+		}
+		bool canSet() const override { return true; }
+
+	private:
+		Member m_member;
+	};
+	template<typename T>
+	struct FunctionEntry : public IEntry
+	{
+		typedef T (Object::*Getter)() const;
+		typedef void (Object::*Setter)(T);
+
+		explicit FunctionEntry(Getter getter, Setter setter)
+			: m_getter(m_getter), m_setter(m_setter) {}
+
+		void set(Object &object, const QVariant &value) override
+		{
+			object.*m_setter(value.value<T>());
+		}
+		QVariant get(const Object &object) const override
+		{
+			return QVariant::fromValue<T>(object.*m_getter());
+		}
+		bool canSet() const override { return !!m_setter; }
+
+	private:
+		Getter m_getter;
+		Setter m_setter;
+	};
+
+	QList<Object> m_objects;
+	QVector<QPair<QString, QMap<int, IEntry *>>> m_entries;
+
+	void addEntryInternal(IEntry *e, const int entry, const int role)
+	{
+		if (m_entries.size() <= entry)
+		{
+			m_entries.resize(entry + 1);
+		}
+		m_entries[entry].second.insert(role, e);
+	}
+
+protected:
+	template<typename Getter, typename Setter>
+	typename std::enable_if<std::is_member_function_pointer<Getter>::value && std::is_member_function_pointer<Getter>::value, void>::type
+	addEntry(Getter getter, Setter setter, const int entry, const int role)
+	{
+		addEntryInternal(new FunctionEntry<typename std::result_of<Getter>::type>(getter, setter), entry, role);
+	}
+	template<typename Getter>
+	typename std::enable_if<std::is_member_function_pointer<Getter>::value, void>::type
+	addEntry(Getter getter, const int entry, const int role)
+	{
+		addEntryInternal(new FunctionEntry<typename std::result_of<Getter>::type>(getter, nullptr), entry, role);
+	}
+	template<typename T>
+	typename std::enable_if<!std::is_member_function_pointer<T (Object::*)>::value, void>::type
+	addEntry(T (Object::*member), const int entry, const int role)
+	{
+		addEntryInternal(new VariableEntry<T>(member), entry, role);
+	}
+
+	void setEntryTitle(const int entry, const QString &title)
+	{
+		m_entries[entry].first = title;
+	}
+};
+template<typename Object>
+class AbstractCommonModel<Object *> : public BaseAbstractCommonModel
+{
+public:
+	explicit AbstractCommonModel(const Qt::Orientation orientation)
+		: BaseAbstractCommonModel(orientation) {}
+	virtual ~AbstractCommonModel()
+	{
+		qDeleteAll(m_objects);
+	}
+
+	int size() const override { return m_objects.size(); }
+	int entryCount() const override { return m_entries.size(); }
+
+	void append(Object *object)
+	{
+		notifyAboutToAddObject(size());
+		m_objects.append(object);
+		notifyObjectAdded();
+	}
+	void prepend(Object *object)
+	{
+		notifyAboutToAddObject(0);
+		m_objects.prepend(object);
+		notifyObjectAdded();
+	}
+	void insert(Object *object, const int index)
+	{
+		if (index >= size())
+		{
+			prepend(object);
+		}
+		else if (index <= 0)
+		{
+			append(object);
+		}
+		else
+		{
+			notifyAboutToAddObject(index);
+			m_objects.insert(index, object);
+			notifyObjectAdded();
+		}
+	}
+	void remove(const int index)
+	{
+		notifyAboutToRemoveObject(index);
+		m_objects.removeAt(index);
+		notifyObjectRemoved();
+	}
+	Object *get(const int index) const
+	{
+		return m_objects.at(index);
+	}
+	int find(Object * const obj) const
+	{
+		return m_objects.indexOf(obj);
+	}
+
+	QList<Object *> getAll() const
+	{
+		return m_objects;
+	}
+
+private:
+	friend class CommonModel;
+	QVariant get(const int index, const int entry, const int role) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return QVariant();
+		}
+		return m_entries[entry].second.value(role)->get(m_objects.at(index));
+	}
+	bool set(const int index, const int entry, const int role, const QVariant &value) override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(role))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(role);
+		if (!e->canSet())
+		{
+			return false;
+		}
+		e->set(m_objects[index], value);
+		return true;
+	}
+	bool canSet(const int entry) const override
+	{
+		if (m_entries.size() < entry || !m_entries[entry].second.contains(Qt::EditRole))
+		{
+			return false;
+		}
+		IEntry *e = m_entries[entry].second.value(Qt::EditRole);
+		return e->canSet();
+	}
+
+	QString entryTitle(const int entry) const override
+	{
+		return m_entries.at(entry).first;
+	}
+
+private:
+	struct IEntry
+	{
+		virtual ~IEntry() {}
+		virtual void set(Object *object, const QVariant &value) = 0;
+		virtual QVariant get(Object *object) const = 0;
+		virtual bool canSet() const = 0;
+	};
+	template<typename T>
+	struct VariableEntry : public IEntry
+	{
+		typedef T (Object::*Member);
+
+		explicit VariableEntry(Member member)
+			: m_member(member) {}
+
+		void set(Object *object, const QVariant &value) override
+		{
+			object->*m_member = value.value<T>();
+		}
+		QVariant get(Object *object) const override
+		{
+			return QVariant::fromValue<T>(object->*m_member);
+		}
+		bool canSet() const override { return true; }
+
+	private:
+		Member m_member;
+	};
+	template<typename T>
+	struct FunctionEntry : public IEntry
+	{
+		typedef T (Object::*Getter)() const;
+		typedef void (Object::*Setter)(T);
+
+		explicit FunctionEntry(Getter getter, Setter setter)
+			: m_getter(getter), m_setter(setter) {}
+
+		void set(Object *object, const QVariant &value) override
+		{
+			(object->*m_setter)(value.value<T>());
+		}
+		QVariant get(Object *object) const override
+		{
+			return QVariant::fromValue<T>((object->*m_getter)());
+		}
+		bool canSet() const override { return !!m_setter; }
+
+	private:
+		Getter m_getter;
+		Setter m_setter;
+	};
+	template<typename T>
+	struct LambdaEntry : public IEntry
+	{
+		using Getter = std::function<T(Object *)>;
+
+		explicit LambdaEntry(Getter getter)
+			: m_getter(getter) {}
+
+		void set(Object *object, const QVariant &value) override {}
+		QVariant get(Object *object) const override
+		{
+			return QVariant::fromValue<T>(m_getter(object));
+		}
+		bool canSet() const override { return false; }
+
+	private:
+		Getter m_getter;
+	};
+
+	QList<Object *> m_objects;
+	QVector<QPair<QString, QMap<int, IEntry *>>> m_entries;
+
+	void addEntryInternal(IEntry *e, const int entry, const int role)
+	{
+		if (m_entries.size() <= entry)
+		{
+			m_entries.resize(entry + 1);
+		}
+		m_entries[entry].second.insert(role, e);
+	}
+
+protected:
+	template<typename Getter, typename Setter>
+	typename std::enable_if<std::is_member_function_pointer<Getter>::value && std::is_member_function_pointer<Getter>::value, void>::type
+	addEntry(const int entry, const int role, Getter getter, Setter setter)
+	{
+		addEntryInternal(new FunctionEntry<typename std::result_of<Getter>::type>(getter, setter), entry, role);
+	}
+	template<typename T>
+	typename std::enable_if<std::is_member_function_pointer<typename FunctionEntry<T>::Getter>::value, void>::type
+	addEntry(const int entry, const int role, typename FunctionEntry<T>::Getter getter)
+	{
+		addEntryInternal(new FunctionEntry<T>(getter, nullptr), entry, role);
+	}
+	template<typename T>
+	typename std::enable_if<!std::is_member_function_pointer<T (Object::*)>::value, void>::type
+	addEntry(const int entry, const int role, T (Object::*member))
+	{
+		addEntryInternal(new VariableEntry<T>(member), entry, role);
+	}
+	template<typename T>
+	void addEntry(const int entry, const int role, typename LambdaEntry<T>::Getter lambda)
+	{
+		addEntryInternal(new LambdaEntry<T>(lambda), entry, role);
+	}
+
+	void setEntryTitle(const int entry, const QString &title)
+	{
+		m_entries[entry].first = title;
+	}
+
+	void setAll(const QList<Object *> objects)
+	{
+		notifyBeginReset();
+		qDeleteAll(m_objects);
+		m_objects = objects;
+		notifyEndReset();
+	}
+};
diff --git a/libraries/logic/BaseConfigObject.cpp b/libraries/logic/BaseConfigObject.cpp
new file mode 100644
index 00000000..3040ac2e
--- /dev/null
+++ b/libraries/logic/BaseConfigObject.cpp
@@ -0,0 +1,103 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseConfigObject.h"
+
+#include <QTimer>
+#include <QFile>
+#include <QCoreApplication>
+#include <QDebug>
+
+#include "Exception.h"
+#include "FileSystem.h"
+
+BaseConfigObject::BaseConfigObject(const QString &filename)
+	: m_filename(filename)
+{
+	m_saveTimer = new QTimer;
+	m_saveTimer->setSingleShot(true);
+	// cppcheck-suppress pureVirtualCall
+	QObject::connect(m_saveTimer, &QTimer::timeout, [this](){saveNow();});
+	setSaveTimeout(250);
+
+	m_initialReadTimer = new QTimer;
+	m_initialReadTimer->setSingleShot(true);
+	QObject::connect(m_initialReadTimer, &QTimer::timeout, [this]()
+	{
+		loadNow();
+		m_initialReadTimer->deleteLater();
+		m_initialReadTimer = 0;
+	});
+	m_initialReadTimer->start(0);
+
+	// cppcheck-suppress pureVirtualCall
+	m_appQuitConnection = QObject::connect(qApp, &QCoreApplication::aboutToQuit, [this](){saveNow();});
+}
+BaseConfigObject::~BaseConfigObject()
+{
+	delete m_saveTimer;
+	if (m_initialReadTimer)
+	{
+		delete m_initialReadTimer;
+	}
+	QObject::disconnect(m_appQuitConnection);
+}
+
+void BaseConfigObject::setSaveTimeout(int msec)
+{
+	m_saveTimer->setInterval(msec);
+}
+
+void BaseConfigObject::scheduleSave()
+{
+	m_saveTimer->stop();
+	m_saveTimer->start();
+}
+void BaseConfigObject::saveNow()
+{
+	if (m_saveTimer->isActive())
+	{
+		m_saveTimer->stop();
+	}
+	if (m_disableSaving)
+	{
+		return;
+	}
+
+	try
+	{
+		FS::write(m_filename, doSave());
+	}
+	catch (Exception & e)
+	{
+		qCritical() << e.cause();
+	}
+}
+void BaseConfigObject::loadNow()
+{
+	if (m_saveTimer->isActive())
+	{
+		saveNow();
+	}
+
+	try
+	{
+		doLoad(FS::read(m_filename));
+	}
+	catch (Exception & e)
+	{
+		qWarning() << "Error loading" << m_filename << ":" << e.cause();
+	}
+}
diff --git a/libraries/logic/BaseConfigObject.h b/libraries/logic/BaseConfigObject.h
new file mode 100644
index 00000000..1c96b3d1
--- /dev/null
+++ b/libraries/logic/BaseConfigObject.h
@@ -0,0 +1,50 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+
+class QTimer;
+
+class BaseConfigObject
+{
+public:
+	void setSaveTimeout(int msec);
+
+protected:
+	explicit BaseConfigObject(const QString &filename);
+	virtual ~BaseConfigObject();
+
+	// cppcheck-suppress pureVirtualCall
+	virtual QByteArray doSave() const = 0;
+	virtual void doLoad(const QByteArray &data) = 0;
+
+	void setSavingDisabled(bool savingDisabled) { m_disableSaving = savingDisabled; }
+
+	QString fileName() const { return m_filename; }
+
+public:
+	void scheduleSave();
+	void saveNow();
+	void loadNow();
+
+private:
+	QTimer *m_saveTimer;
+	QTimer *m_initialReadTimer;
+	QString m_filename;
+	QMetaObject::Connection m_appQuitConnection;
+	bool m_disableSaving = false;
+};
diff --git a/libraries/logic/BaseInstaller.cpp b/libraries/logic/BaseInstaller.cpp
new file mode 100644
index 00000000..cb762ebd
--- /dev/null
+++ b/libraries/logic/BaseInstaller.cpp
@@ -0,0 +1,61 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QFile>
+
+#include "BaseInstaller.h"
+#include "minecraft/onesix/OneSixInstance.h"
+
+BaseInstaller::BaseInstaller()
+{
+
+}
+
+bool BaseInstaller::isApplied(OneSixInstance *on)
+{
+	return QFile::exists(filename(on->instanceRoot()));
+}
+
+bool BaseInstaller::add(OneSixInstance *to)
+{
+	if (!patchesDir(to->instanceRoot()).exists())
+	{
+		QDir(to->instanceRoot()).mkdir("patches");
+	}
+
+	if (isApplied(to))
+	{
+		if (!remove(to))
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+
+bool BaseInstaller::remove(OneSixInstance *from)
+{
+	return QFile::remove(filename(from->instanceRoot()));
+}
+
+QString BaseInstaller::filename(const QString &root) const
+{
+	return patchesDir(root).absoluteFilePath(id() + ".json");
+}
+QDir BaseInstaller::patchesDir(const QString &root) const
+{
+	return QDir(root + "/patches/");
+}
diff --git a/libraries/logic/BaseInstaller.h b/libraries/logic/BaseInstaller.h
new file mode 100644
index 00000000..a50c8cb1
--- /dev/null
+++ b/libraries/logic/BaseInstaller.h
@@ -0,0 +1,46 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class OneSixInstance;
+class QDir;
+class QString;
+class QObject;
+class Task;
+class BaseVersion;
+typedef std::shared_ptr<BaseVersion> BaseVersionPtr;
+
+class MULTIMC_LOGIC_EXPORT BaseInstaller
+{
+public:
+	BaseInstaller();
+	virtual ~BaseInstaller(){};
+	bool isApplied(OneSixInstance *on);
+
+	virtual bool add(OneSixInstance *to);
+	virtual bool remove(OneSixInstance *from);
+
+	virtual Task *createInstallTask(OneSixInstance *instance, BaseVersionPtr version, QObject *parent) = 0;
+
+protected:
+	virtual QString id() const = 0;
+	QString filename(const QString &root) const;
+	QDir patchesDir(const QString &root) const;
+};
diff --git a/libraries/logic/BaseInstance.cpp b/libraries/logic/BaseInstance.cpp
new file mode 100644
index 00000000..ce55d5e4
--- /dev/null
+++ b/libraries/logic/BaseInstance.cpp
@@ -0,0 +1,270 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseInstance.h"
+
+#include <QFileInfo>
+#include <QDir>
+
+#include "settings/INISettingsObject.h"
+#include "settings/Setting.h"
+#include "settings/OverrideSetting.h"
+
+#include "minecraft/MinecraftVersionList.h"
+#include "FileSystem.h"
+#include "Commandline.h"
+
+BaseInstance::BaseInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir)
+	: QObject()
+{
+	m_settings = settings;
+	m_rootDir = rootDir;
+
+	m_settings->registerSetting("name", "Unnamed Instance");
+	m_settings->registerSetting("iconKey", "default");
+	m_settings->registerSetting("notes", "");
+	m_settings->registerSetting("lastLaunchTime", 0);
+	m_settings->registerSetting("totalTimePlayed", 0);
+
+	// Custom Commands
+	auto commandSetting = m_settings->registerSetting({"OverrideCommands","OverrideLaunchCmd"}, false);
+	m_settings->registerOverride(globalSettings->getSetting("PreLaunchCommand"), commandSetting);
+	m_settings->registerOverride(globalSettings->getSetting("WrapperCommand"), commandSetting);
+	m_settings->registerOverride(globalSettings->getSetting("PostExitCommand"), commandSetting);
+
+	// Console
+	auto consoleSetting = m_settings->registerSetting("OverrideConsole", false);
+	m_settings->registerOverride(globalSettings->getSetting("ShowConsole"), consoleSetting);
+	m_settings->registerOverride(globalSettings->getSetting("AutoCloseConsole"), consoleSetting);
+	m_settings->registerOverride(globalSettings->getSetting("LogPrePostOutput"), consoleSetting);
+}
+
+QString BaseInstance::getPreLaunchCommand()
+{
+	return settings()->get("PreLaunchCommand").toString();
+}
+
+QString BaseInstance::getWrapperCommand()
+{
+	return settings()->get("WrapperCommand").toString();
+}
+
+QString BaseInstance::getPostExitCommand()
+{
+	return settings()->get("PostExitCommand").toString();
+}
+
+void BaseInstance::iconUpdated(QString key)
+{
+	if(iconKey() == key)
+	{
+		emit propertiesChanged(this);
+	}
+}
+
+void BaseInstance::nuke()
+{
+	FS::deletePath(instanceRoot());
+	emit nuked(this);
+}
+
+QString BaseInstance::id() const
+{
+	return QFileInfo(instanceRoot()).fileName();
+}
+
+bool BaseInstance::isRunning() const
+{
+	return m_isRunning;
+}
+
+void BaseInstance::setRunning(bool running)
+{
+	if(running && !m_isRunning)
+	{
+		m_timeStarted = QDateTime::currentDateTime();
+	}
+	else if(!running && m_isRunning)
+	{
+		qint64 current = settings()->get("totalTimePlayed").toLongLong();
+		QDateTime timeEnded = QDateTime::currentDateTime();
+		settings()->set("totalTimePlayed", current + m_timeStarted.secsTo(timeEnded));
+		emit propertiesChanged(this);
+	}
+	m_isRunning = running;
+}
+
+int64_t BaseInstance::totalTimePlayed() const
+{
+	qint64 current = settings()->get("totalTimePlayed").toLongLong();
+	if(m_isRunning)
+	{
+		QDateTime timeNow = QDateTime::currentDateTime();
+		return current + m_timeStarted.secsTo(timeNow);
+	}
+	return current;
+}
+
+void BaseInstance::resetTimePlayed()
+{
+	settings()->reset("totalTimePlayed");
+}
+
+QString BaseInstance::instanceType() const
+{
+	return m_settings->get("InstanceType").toString();
+}
+
+QString BaseInstance::instanceRoot() const
+{
+	return m_rootDir;
+}
+
+InstancePtr BaseInstance::getSharedPtr()
+{
+	return shared_from_this();
+}
+
+SettingsObjectPtr BaseInstance::settings() const
+{
+	return m_settings;
+}
+
+BaseInstance::InstanceFlags BaseInstance::flags() const
+{
+	return m_flags;
+}
+
+void BaseInstance::setFlags(const InstanceFlags &flags)
+{
+	if (flags != m_flags)
+	{
+		m_flags = flags;
+		emit flagsChanged();
+		emit propertiesChanged(this);
+	}
+}
+
+void BaseInstance::setFlag(const BaseInstance::InstanceFlag flag)
+{
+	// nothing to set?
+	if(flag & m_flags)
+		return;
+	m_flags |= flag;
+	emit flagsChanged();
+	emit propertiesChanged(this);
+}
+
+void BaseInstance::unsetFlag(const BaseInstance::InstanceFlag flag)
+{
+	// nothing to unset?
+	if(!(flag & m_flags))
+		return;
+	m_flags &= ~flag;
+	emit flagsChanged();
+	emit propertiesChanged(this);
+}
+
+bool BaseInstance::canLaunch() const
+{
+	return !(flags() & VersionBrokenFlag);
+}
+
+bool BaseInstance::reload()
+{
+	return m_settings->reload();
+}
+
+qint64 BaseInstance::lastLaunch() const
+{
+	return m_settings->get("lastLaunchTime").value<qint64>();
+}
+
+void BaseInstance::setLastLaunch(qint64 val)
+{
+	//FIXME: if no change, do not set. setting involves saving a file.
+	m_settings->set("lastLaunchTime", val);
+	emit propertiesChanged(this);
+}
+
+void BaseInstance::setGroupInitial(QString val)
+{
+	if(m_group == val)
+	{
+		return;
+	}
+	m_group = val;
+	emit propertiesChanged(this);
+}
+
+void BaseInstance::setGroupPost(QString val)
+{
+	if(m_group == val)
+	{
+		return;
+	}
+	setGroupInitial(val);
+	emit groupChanged();
+}
+
+QString BaseInstance::group() const
+{
+	return m_group;
+}
+
+void BaseInstance::setNotes(QString val)
+{
+	//FIXME: if no change, do not set. setting involves saving a file.
+	m_settings->set("notes", val);
+}
+
+QString BaseInstance::notes() const
+{
+	return m_settings->get("notes").toString();
+}
+
+void BaseInstance::setIconKey(QString val)
+{
+	//FIXME: if no change, do not set. setting involves saving a file.
+	m_settings->set("iconKey", val);
+	emit propertiesChanged(this);
+}
+
+QString BaseInstance::iconKey() const
+{
+	return m_settings->get("iconKey").toString();
+}
+
+void BaseInstance::setName(QString val)
+{
+	//FIXME: if no change, do not set. setting involves saving a file.
+	m_settings->set("name", val);
+	emit propertiesChanged(this);
+}
+
+QString BaseInstance::name() const
+{
+	return m_settings->get("name").toString();
+}
+
+QString BaseInstance::windowTitle() const
+{
+	return "MultiMC: " + name();
+}
+
+QStringList BaseInstance::extraArguments() const
+{
+	return Commandline::splitArgs(settings()->get("JvmArgs").toString());
+}
diff --git a/libraries/logic/BaseInstance.h b/libraries/logic/BaseInstance.h
new file mode 100644
index 00000000..5e587c48
--- /dev/null
+++ b/libraries/logic/BaseInstance.h
@@ -0,0 +1,243 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QDateTime>
+#include <QSet>
+#include <QProcess>
+
+#include "settings/SettingsObject.h"
+
+#include "settings/INIFile.h"
+#include "BaseVersionList.h"
+#include "minecraft/auth/MojangAccount.h"
+#include "launch/MessageLevel.h"
+#include "pathmatcher/IPathMatcher.h"
+
+#include "multimc_logic_export.h"
+
+class QDir;
+class Task;
+class LaunchTask;
+class BaseInstance;
+
+// pointer for lazy people
+typedef std::shared_ptr<BaseInstance> InstancePtr;
+
+/*!
+ * \brief Base class for instances.
+ * This class implements many functions that are common between instances and
+ * provides a standard interface for all instances.
+ *
+ * To create a new instance type, create a new class inheriting from this class
+ * and implement the pure virtual functions.
+ */
+class MULTIMC_LOGIC_EXPORT BaseInstance : public QObject, public std::enable_shared_from_this<BaseInstance>
+{
+	Q_OBJECT
+protected:
+	/// no-touchy!
+	BaseInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+
+public:
+	/// virtual destructor to make sure the destruction is COMPLETE
+	virtual ~BaseInstance() {};
+
+	virtual void copy(const QDir &newDir) {}
+
+	virtual void init() = 0;
+
+	/// nuke thoroughly - deletes the instance contents, notifies the list/model which is
+	/// responsible of cleaning up the husk
+	void nuke();
+
+	/// The instance's ID. The ID SHALL be determined by MMC internally. The ID IS guaranteed to
+	/// be unique.
+	virtual QString id() const;
+
+	void setRunning(bool running);
+	bool isRunning() const;
+	int64_t totalTimePlayed() const;
+	void resetTimePlayed();
+
+	/// get the type of this instance
+	QString instanceType() const;
+
+	/// Path to the instance's root directory.
+	QString instanceRoot() const;
+
+	QString name() const;
+	void setName(QString val);
+
+	/// Value used for instance window titles
+	QString windowTitle() const;
+
+	QString iconKey() const;
+	void setIconKey(QString val);
+
+	QString notes() const;
+	void setNotes(QString val);
+
+	QString group() const;
+	void setGroupInitial(QString val);
+	void setGroupPost(QString val);
+
+	QString getPreLaunchCommand();
+	QString getPostExitCommand();
+	QString getWrapperCommand();
+
+	/// guess log level from a line of game log
+	virtual MessageLevel::Enum guessLevel(const QString &line, MessageLevel::Enum level)
+	{
+		return level;
+	};
+
+	virtual QStringList extraArguments() const;
+
+	virtual QString intendedVersionId() const = 0;
+	virtual bool setIntendedVersionId(QString version) = 0;
+
+	/*!
+	 * The instance's current version.
+	 * This value represents the instance's current version. If this value is
+	 * different from the intendedVersion, the instance should be updated.
+	 * \warning Don't change this value unless you know what you're doing.
+	 */
+	virtual QString currentVersionId() const = 0;
+
+	/*!
+	 * Whether or not 'the game' should be downloaded when the instance is launched.
+	 */
+	virtual bool shouldUpdate() const = 0;
+	virtual void setShouldUpdate(bool val) = 0;
+
+	/// Traits. Normally inside the version, depends on instance implementation.
+	virtual QSet <QString> traits() = 0;
+
+	/**
+	 * Gets the time that the instance was last launched.
+	 * Stored in milliseconds since epoch.
+	 */
+	qint64 lastLaunch() const;
+	/// Sets the last launched time to 'val' milliseconds since epoch
+	void setLastLaunch(qint64 val = QDateTime::currentMSecsSinceEpoch());
+
+	InstancePtr getSharedPtr();
+
+	/*!
+	 * \brief Gets a pointer to this instance's version list.
+	 * \return A pointer to the available version list for this instance.
+	 */
+	virtual std::shared_ptr<BaseVersionList> versionList() const = 0;
+
+	/*!
+	 * \brief Gets this instance's settings object.
+	 * This settings object stores instance-specific settings.
+	 * \return A pointer to this instance's settings object.
+	 */
+	virtual SettingsObjectPtr settings() const;
+
+	/// returns a valid update task
+	virtual std::shared_ptr<Task> createUpdateTask() = 0;
+
+	/// returns a valid launcher (task container)
+	virtual std::shared_ptr<LaunchTask> createLaunchTask(AuthSessionPtr account) = 0;
+
+	/*!
+	 * Returns a task that should be done right before launch
+	 * This task should do any extra preparations needed
+	 */
+	virtual std::shared_ptr<Task> createJarModdingTask() = 0;
+
+	/*!
+	 * Create envrironment variables for running the instance
+	 */
+	virtual QProcessEnvironment createEnvironment() = 0;
+
+	/*!
+	 * Returns a matcher that can maps relative paths within the instance to whether they are 'log files'
+	 */
+	virtual IPathMatcher::Ptr getLogFileMatcher() = 0;
+
+	/*!
+	 * Returns the root folder to use for looking up log files
+	 */
+	virtual QString getLogFileRoot() = 0;
+
+	/*!
+	 * does any necessary cleanups after the instance finishes. also runs before\
+	 * TODO: turn into a task that can run asynchronously
+	 */
+	virtual void cleanupAfterRun() = 0;
+
+	virtual QString getStatusbarDescription() = 0;
+
+	/// FIXME: this really should be elsewhere...
+	virtual QString instanceConfigFolder() const = 0;
+
+	/// get variables this instance exports
+	virtual QMap<QString, QString> getVariables() const = 0;
+
+	virtual QString typeName() const = 0;
+
+	enum InstanceFlag
+	{
+		VersionBrokenFlag = 0x01,
+		UpdateAvailable = 0x02
+	};
+	Q_DECLARE_FLAGS(InstanceFlags, InstanceFlag)
+	InstanceFlags flags() const;
+	void setFlags(const InstanceFlags &flags);
+	void setFlag(const InstanceFlag flag);
+	void unsetFlag(const InstanceFlag flag);
+
+	bool canLaunch() const;
+	virtual bool canExport() const = 0;
+
+	virtual bool reload();
+
+signals:
+	/*!
+	 * \brief Signal emitted when properties relevant to the instance view change
+	 */
+	void propertiesChanged(BaseInstance *inst);
+	/*!
+	 * \brief Signal emitted when groups are affected in any way
+	 */
+	void groupChanged();
+	/*!
+	 * \brief The instance just got nuked. Hurray!
+	 */
+	void nuked(BaseInstance *inst);
+
+	void flagsChanged();
+
+protected slots:
+	void iconUpdated(QString key);
+
+protected:
+	QString m_rootDir;
+	QString m_group;
+	SettingsObjectPtr m_settings;
+	InstanceFlags m_flags;
+	bool m_isRunning = false;
+	QDateTime m_timeStarted;
+};
+
+Q_DECLARE_METATYPE(std::shared_ptr<BaseInstance>)
+Q_DECLARE_METATYPE(BaseInstance::InstanceFlag)
+Q_DECLARE_OPERATORS_FOR_FLAGS(BaseInstance::InstanceFlags)
diff --git a/libraries/logic/BaseVersion.h b/libraries/logic/BaseVersion.h
new file mode 100644
index 00000000..80767518
--- /dev/null
+++ b/libraries/logic/BaseVersion.h
@@ -0,0 +1,59 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+#include <QString>
+#include <QMetaType>
+
+/*!
+ * An abstract base class for versions.
+ */
+class BaseVersion
+{
+public:
+	virtual ~BaseVersion() {}
+	/*!
+	 * A string used to identify this version in config files.
+	 * This should be unique within the version list or shenanigans will occur.
+	 */
+	virtual QString descriptor() = 0;
+
+	/*!
+	 * The name of this version as it is displayed to the user.
+	 * For example: "1.5.1"
+	 */
+	virtual QString name() = 0;
+
+	/*!
+	 * This should return a string that describes
+	 * the kind of version this is (Stable, Beta, Snapshot, whatever)
+	 */
+	virtual QString typeString() const = 0;
+
+	virtual bool operator<(BaseVersion &a)
+	{
+		return name() < a.name();
+	};
+	virtual bool operator>(BaseVersion &a)
+	{
+		return name() > a.name();
+	};
+};
+
+typedef std::shared_ptr<BaseVersion> BaseVersionPtr;
+
+Q_DECLARE_METATYPE(BaseVersionPtr)
diff --git a/libraries/logic/BaseVersionList.cpp b/libraries/logic/BaseVersionList.cpp
new file mode 100644
index 00000000..b34f318c
--- /dev/null
+++ b/libraries/logic/BaseVersionList.cpp
@@ -0,0 +1,104 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseVersionList.h"
+#include "BaseVersion.h"
+
+BaseVersionList::BaseVersionList(QObject *parent) : QAbstractListModel(parent)
+{
+}
+
+BaseVersionPtr BaseVersionList::findVersion(const QString &descriptor)
+{
+	for (int i = 0; i < count(); i++)
+	{
+		if (at(i)->descriptor() == descriptor)
+			return at(i);
+	}
+	return BaseVersionPtr();
+}
+
+BaseVersionPtr BaseVersionList::getLatestStable() const
+{
+	if (count() <= 0)
+		return BaseVersionPtr();
+	else
+		return at(0);
+}
+
+BaseVersionPtr BaseVersionList::getRecommended() const
+{
+	return getLatestStable();
+}
+
+QVariant BaseVersionList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	BaseVersionPtr version = at(index.row());
+
+	switch (role)
+	{
+	case VersionPointerRole:
+		return qVariantFromValue(version);
+
+	case VersionRole:
+		return version->name();
+
+	case VersionIdRole:
+		return version->descriptor();
+
+	case TypeRole:
+		return version->typeString();
+
+	default:
+		return QVariant();
+	}
+}
+
+BaseVersionList::RoleList BaseVersionList::providesRoles() const
+{
+	return {VersionPointerRole, VersionRole, VersionIdRole, TypeRole};
+}
+
+int BaseVersionList::rowCount(const QModelIndex &parent) const
+{
+	// Return count
+	return count();
+}
+
+int BaseVersionList::columnCount(const QModelIndex &parent) const
+{
+	return 1;
+}
+
+QHash<int, QByteArray> BaseVersionList::roleNames() const
+{
+	QHash<int, QByteArray> roles = QAbstractListModel::roleNames();
+	roles.insert(VersionRole, "version");
+	roles.insert(VersionIdRole, "versionId");
+	roles.insert(ParentGameVersionRole, "parentGameVersion");
+	roles.insert(RecommendedRole, "recommended");
+	roles.insert(LatestRole, "latest");
+	roles.insert(TypeRole, "type");
+	roles.insert(BranchRole, "branch");
+	roles.insert(PathRole, "path");
+	roles.insert(ArchitectureRole, "architecture");
+	return roles;
+}
diff --git a/libraries/logic/BaseVersionList.h b/libraries/logic/BaseVersionList.h
new file mode 100644
index 00000000..73d2ee1f
--- /dev/null
+++ b/libraries/logic/BaseVersionList.h
@@ -0,0 +1,126 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QVariant>
+#include <QAbstractListModel>
+
+#include "BaseVersion.h"
+#include "tasks/Task.h"
+#include "multimc_logic_export.h"
+
+/*!
+ * \brief Class that each instance type's version list derives from.
+ * Version lists are the lists that keep track of the available game versions
+ * for that instance. This list will not be loaded on startup. It will be loaded
+ * when the list's load function is called. Before using the version list, you
+ * should check to see if it has been loaded yet and if not, load the list.
+ *
+ * Note that this class also inherits from QAbstractListModel. Methods from that
+ * class determine how this version list shows up in a list view. Said methods
+ * all have a default implementation, but they can be overridden by plugins to
+ * change the behavior of the list.
+ */
+class MULTIMC_LOGIC_EXPORT BaseVersionList : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	enum ModelRoles
+	{
+		VersionPointerRole = Qt::UserRole,
+		VersionRole,
+		VersionIdRole,
+		ParentGameVersionRole,
+		RecommendedRole,
+		LatestRole,
+		TypeRole,
+		BranchRole,
+		PathRole,
+		ArchitectureRole,
+		SortRole
+	};
+	typedef QList<int> RoleList;
+
+	explicit BaseVersionList(QObject *parent = 0);
+
+	/*!
+	 * \brief Gets a task that will reload the version list.
+	 * Simply execute the task to load the list.
+	 * The task returned by this function should reset the model when it's done.
+	 * \return A pointer to a task that reloads the version list.
+	 */
+	virtual Task *getLoadTask() = 0;
+
+	//! Checks whether or not the list is loaded. If this returns false, the list should be
+	//loaded.
+	virtual bool isLoaded() = 0;
+
+	//! Gets the version at the given index.
+	virtual const BaseVersionPtr at(int i) const = 0;
+
+	//! Returns the number of versions in the list.
+	virtual int count() const = 0;
+
+	//////// List Model Functions ////////
+	virtual QVariant data(const QModelIndex &index, int role) const;
+	virtual int rowCount(const QModelIndex &parent) const;
+	virtual int columnCount(const QModelIndex &parent) const;
+	virtual QHash<int, QByteArray> roleNames() const override;
+
+	//! which roles are provided by this version list?
+	virtual RoleList providesRoles() const;
+
+	/*!
+	 * \brief Finds a version by its descriptor.
+	 * \param The descriptor of the version to find.
+	 * \return A const pointer to the version with the given descriptor. NULL if
+	 * one doesn't exist.
+	 */
+	virtual BaseVersionPtr findVersion(const QString &descriptor);
+
+	/*!
+	 * \brief Gets the latest stable version from this list
+	 */
+	virtual BaseVersionPtr getLatestStable() const;
+
+	/*!
+	 * \brief Gets the recommended version from this list
+	 * If the list doesn't support recommended versions, this works exactly as getLatestStable
+	 */
+	virtual BaseVersionPtr getRecommended() const;
+
+	/*!
+	 * Sorts the version list.
+	 */
+	virtual void sortVersions() = 0;
+
+protected
+slots:
+	/*!
+	 * Updates this list with the given list of versions.
+	 * This is done by copying each version in the given list and inserting it
+	 * into this one.
+	 * We need to do this so that we can set the parents of the versions are set to this
+	 * version list. This can't be done in the load task, because the versions the load
+	 * task creates are on the load task's thread and Qt won't allow their parents
+	 * to be set to something created on another thread.
+	 * To get around that problem, we invoke this method on the GUI thread, which
+	 * then copies the versions and sets their parents correctly.
+	 * \param versions List of versions whose parents should be set.
+	 */
+	virtual void updateListData(QList<BaseVersionPtr> versions) = 0;
+};
diff --git a/libraries/logic/CMakeLists.txt b/libraries/logic/CMakeLists.txt
new file mode 100644
index 00000000..317627d5
--- /dev/null
+++ b/libraries/logic/CMakeLists.txt
@@ -0,0 +1,344 @@
+project(MultiMC_logic)
+
+set(LOGIC_SOURCES
+	# LOGIC - Base classes and infrastructure
+	BaseInstaller.h
+	BaseInstaller.cpp
+	BaseVersionList.h
+	BaseVersionList.cpp
+	InstanceList.h
+	InstanceList.cpp
+	BaseVersion.h
+	BaseInstance.h
+	BaseInstance.cpp
+	NullInstance.h
+	MMCZip.h
+	MMCZip.cpp
+	MMCStrings.h
+	MMCStrings.cpp
+	BaseConfigObject.h
+	BaseConfigObject.cpp
+	AbstractCommonModel.h
+	AbstractCommonModel.cpp
+	TypeMagic.h
+
+	# Prefix tree where node names are strings between separators
+	SeparatorPrefixTree.h
+
+	# WARNING: globals live here
+	Env.h
+	Env.cpp
+
+	# JSON parsing helpers
+	Json.h
+	Json.cpp
+
+	FileSystem.h
+	FileSystem.cpp
+
+	Exception.h
+
+	# RW lock protected map
+	RWStorage.h
+
+	# A variable that has an implicit default value and keeps track of changes
+	DefaultVariable.h
+
+	# a smart pointer wrapper intended for safer use with Qt signal/slot mechanisms
+	QObjectPtr.h
+
+	# Resources
+	resources/Resource.cpp
+	resources/Resource.h
+	resources/ResourceHandler.cpp
+	resources/ResourceHandler.h
+	resources/ResourceObserver.cpp
+	resources/ResourceObserver.h
+	resources/ResourceProxyModel.h
+	resources/ResourceProxyModel.cpp
+
+	# Path matchers
+	pathmatcher/FSTreeMatcher.h
+	pathmatcher/IPathMatcher.h
+	pathmatcher/MultiMatcher.h
+	pathmatcher/RegexpMatcher.h
+
+	# Compression support
+	GZip.h
+	GZip.cpp
+
+	# Command line parameter parsing
+	Commandline.h
+	Commandline.cpp
+
+	# Version number string support
+	Version.h
+	Version.cpp
+
+	# network stuffs
+	net/NetAction.h
+	net/MD5EtagDownload.h
+	net/MD5EtagDownload.cpp
+	net/ByteArrayDownload.h
+	net/ByteArrayDownload.cpp
+	net/CacheDownload.h
+	net/CacheDownload.cpp
+	net/NetJob.h
+	net/NetJob.cpp
+	net/HttpMetaCache.h
+	net/HttpMetaCache.cpp
+	net/PasteUpload.h
+	net/PasteUpload.cpp
+	net/URLConstants.h
+	net/URLConstants.cpp
+
+	# Yggdrasil login stuff
+	minecraft/auth/AuthSession.h
+	minecraft/auth/AuthSession.cpp
+	minecraft/auth/MojangAccountList.h
+	minecraft/auth/MojangAccountList.cpp
+	minecraft/auth/MojangAccount.h
+	minecraft/auth/MojangAccount.cpp
+	minecraft/auth/YggdrasilTask.h
+	minecraft/auth/YggdrasilTask.cpp
+	minecraft/auth/flows/AuthenticateTask.h
+	minecraft/auth/flows/AuthenticateTask.cpp
+	minecraft/auth/flows/RefreshTask.cpp
+	minecraft/auth/flows/RefreshTask.cpp
+	minecraft/auth/flows/ValidateTask.h
+	minecraft/auth/flows/ValidateTask.cpp
+
+	# Game launch logic
+	launch/steps/CheckJava.cpp
+	launch/steps/CheckJava.h
+	launch/steps/LaunchMinecraft.cpp
+	launch/steps/LaunchMinecraft.h
+	launch/steps/ModMinecraftJar.cpp
+	launch/steps/ModMinecraftJar.h
+	launch/steps/PostLaunchCommand.cpp
+	launch/steps/PostLaunchCommand.h
+	launch/steps/PreLaunchCommand.cpp
+	launch/steps/PreLaunchCommand.h
+	launch/steps/TextPrint.cpp
+	launch/steps/TextPrint.h
+	launch/steps/Update.cpp
+	launch/steps/Update.h
+	launch/LaunchStep.cpp
+	launch/LaunchStep.h
+	launch/LaunchTask.cpp
+	launch/LaunchTask.h
+	launch/LoggedProcess.cpp
+	launch/LoggedProcess.h
+	launch/MessageLevel.cpp
+	launch/MessageLevel.h
+
+	# Update system
+	updater/GoUpdate.h
+	updater/GoUpdate.cpp
+	updater/UpdateChecker.h
+	updater/UpdateChecker.cpp
+	updater/DownloadTask.h
+	updater/DownloadTask.cpp
+
+	# Notifications - short warning messages
+	notifications/NotificationChecker.h
+	notifications/NotificationChecker.cpp
+
+	# News System
+	news/NewsChecker.h
+	news/NewsChecker.cpp
+	news/NewsEntry.h
+	news/NewsEntry.cpp
+
+	# Status system
+	status/StatusChecker.h
+	status/StatusChecker.cpp
+
+	# Minecraft support
+	minecraft/onesix/OneSixUpdate.h
+	minecraft/onesix/OneSixUpdate.cpp
+	minecraft/onesix/OneSixInstance.h
+	minecraft/onesix/OneSixInstance.cpp
+	minecraft/onesix/OneSixProfileStrategy.cpp
+	minecraft/onesix/OneSixProfileStrategy.h
+	minecraft/onesix/OneSixVersionFormat.cpp
+	minecraft/onesix/OneSixVersionFormat.h
+	minecraft/legacy/LegacyUpdate.h
+	minecraft/legacy/LegacyUpdate.cpp
+	minecraft/legacy/LegacyInstance.h
+	minecraft/legacy/LegacyInstance.cpp
+	minecraft/legacy/LwjglVersionList.h
+	minecraft/legacy/LwjglVersionList.cpp
+	minecraft/GradleSpecifier.h
+	minecraft/MinecraftProfile.cpp
+	minecraft/MinecraftProfile.h
+	minecraft/MojangVersionFormat.cpp
+	minecraft/MojangVersionFormat.h
+	minecraft/JarMod.h
+	minecraft/MinecraftInstance.cpp
+	minecraft/MinecraftInstance.h
+	minecraft/MinecraftVersion.cpp
+	minecraft/MinecraftVersion.h
+	minecraft/MinecraftVersionList.cpp
+	minecraft/MinecraftVersionList.h
+	minecraft/Rule.cpp
+	minecraft/Rule.h
+	minecraft/OpSys.cpp
+	minecraft/OpSys.h
+	minecraft/ParseUtils.cpp
+	minecraft/ParseUtils.h
+	minecraft/ProfileUtils.cpp
+	minecraft/ProfileUtils.h
+	minecraft/ProfileStrategy.h
+	minecraft/Library.cpp
+	minecraft/Library.h
+	minecraft/MojangDownloadInfo.h
+	minecraft/VersionBuildError.h
+	minecraft/VersionFile.cpp
+	minecraft/VersionFile.h
+	minecraft/ProfilePatch.h
+	minecraft/VersionFilterData.h
+	minecraft/VersionFilterData.cpp
+	minecraft/Mod.h
+	minecraft/Mod.cpp
+	minecraft/ModList.h
+	minecraft/ModList.cpp
+	minecraft/World.h
+	minecraft/World.cpp
+	minecraft/WorldList.h
+	minecraft/WorldList.cpp
+
+	# FTB
+	minecraft/ftb/OneSixFTBInstance.h
+	minecraft/ftb/OneSixFTBInstance.cpp
+	minecraft/ftb/LegacyFTBInstance.h
+	minecraft/ftb/LegacyFTBInstance.cpp
+	minecraft/ftb/FTBProfileStrategy.h
+	minecraft/ftb/FTBProfileStrategy.cpp
+	minecraft/ftb/FTBPlugin.h
+	minecraft/ftb/FTBPlugin.cpp
+
+	# A Recursive file system watcher
+	RecursiveFileSystemWatcher.h
+	RecursiveFileSystemWatcher.cpp
+
+	# the screenshots feature
+	screenshots/Screenshot.h
+	screenshots/ImgurUpload.h
+	screenshots/ImgurUpload.cpp
+	screenshots/ImgurAlbumCreation.h
+	screenshots/ImgurAlbumCreation.cpp
+
+	# Tasks
+	tasks/Task.h
+	tasks/Task.cpp
+	tasks/ThreadTask.h
+	tasks/ThreadTask.cpp
+	tasks/SequentialTask.h
+	tasks/SequentialTask.cpp
+
+	# Settings
+	settings/INIFile.cpp
+	settings/INIFile.h
+	settings/INISettingsObject.cpp
+	settings/INISettingsObject.h
+	settings/OverrideSetting.cpp
+	settings/OverrideSetting.h
+	settings/PassthroughSetting.cpp
+	settings/PassthroughSetting.h
+	settings/Setting.cpp
+	settings/Setting.h
+	settings/SettingsObject.cpp
+	settings/SettingsObject.h
+
+	# Java related code
+	java/JavaChecker.h
+	java/JavaChecker.cpp
+	java/JavaCheckerJob.h
+	java/JavaCheckerJob.cpp
+	java/JavaInstall.h
+	java/JavaInstall.cpp
+	java/JavaInstallList.h
+	java/JavaInstallList.cpp
+	java/JavaUtils.h
+	java/JavaUtils.cpp
+	java/JavaVersion.h
+	java/JavaVersion.cpp
+
+	# Assets
+	minecraft/AssetsUtils.h
+	minecraft/AssetsUtils.cpp
+
+	# Forge and all things forge related
+	minecraft/forge/ForgeVersion.h
+	minecraft/forge/ForgeVersion.cpp
+	minecraft/forge/ForgeVersionList.h
+	minecraft/forge/ForgeVersionList.cpp
+	minecraft/forge/ForgeXzDownload.h
+	minecraft/forge/ForgeXzDownload.cpp
+	minecraft/forge/LegacyForge.h
+	minecraft/forge/LegacyForge.cpp
+	minecraft/forge/ForgeInstaller.h
+	minecraft/forge/ForgeInstaller.cpp
+
+	# Liteloader and related things
+	minecraft/liteloader/LiteLoaderInstaller.h
+	minecraft/liteloader/LiteLoaderInstaller.cpp
+	minecraft/liteloader/LiteLoaderVersionList.h
+	minecraft/liteloader/LiteLoaderVersionList.cpp
+
+	# Translations
+	trans/TranslationDownloader.h
+	trans/TranslationDownloader.cpp
+
+	# Tools
+	tools/BaseExternalTool.cpp
+	tools/BaseExternalTool.h
+	tools/BaseProfiler.cpp
+	tools/BaseProfiler.h
+	tools/JProfiler.cpp
+	tools/JProfiler.h
+	tools/JVisualVM.cpp
+	tools/JVisualVM.h
+	tools/MCEditTool.cpp
+	tools/MCEditTool.h
+
+	# Wonko
+	wonko/tasks/BaseWonkoEntityRemoteLoadTask.cpp
+	wonko/tasks/BaseWonkoEntityRemoteLoadTask.h
+	wonko/tasks/BaseWonkoEntityLocalLoadTask.cpp
+	wonko/tasks/BaseWonkoEntityLocalLoadTask.h
+	wonko/format/WonkoFormatV1.cpp
+	wonko/format/WonkoFormatV1.h
+	wonko/format/WonkoFormat.cpp
+	wonko/format/WonkoFormat.h
+	wonko/BaseWonkoEntity.cpp
+	wonko/BaseWonkoEntity.h
+	wonko/WonkoVersionList.cpp
+	wonko/WonkoVersionList.h
+	wonko/WonkoVersion.cpp
+	wonko/WonkoVersion.h
+	wonko/WonkoIndex.cpp
+	wonko/WonkoIndex.h
+	wonko/WonkoUtil.cpp
+	wonko/WonkoUtil.h
+	wonko/WonkoReference.cpp
+	wonko/WonkoReference.h
+)
+################################ COMPILE ################################
+
+# we need zlib
+find_package(ZLIB REQUIRED)
+
+add_library(MultiMC_logic SHARED ${LOGIC_SOURCES})
+set_target_properties(MultiMC_logic PROPERTIES CXX_VISIBILITY_PRESET hidden VISIBILITY_INLINES_HIDDEN 1)
+
+generate_export_header(MultiMC_logic)
+
+# Link
+target_link_libraries(MultiMC_logic xz-embedded unpack200 ${QUAZIP_LIBRARIES} nbt++ ${ZLIB_LIBRARIES})
+qt5_use_modules(MultiMC_logic Core Xml Network Concurrent)
+add_dependencies(MultiMC_logic QuaZIP)
+
+# Mark and export headers
+target_include_directories(MultiMC_logic PUBLIC "${CMAKE_CURRENT_BINARY_DIR}" "${CMAKE_CURRENT_SOURCE_DIR}" PRIVATE "${ZLIB_INCLUDE_DIRS}")
diff --git a/libraries/logic/Commandline.cpp b/libraries/logic/Commandline.cpp
new file mode 100644
index 00000000..9a8ddbf1
--- /dev/null
+++ b/libraries/logic/Commandline.cpp
@@ -0,0 +1,483 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Commandline.h"
+
+/**
+ * @file libutil/src/cmdutils.cpp
+ */
+
+namespace Commandline
+{
+
+// commandline splitter
+QStringList splitArgs(QString args)
+{
+	QStringList argv;
+	QString current;
+	bool escape = false;
+	QChar inquotes;
+	for (int i = 0; i < args.length(); i++)
+	{
+		QChar cchar = args.at(i);
+
+		// \ escaped
+		if (escape)
+		{
+			current += cchar;
+			escape = false;
+			// in "quotes"
+		}
+		else if (!inquotes.isNull())
+		{
+			if (cchar == 0x5C)
+				escape = true;
+			else if (cchar == inquotes)
+				inquotes = 0;
+			else
+				current += cchar;
+			// otherwise
+		}
+		else
+		{
+			if (cchar == 0x20)
+			{
+				if (!current.isEmpty())
+				{
+					argv << current;
+					current.clear();
+				}
+			}
+			else if (cchar == 0x22 || cchar == 0x27)
+				inquotes = cchar;
+			else
+				current += cchar;
+		}
+	}
+	if (!current.isEmpty())
+		argv << current;
+	return argv;
+}
+
+Parser::Parser(FlagStyle::Enum flagStyle, ArgumentStyle::Enum argStyle)
+{
+	m_flagStyle = flagStyle;
+	m_argStyle = argStyle;
+}
+
+// styles setter/getter
+void Parser::setArgumentStyle(ArgumentStyle::Enum style)
+{
+	m_argStyle = style;
+}
+ArgumentStyle::Enum Parser::argumentStyle()
+{
+	return m_argStyle;
+}
+
+void Parser::setFlagStyle(FlagStyle::Enum style)
+{
+	m_flagStyle = style;
+}
+FlagStyle::Enum Parser::flagStyle()
+{
+	return m_flagStyle;
+}
+
+// setup methods
+void Parser::addSwitch(QString name, bool def)
+{
+	if (m_params.contains(name))
+		throw "Name not unique";
+
+	OptionDef *param = new OptionDef;
+	param->type = otSwitch;
+	param->name = name;
+	param->metavar = QString("<%1>").arg(name);
+	param->def = def;
+
+	m_options[name] = param;
+	m_params[name] = (CommonDef *)param;
+	m_optionList.append(param);
+}
+
+void Parser::addOption(QString name, QVariant def)
+{
+	if (m_params.contains(name))
+		throw "Name not unique";
+
+	OptionDef *param = new OptionDef;
+	param->type = otOption;
+	param->name = name;
+	param->metavar = QString("<%1>").arg(name);
+	param->def = def;
+
+	m_options[name] = param;
+	m_params[name] = (CommonDef *)param;
+	m_optionList.append(param);
+}
+
+void Parser::addArgument(QString name, bool required, QVariant def)
+{
+	if (m_params.contains(name))
+		throw "Name not unique";
+
+	PositionalDef *param = new PositionalDef;
+	param->name = name;
+	param->def = def;
+	param->required = required;
+	param->metavar = name;
+
+	m_positionals.append(param);
+	m_params[name] = (CommonDef *)param;
+}
+
+void Parser::addDocumentation(QString name, QString doc, QString metavar)
+{
+	if (!m_params.contains(name))
+		throw "Name does not exist";
+
+	CommonDef *param = m_params[name];
+	param->doc = doc;
+	if (!metavar.isNull())
+		param->metavar = metavar;
+}
+
+void Parser::addShortOpt(QString name, QChar flag)
+{
+	if (!m_params.contains(name))
+		throw "Name does not exist";
+	if (!m_options.contains(name))
+		throw "Name is not an Option or Swtich";
+
+	OptionDef *param = m_options[name];
+	m_flags[flag] = param;
+	param->flag = flag;
+}
+
+// help methods
+QString Parser::compileHelp(QString progName, int helpIndent, bool useFlags)
+{
+	QStringList help;
+	help << compileUsage(progName, useFlags) << "\r\n";
+
+	// positionals
+	if (!m_positionals.isEmpty())
+	{
+		help << "\r\n";
+		help << "Positional arguments:\r\n";
+		QListIterator<PositionalDef *> it2(m_positionals);
+		while (it2.hasNext())
+		{
+			PositionalDef *param = it2.next();
+			help << "  " << param->metavar;
+			help << " " << QString(helpIndent - param->metavar.length() - 1, ' ');
+			help << param->doc << "\r\n";
+		}
+	}
+
+	// Options
+	if (!m_optionList.isEmpty())
+	{
+		help << "\r\n";
+		QString optPrefix, flagPrefix;
+		getPrefix(optPrefix, flagPrefix);
+
+		help << "Options & Switches:\r\n";
+		QListIterator<OptionDef *> it(m_optionList);
+		while (it.hasNext())
+		{
+			OptionDef *option = it.next();
+			help << "  ";
+			int nameLength = optPrefix.length() + option->name.length();
+			if (!option->flag.isNull())
+			{
+				nameLength += 3 + flagPrefix.length();
+				help << flagPrefix << option->flag << ", ";
+			}
+			help << optPrefix << option->name;
+			if (option->type == otOption)
+			{
+				QString arg = QString("%1%2").arg(
+					((m_argStyle == ArgumentStyle::Equals) ? "=" : " "), option->metavar);
+				nameLength += arg.length();
+				help << arg;
+			}
+			help << " " << QString(helpIndent - nameLength - 1, ' ');
+			help << option->doc << "\r\n";
+		}
+	}
+
+	return help.join("");
+}
+
+QString Parser::compileUsage(QString progName, bool useFlags)
+{
+	QStringList usage;
+	usage << "Usage: " << progName;
+
+	QString optPrefix, flagPrefix;
+	getPrefix(optPrefix, flagPrefix);
+
+	// options
+	QListIterator<OptionDef *> it(m_optionList);
+	while (it.hasNext())
+	{
+		OptionDef *option = it.next();
+		usage << " [";
+		if (!option->flag.isNull() && useFlags)
+			usage << flagPrefix << option->flag;
+		else
+			usage << optPrefix << option->name;
+		if (option->type == otOption)
+			usage << ((m_argStyle == ArgumentStyle::Equals) ? "=" : " ") << option->metavar;
+		usage << "]";
+	}
+
+	// arguments
+	QListIterator<PositionalDef *> it2(m_positionals);
+	while (it2.hasNext())
+	{
+		PositionalDef *param = it2.next();
+		usage << " " << (param->required ? "<" : "[");
+		usage << param->metavar;
+		usage << (param->required ? ">" : "]");
+	}
+
+	return usage.join("");
+}
+
+// parsing
+QHash<QString, QVariant> Parser::parse(QStringList argv)
+{
+	QHash<QString, QVariant> map;
+
+	QStringListIterator it(argv);
+	QString programName = it.next();
+
+	QString optionPrefix;
+	QString flagPrefix;
+	QListIterator<PositionalDef *> positionals(m_positionals);
+	QStringList expecting;
+
+	getPrefix(optionPrefix, flagPrefix);
+
+	while (it.hasNext())
+	{
+		QString arg = it.next();
+
+		if (!expecting.isEmpty())
+		// we were expecting an argument
+		{
+			QString name = expecting.first();
+/*
+			if (map.contains(name))
+				throw ParsingError(
+					QString("Option %2%1 was given multiple times").arg(name, optionPrefix));
+*/
+			map[name] = QVariant(arg);
+
+			expecting.removeFirst();
+			continue;
+		}
+
+		if (arg.startsWith(optionPrefix))
+		// we have an option
+		{
+			// qDebug("Found option %s", qPrintable(arg));
+
+			QString name = arg.mid(optionPrefix.length());
+			QString equals;
+
+			if ((m_argStyle == ArgumentStyle::Equals ||
+				 m_argStyle == ArgumentStyle::SpaceAndEquals) &&
+				name.contains("="))
+			{
+				int i = name.indexOf("=");
+				equals = name.mid(i + 1);
+				name = name.left(i);
+			}
+
+			if (m_options.contains(name))
+			{
+				/*
+				if (map.contains(name))
+					throw ParsingError(QString("Option %2%1 was given multiple times")
+										   .arg(name, optionPrefix));
+*/
+				OptionDef *option = m_options[name];
+				if (option->type == otSwitch)
+					map[name] = true;
+				else // if (option->type == otOption)
+				{
+					if (m_argStyle == ArgumentStyle::Space)
+						expecting.append(name);
+					else if (!equals.isNull())
+						map[name] = equals;
+					else if (m_argStyle == ArgumentStyle::SpaceAndEquals)
+						expecting.append(name);
+					else
+						throw ParsingError(QString("Option %2%1 reqires an argument.")
+											   .arg(name, optionPrefix));
+				}
+
+				continue;
+			}
+
+			throw ParsingError(QString("Unknown Option %2%1").arg(name, optionPrefix));
+		}
+
+		if (arg.startsWith(flagPrefix))
+		// we have (a) flag(s)
+		{
+			// qDebug("Found flags %s", qPrintable(arg));
+
+			QString flags = arg.mid(flagPrefix.length());
+			QString equals;
+
+			if ((m_argStyle == ArgumentStyle::Equals ||
+				 m_argStyle == ArgumentStyle::SpaceAndEquals) &&
+				flags.contains("="))
+			{
+				int i = flags.indexOf("=");
+				equals = flags.mid(i + 1);
+				flags = flags.left(i);
+			}
+
+			for (int i = 0; i < flags.length(); i++)
+			{
+				QChar flag = flags.at(i);
+
+				if (!m_flags.contains(flag))
+					throw ParsingError(QString("Unknown flag %2%1").arg(flag, flagPrefix));
+
+				OptionDef *option = m_flags[flag];
+/*
+				if (map.contains(option->name))
+					throw ParsingError(QString("Option %2%1 was given multiple times")
+										   .arg(option->name, optionPrefix));
+*/
+				if (option->type == otSwitch)
+					map[option->name] = true;
+				else // if (option->type == otOption)
+				{
+					if (m_argStyle == ArgumentStyle::Space)
+						expecting.append(option->name);
+					else if (!equals.isNull())
+						if (i == flags.length() - 1)
+							map[option->name] = equals;
+						else
+							throw ParsingError(QString("Flag %4%2 of Argument-requiring Option "
+													   "%1 not last flag in %4%3")
+												   .arg(option->name, flag, flags, flagPrefix));
+					else if (m_argStyle == ArgumentStyle::SpaceAndEquals)
+						expecting.append(option->name);
+					else
+						throw ParsingError(QString("Option %1 reqires an argument. (flag %3%2)")
+											   .arg(option->name, flag, flagPrefix));
+				}
+			}
+
+			continue;
+		}
+
+		// must be a positional argument
+		if (!positionals.hasNext())
+			throw ParsingError(QString("Don't know what to do with '%1'").arg(arg));
+
+		PositionalDef *param = positionals.next();
+
+		map[param->name] = arg;
+	}
+
+	// check if we're missing something
+	if (!expecting.isEmpty())
+		throw ParsingError(QString("Was still expecting arguments for %2%1").arg(
+			expecting.join(QString(", ") + optionPrefix), optionPrefix));
+
+	while (positionals.hasNext())
+	{
+		PositionalDef *param = positionals.next();
+		if (param->required)
+			throw ParsingError(
+				QString("Missing required positional argument '%1'").arg(param->name));
+		else
+			map[param->name] = param->def;
+	}
+
+	// fill out gaps
+	QListIterator<OptionDef *> iter(m_optionList);
+	while (iter.hasNext())
+	{
+		OptionDef *option = iter.next();
+		if (!map.contains(option->name))
+			map[option->name] = option->def;
+	}
+
+	return map;
+}
+
+// clear defs
+void Parser::clear()
+{
+	m_flags.clear();
+	m_params.clear();
+	m_options.clear();
+
+	QMutableListIterator<OptionDef *> it(m_optionList);
+	while (it.hasNext())
+	{
+		OptionDef *option = it.next();
+		it.remove();
+		delete option;
+	}
+
+	QMutableListIterator<PositionalDef *> it2(m_positionals);
+	while (it2.hasNext())
+	{
+		PositionalDef *arg = it2.next();
+		it2.remove();
+		delete arg;
+	}
+}
+
+// Destructor
+Parser::~Parser()
+{
+	clear();
+}
+
+// getPrefix
+void Parser::getPrefix(QString &opt, QString &flag)
+{
+	if (m_flagStyle == FlagStyle::Windows)
+		opt = flag = "/";
+	else if (m_flagStyle == FlagStyle::Unix)
+		opt = flag = "-";
+	// else if (m_flagStyle == FlagStyle::GNU)
+	else
+	{
+		opt = "--";
+		flag = "-";
+	}
+}
+
+// ParsingError
+ParsingError::ParsingError(const QString &what) : std::runtime_error(what.toStdString())
+{
+}
+}
\ No newline at end of file
diff --git a/libraries/logic/Commandline.h b/libraries/logic/Commandline.h
new file mode 100644
index 00000000..bee02bad
--- /dev/null
+++ b/libraries/logic/Commandline.h
@@ -0,0 +1,252 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <exception>
+#include <stdexcept>
+
+#include <QString>
+#include <QVariant>
+#include <QHash>
+#include <QStringList>
+
+#include "multimc_logic_export.h"
+
+/**
+ * @file libutil/include/cmdutils.h
+ * @brief commandline parsing and processing utilities
+ */
+
+namespace Commandline
+{
+
+/**
+ * @brief split a string into argv items like a shell would do
+ * @param args the argument string
+ * @return a QStringList containing all arguments
+ */
+MULTIMC_LOGIC_EXPORT QStringList splitArgs(QString args);
+
+/**
+ * @brief The FlagStyle enum
+ * Specifies how flags are decorated
+ */
+
+namespace FlagStyle
+{
+enum Enum
+{
+	GNU,	 /**< --option and -o (GNU Style) */
+	Unix,	/**< -option and -o  (Unix Style) */
+	Windows, /**< /option and /o  (Windows Style) */
+#ifdef Q_OS_WIN32
+	Default = Windows
+#else
+		Default = GNU
+#endif
+};
+}
+
+/**
+ * @brief The ArgumentStyle enum
+ */
+namespace ArgumentStyle
+{
+enum Enum
+{
+	Space,		  /**< --option=value */
+	Equals,		 /**< --option value */
+	SpaceAndEquals, /**< --option[= ]value */
+#ifdef Q_OS_WIN32
+	Default = Equals
+#else
+		Default = SpaceAndEquals
+#endif
+};
+}
+
+/**
+ * @brief The ParsingError class
+ */
+class MULTIMC_LOGIC_EXPORT ParsingError : public std::runtime_error
+{
+public:
+	ParsingError(const QString &what);
+};
+
+/**
+ * @brief The Parser class
+ */
+class MULTIMC_LOGIC_EXPORT Parser
+{
+public:
+	/**
+	 * @brief Parser constructor
+	 * @param flagStyle the FlagStyle to use in this Parser
+	 * @param argStyle the ArgumentStyle to use in this Parser
+	 */
+	Parser(FlagStyle::Enum flagStyle = FlagStyle::Default,
+		   ArgumentStyle::Enum argStyle = ArgumentStyle::Default);
+
+	/**
+	 * @brief set the flag style
+	 * @param style
+	 */
+	void setFlagStyle(FlagStyle::Enum style);
+
+	/**
+	 * @brief get the flag style
+	 * @return
+	 */
+	FlagStyle::Enum flagStyle();
+
+	/**
+	 * @brief set the argument style
+	 * @param style
+	 */
+	void setArgumentStyle(ArgumentStyle::Enum style);
+
+	/**
+	 * @brief get the argument style
+	 * @return
+	 */
+	ArgumentStyle::Enum argumentStyle();
+
+	/**
+	 * @brief define a boolean switch
+	 * @param name the parameter name
+	 * @param def the default value
+	 */
+	void addSwitch(QString name, bool def = false);
+
+	/**
+	 * @brief define an option that takes an additional argument
+	 * @param name the parameter name
+	 * @param def the default value
+	 */
+	void addOption(QString name, QVariant def = QVariant());
+
+	/**
+	 * @brief define a positional argument
+	 * @param name the parameter name
+	 * @param required wether this argument is required
+	 * @param def the default value
+	 */
+	void addArgument(QString name, bool required = true, QVariant def = QVariant());
+
+	/**
+	 * @brief adds a flag to an existing parameter
+	 * @param name the (existing) parameter name
+	 * @param flag the flag character
+	 * @see addSwitch addArgument addOption
+	 * Note: any one parameter can only have one flag
+	 */
+	void addShortOpt(QString name, QChar flag);
+
+	/**
+	 * @brief adds documentation to a Parameter
+	 * @param name the parameter name
+	 * @param metavar a string to be displayed as placeholder for the value
+	 * @param doc a QString containing the documentation
+	 * Note: on positional arguments, metavar replaces the name as displayed.
+	 *       on options , metavar replaces the value placeholder
+	 */
+	void addDocumentation(QString name, QString doc, QString metavar = QString());
+
+	/**
+	 * @brief generate a help message
+	 * @param progName the program name to use in the help message
+	 * @param helpIndent how much the parameter documentation should be indented
+	 * @param flagsInUsage whether we should use flags instead of options in the usage
+	 * @return a help message
+	 */
+	QString compileHelp(QString progName, int helpIndent = 22, bool flagsInUsage = true);
+
+	/**
+	 * @brief generate a short usage message
+	 * @param progName the program name to use in the usage message
+	 * @param useFlags whether we should use flags instead of options
+	 * @return a usage message
+	 */
+	QString compileUsage(QString progName, bool useFlags = true);
+
+	/**
+	 * @brief parse
+	 * @param argv a QStringList containing the program ARGV
+	 * @return a QHash mapping argument names to their values
+	 */
+	QHash<QString, QVariant> parse(QStringList argv);
+
+	/**
+	 * @brief clear all definitions
+	 */
+	void clear();
+
+	~Parser();
+
+private:
+	FlagStyle::Enum m_flagStyle;
+	ArgumentStyle::Enum m_argStyle;
+
+	enum OptionType
+	{
+		otSwitch,
+		otOption
+	};
+
+	// Important: the common part MUST BE COMMON ON ALL THREE structs
+	struct CommonDef
+	{
+		QString name;
+		QString doc;
+		QString metavar;
+		QVariant def;
+	};
+
+	struct OptionDef
+	{
+		// common
+		QString name;
+		QString doc;
+		QString metavar;
+		QVariant def;
+		// option
+		OptionType type;
+		QChar flag;
+	};
+
+	struct PositionalDef
+	{
+		// common
+		QString name;
+		QString doc;
+		QString metavar;
+		QVariant def;
+		// positional
+		bool required;
+	};
+
+	QHash<QString, OptionDef *> m_options;
+	QHash<QChar, OptionDef *> m_flags;
+	QHash<QString, CommonDef *> m_params;
+	QList<PositionalDef *> m_positionals;
+	QList<OptionDef *> m_optionList;
+
+	void getPrefix(QString &opt, QString &flag);
+};
+}
diff --git a/libraries/logic/DefaultVariable.h b/libraries/logic/DefaultVariable.h
new file mode 100644
index 00000000..38d7ecc2
--- /dev/null
+++ b/libraries/logic/DefaultVariable.h
@@ -0,0 +1,35 @@
+#pragma once
+
+template <typename T>
+class DefaultVariable
+{
+public:
+	DefaultVariable(const T & value)
+	{
+		defaultValue = value;
+	}
+	DefaultVariable<T> & operator =(const T & value)
+	{
+		currentValue = value;
+		is_default = currentValue == defaultValue;
+		is_explicit = true;
+		return *this;
+	}
+	operator const T &() const
+	{
+		return is_default ? defaultValue : currentValue;
+	}
+	bool isDefault() const
+	{
+		return is_default;
+	}
+	bool isExplicit() const
+	{
+		return is_explicit;
+	}
+private:
+	T currentValue;
+	T defaultValue;
+	bool is_default = true;
+	bool is_explicit = false;
+};
diff --git a/libraries/logic/Env.cpp b/libraries/logic/Env.cpp
new file mode 100644
index 00000000..cc0c5981
--- /dev/null
+++ b/libraries/logic/Env.cpp
@@ -0,0 +1,222 @@
+#include "Env.h"
+#include "net/HttpMetaCache.h"
+#include "BaseVersion.h"
+#include "BaseVersionList.h"
+#include <QDir>
+#include <QNetworkProxy>
+#include <QNetworkAccessManager>
+#include <QDebug>
+#include "tasks/Task.h"
+#include "wonko/WonkoIndex.h"
+#include <QDebug>
+
+/*
+ * The *NEW* global rat nest of an object. Handle with care.
+ */
+
+Env::Env()
+{
+	m_qnam = std::make_shared<QNetworkAccessManager>();
+}
+
+void Env::destroy()
+{
+	m_metacache.reset();
+	m_qnam.reset();
+	m_versionLists.clear();
+}
+
+Env& Env::Env::getInstance()
+{
+	static Env instance;
+	return instance;
+}
+
+std::shared_ptr< HttpMetaCache > Env::metacache()
+{
+	Q_ASSERT(m_metacache != nullptr);
+	return m_metacache;
+}
+
+std::shared_ptr< QNetworkAccessManager > Env::qnam()
+{
+	return m_qnam;
+}
+
+/*
+class NullVersion : public BaseVersion
+{
+	Q_OBJECT
+public:
+	virtual QString name()
+	{
+		return "null";
+	}
+	virtual QString descriptor()
+	{
+		return "null";
+	}
+	virtual QString typeString() const
+	{
+		return "Null";
+	}
+};
+
+class NullTask: public Task
+{
+	Q_OBJECT
+public:
+	virtual void executeTask()
+	{
+		emitFailed(tr("Nothing to do."));
+	}
+};
+
+class NullVersionList: public BaseVersionList
+{
+	Q_OBJECT
+public:
+	virtual const BaseVersionPtr at(int i) const
+	{
+		return std::make_shared<NullVersion>();
+	}
+	virtual int count() const
+	{
+		return 0;
+	};
+	virtual Task* getLoadTask()
+	{
+		return new NullTask;
+	}
+	virtual bool isLoaded()
+	{
+		return false;
+	}
+	virtual void sort()
+	{
+	}
+	virtual void updateListData(QList< BaseVersionPtr >)
+	{
+	}
+};
+*/
+
+BaseVersionPtr Env::getVersion(QString component, QString version)
+{
+	auto list = getVersionList(component);
+	if(!list)
+	{
+		return nullptr;
+	}
+	return list->findVersion(version);
+}
+
+std::shared_ptr< BaseVersionList > Env::getVersionList(QString component)
+{
+	auto iter = m_versionLists.find(component);
+	if(iter != m_versionLists.end())
+	{
+		return *iter;
+	}
+	//return std::make_shared<NullVersionList>();
+	return nullptr;
+}
+
+void Env::registerVersionList(QString name, std::shared_ptr< BaseVersionList > vlist)
+{
+	m_versionLists[name] = vlist;
+}
+
+std::shared_ptr<WonkoIndex> Env::wonkoIndex()
+{
+	if (!m_wonkoIndex)
+	{
+		m_wonkoIndex = std::make_shared<WonkoIndex>();
+	}
+	return m_wonkoIndex;
+}
+
+
+void Env::initHttpMetaCache()
+{
+	m_metacache.reset(new HttpMetaCache("metacache"));
+	m_metacache->addBase("asset_indexes", QDir("assets/indexes").absolutePath());
+	m_metacache->addBase("asset_objects", QDir("assets/objects").absolutePath());
+	m_metacache->addBase("versions", QDir("versions").absolutePath());
+	m_metacache->addBase("libraries", QDir("libraries").absolutePath());
+	m_metacache->addBase("minecraftforge", QDir("mods/minecraftforge").absolutePath());
+	m_metacache->addBase("fmllibs", QDir("mods/minecraftforge/libs").absolutePath());
+	m_metacache->addBase("liteloader", QDir("mods/liteloader").absolutePath());
+	m_metacache->addBase("general", QDir("cache").absolutePath());
+	m_metacache->addBase("skins", QDir("accounts/skins").absolutePath());
+	m_metacache->addBase("root", QDir::currentPath());
+	m_metacache->addBase("translations", QDir("translations").absolutePath());
+	m_metacache->addBase("icons", QDir("cache/icons").absolutePath());
+	m_metacache->addBase("wonko", QDir("cache/wonko").absolutePath());
+	m_metacache->Load();
+}
+
+void Env::updateProxySettings(QString proxyTypeStr, QString addr, int port, QString user, QString password)
+{
+	// Set the application proxy settings.
+	if (proxyTypeStr == "SOCKS5")
+	{
+		QNetworkProxy::setApplicationProxy(
+			QNetworkProxy(QNetworkProxy::Socks5Proxy, addr, port, user, password));
+	}
+	else if (proxyTypeStr == "HTTP")
+	{
+		QNetworkProxy::setApplicationProxy(
+			QNetworkProxy(QNetworkProxy::HttpProxy, addr, port, user, password));
+	}
+	else if (proxyTypeStr == "None")
+	{
+		// If we have no proxy set, set no proxy and return.
+		QNetworkProxy::setApplicationProxy(QNetworkProxy(QNetworkProxy::NoProxy));
+	}
+	else
+	{
+		// If we have "Default" selected, set Qt to use the system proxy settings.
+		QNetworkProxyFactory::setUseSystemConfiguration(true);
+	}
+
+	qDebug() << "Detecting proxy settings...";
+	QNetworkProxy proxy = QNetworkProxy::applicationProxy();
+	if (m_qnam.get())
+		m_qnam->setProxy(proxy);
+	QString proxyDesc;
+	if (proxy.type() == QNetworkProxy::NoProxy)
+	{
+		qDebug() << "Using no proxy is an option!";
+		return;
+	}
+	switch (proxy.type())
+	{
+	case QNetworkProxy::DefaultProxy:
+		proxyDesc = "Default proxy: ";
+		break;
+	case QNetworkProxy::Socks5Proxy:
+		proxyDesc = "Socks5 proxy: ";
+		break;
+	case QNetworkProxy::HttpProxy:
+		proxyDesc = "HTTP proxy: ";
+		break;
+	case QNetworkProxy::HttpCachingProxy:
+		proxyDesc = "HTTP caching: ";
+		break;
+	case QNetworkProxy::FtpCachingProxy:
+		proxyDesc = "FTP caching: ";
+		break;
+	default:
+		proxyDesc = "DERP proxy: ";
+		break;
+	}
+	proxyDesc += QString("%3@%1:%2 pass %4")
+					 .arg(proxy.hostName())
+					 .arg(proxy.port())
+					 .arg(proxy.user())
+					 .arg(proxy.password());
+	qDebug() << proxyDesc;
+}
+
+#include "Env.moc"
diff --git a/libraries/logic/Env.h b/libraries/logic/Env.h
new file mode 100644
index 00000000..4d8945d7
--- /dev/null
+++ b/libraries/logic/Env.h
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <memory>
+#include <QString>
+#include <QMap>
+
+#include "multimc_logic_export.h"
+
+class QNetworkAccessManager;
+class HttpMetaCache;
+class BaseVersionList;
+class BaseVersion;
+class WonkoIndex;
+
+#if defined(ENV)
+	#undef ENV
+#endif
+#define ENV (Env::getInstance())
+
+class MULTIMC_LOGIC_EXPORT Env
+{
+	friend class MultiMC;
+private:
+	Env();
+public:
+	static Env& getInstance();
+
+	// call when Qt stuff is being torn down
+	void destroy();
+
+	std::shared_ptr<QNetworkAccessManager> qnam();
+
+	std::shared_ptr<HttpMetaCache> metacache();
+
+	/// init the cache. FIXME: possible future hook point
+	void initHttpMetaCache();
+
+	/// Updates the application proxy settings from the settings object.
+	void updateProxySettings(QString proxyTypeStr, QString addr, int port, QString user, QString password);
+
+	/// get a version list by name
+	std::shared_ptr<BaseVersionList> getVersionList(QString component);
+
+	/// get a version by list name and version name
+	std::shared_ptr<BaseVersion> getVersion(QString component, QString version);
+
+	void registerVersionList(QString name, std::shared_ptr<BaseVersionList> vlist);
+
+	std::shared_ptr<WonkoIndex> wonkoIndex();
+
+	QString wonkoRootUrl() const { return m_wonkoRootUrl; }
+	void setWonkoRootUrl(const QString &url) { m_wonkoRootUrl = url; }
+
+protected:
+	std::shared_ptr<QNetworkAccessManager> m_qnam;
+	std::shared_ptr<HttpMetaCache> m_metacache;
+	QMap<QString, std::shared_ptr<BaseVersionList>> m_versionLists;
+	std::shared_ptr<WonkoIndex> m_wonkoIndex;
+	QString m_wonkoRootUrl;
+};
diff --git a/libraries/logic/Exception.h b/libraries/logic/Exception.h
new file mode 100644
index 00000000..30c7aa45
--- /dev/null
+++ b/libraries/logic/Exception.h
@@ -0,0 +1,34 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include <QString>
+#include <QDebug>
+#include <exception>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT Exception : public std::exception
+{
+public:
+	Exception(const QString &message) : std::exception(), m_message(message)
+	{
+		qCritical() << "Exception:" << message;
+	}
+	Exception(const Exception &other)
+		: std::exception(), m_message(other.cause())
+	{
+	}
+	virtual ~Exception() noexcept {}
+	const char *what() const noexcept
+	{
+		return m_message.toLatin1().constData();
+	}
+	QString cause() const
+	{
+		return m_message;
+	}
+
+private:
+	QString m_message;
+};
diff --git a/libraries/logic/FileSystem.cpp b/libraries/logic/FileSystem.cpp
new file mode 100644
index 00000000..049f1e38
--- /dev/null
+++ b/libraries/logic/FileSystem.cpp
@@ -0,0 +1,436 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "FileSystem.h"
+
+#include <QDir>
+#include <QSaveFile>
+#include <QFileInfo>
+#include <QDebug>
+#include <QUrl>
+#include <QStandardPaths>
+
+namespace FS {
+
+void ensureExists(const QDir &dir)
+{
+	if (!QDir().mkpath(dir.absolutePath()))
+	{
+		throw FileSystemException("Unable to create directory " + dir.dirName() + " (" +
+									  dir.absolutePath() + ")");
+	}
+}
+
+void write(const QString &filename, const QByteArray &data)
+{
+	ensureExists(QFileInfo(filename).dir());
+	QSaveFile file(filename);
+	if (!file.open(QSaveFile::WriteOnly))
+	{
+		throw FileSystemException("Couldn't open " + filename + " for writing: " +
+								  file.errorString());
+	}
+	if (data.size() != file.write(data))
+	{
+		throw FileSystemException("Error writing data to " + filename + ": " +
+								  file.errorString());
+	}
+	if (!file.commit())
+	{
+		throw FileSystemException("Error while committing data to " + filename + ": " +
+								  file.errorString());
+	}
+}
+
+QByteArray read(const QString &filename)
+{
+	QFile file(filename);
+	if (!file.open(QFile::ReadOnly))
+	{
+		throw FileSystemException("Unable to open " + filename + " for reading: " +
+								  file.errorString());
+	}
+	const qint64 size = file.size();
+	QByteArray data(int(size), 0);
+	const qint64 ret = file.read(data.data(), size);
+	if (ret == -1 || ret != size)
+	{
+		throw FileSystemException("Error reading data from " + filename + ": " +
+								  file.errorString());
+	}
+	return data;
+}
+
+bool ensureFilePathExists(QString filenamepath)
+{
+	QFileInfo a(filenamepath);
+	QDir dir;
+	QString ensuredPath = a.path();
+	bool success = dir.mkpath(ensuredPath);
+	return success;
+}
+
+bool ensureFolderPathExists(QString foldernamepath)
+{
+	QFileInfo a(foldernamepath);
+	QDir dir;
+	QString ensuredPath = a.filePath();
+	bool success = dir.mkpath(ensuredPath);
+	return success;
+}
+
+bool copy::operator()(const QString &offset)
+{
+	//NOTE always deep copy on windows. the alternatives are too messy.
+	#if defined Q_OS_WIN32
+	m_followSymlinks = true;
+	#endif
+
+	auto src = PathCombine(m_src.absolutePath(), offset);
+	auto dst = PathCombine(m_dst.absolutePath(), offset);
+
+	QFileInfo currentSrc(src);
+	if (!currentSrc.exists())
+		return false;
+
+	if(!m_followSymlinks && currentSrc.isSymLink())
+	{
+		qDebug() << "creating symlink" << src << " - " << dst;
+		if (!ensureFilePathExists(dst))
+		{
+			qWarning() << "Cannot create path!";
+			return false;
+		}
+		return QFile::link(currentSrc.symLinkTarget(), dst);
+	}
+	else if(currentSrc.isFile())
+	{
+		qDebug() << "copying file" << src << " - " << dst;
+		if (!ensureFilePathExists(dst))
+		{
+			qWarning() << "Cannot create path!";
+			return false;
+		}
+		return QFile::copy(src, dst);
+	}
+	else if(currentSrc.isDir())
+	{
+		qDebug() << "recursing" << offset;
+		if (!ensureFolderPathExists(dst))
+		{
+			qWarning() << "Cannot create path!";
+			return false;
+		}
+		QDir currentDir(src);
+		for(auto & f : currentDir.entryList(QDir::Files | QDir::Dirs | QDir::NoDotAndDotDot | QDir::Hidden | QDir::System))
+		{
+			auto inner_offset = PathCombine(offset, f);
+			// ignore and skip stuff that matches the blacklist.
+			if(m_blacklist && m_blacklist->matches(inner_offset))
+			{
+				continue;
+			}
+			if(!operator()(inner_offset))
+			{
+				return false;
+			}
+		}
+	}
+	else
+	{
+		qCritical() << "Copy ERROR: Unknown filesystem object:" << src;
+		return false;
+	}
+	return true;
+}
+
+
+#if defined Q_OS_WIN32
+#include <windows.h>
+#include <string>
+#endif
+bool deletePath(QString path)
+{
+	bool OK = true;
+	QDir dir(path);
+
+	if (!dir.exists())
+	{
+		return OK;
+	}
+	auto allEntries = dir.entryInfoList(QDir::NoDotAndDotDot | QDir::System | QDir::Hidden |
+										QDir::AllDirs | QDir::Files,
+										QDir::DirsFirst);
+
+	for(auto & info: allEntries)
+	{
+#if defined Q_OS_WIN32
+		QString nativePath = QDir::toNativeSeparators(info.absoluteFilePath());
+		auto wString = nativePath.toStdWString();
+		DWORD dwAttrs = GetFileAttributesW(wString.c_str());
+		// Windows: check for junctions, reparse points and other nasty things of that sort
+		if(dwAttrs & FILE_ATTRIBUTE_REPARSE_POINT)
+		{
+			if (info.isFile())
+			{
+				OK &= QFile::remove(info.absoluteFilePath());
+			}
+			else if (info.isDir())
+			{
+				OK &= dir.rmdir(info.absoluteFilePath());
+			}
+		}
+#else
+		// We do not trust Qt with reparse points, but do trust it with unix symlinks.
+		if(info.isSymLink())
+		{
+			OK &= QFile::remove(info.absoluteFilePath());
+		}
+#endif
+		else if (info.isDir())
+		{
+			OK &= deletePath(info.absoluteFilePath());
+		}
+		else if (info.isFile())
+		{
+			OK &= QFile::remove(info.absoluteFilePath());
+		}
+		else
+		{
+			OK = false;
+			qCritical() << "Delete ERROR: Unknown filesystem object:" << info.absoluteFilePath();
+		}
+	}
+	OK &= dir.rmdir(dir.absolutePath());
+	return OK;
+}
+
+
+QString PathCombine(QString path1, QString path2)
+{
+	if(!path1.size())
+		return path2;
+	if(!path2.size())
+		return path1;
+    return QDir::cleanPath(path1 + QDir::separator() + path2);
+}
+
+QString PathCombine(QString path1, QString path2, QString path3)
+{
+	return PathCombine(PathCombine(path1, path2), path3);
+}
+
+QString AbsolutePath(QString path)
+{
+	return QFileInfo(path).absolutePath();
+}
+
+QString ResolveExecutable(QString path)
+{
+	if (path.isEmpty())
+	{
+		return QString();
+	}
+	if(!path.contains('/'))
+	{
+		path = QStandardPaths::findExecutable(path);
+	}
+	QFileInfo pathInfo(path);
+	if(!pathInfo.exists() || !pathInfo.isExecutable())
+	{
+		return QString();
+	}
+	return pathInfo.absoluteFilePath();
+}
+
+/**
+ * Normalize path
+ *
+ * Any paths inside the current directory will be normalized to relative paths (to current)
+ * Other paths will be made absolute
+ */
+QString NormalizePath(QString path)
+{
+	QDir a = QDir::currentPath();
+	QString currentAbsolute = a.absolutePath();
+
+	QDir b(path);
+	QString newAbsolute = b.absolutePath();
+
+	if (newAbsolute.startsWith(currentAbsolute))
+	{
+		return a.relativeFilePath(newAbsolute);
+	}
+	else
+	{
+		return newAbsolute;
+	}
+}
+
+QString badFilenameChars = "\"\\/?<>:*|!";
+
+QString RemoveInvalidFilenameChars(QString string, QChar replaceWith)
+{
+	for (int i = 0; i < string.length(); i++)
+	{
+		if (badFilenameChars.contains(string[i]))
+		{
+			string[i] = replaceWith;
+		}
+	}
+	return string;
+}
+
+QString DirNameFromString(QString string, QString inDir)
+{
+	int num = 0;
+	QString baseName = RemoveInvalidFilenameChars(string, '-');
+	QString dirName;
+	do
+	{
+		if(num == 0)
+		{
+			dirName = baseName;
+		}
+		else
+		{
+			dirName = baseName + QString::number(num);;
+		}
+
+		// If it's over 9000
+		if (num > 9000)
+			return "";
+		num++;
+	} while (QFileInfo(PathCombine(inDir, dirName)).exists());
+	return dirName;
+}
+
+// Does the directory path contain any '!'? If yes, return true, otherwise false.
+// (This is a problem for Java)
+bool checkProblemticPathJava(QDir folder)
+{
+	QString pathfoldername = folder.absolutePath();
+	return pathfoldername.contains("!", Qt::CaseInsensitive);
+}
+
+#include <QStandardPaths>
+#include <QFile>
+#include <QTextStream>
+
+// Win32 crap
+#if defined Q_OS_WIN
+
+#include <windows.h>
+#include <winnls.h>
+#include <shobjidl.h>
+#include <objbase.h>
+#include <objidl.h>
+#include <shlguid.h>
+#include <shlobj.h>
+
+bool called_coinit = false;
+
+HRESULT CreateLink(LPCSTR linkPath, LPCSTR targetPath, LPCSTR args)
+{
+	HRESULT hres;
+
+	if (!called_coinit)
+	{
+		hres = CoInitialize(NULL);
+		called_coinit = true;
+
+		if (!SUCCEEDED(hres))
+		{
+			qWarning("Failed to initialize COM. Error 0x%08X", hres);
+			return hres;
+		}
+	}
+
+	IShellLink *link;
+	hres = CoCreateInstance(CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, IID_IShellLink,
+							(LPVOID *)&link);
+
+	if (SUCCEEDED(hres))
+	{
+		IPersistFile *persistFile;
+
+		link->SetPath(targetPath);
+		link->SetArguments(args);
+
+		hres = link->QueryInterface(IID_IPersistFile, (LPVOID *)&persistFile);
+		if (SUCCEEDED(hres))
+		{
+			WCHAR wstr[MAX_PATH];
+
+			MultiByteToWideChar(CP_ACP, 0, linkPath, -1, wstr, MAX_PATH);
+
+			hres = persistFile->Save(wstr, TRUE);
+			persistFile->Release();
+		}
+		link->Release();
+	}
+	return hres;
+}
+
+#endif
+
+QString getDesktopDir()
+{
+	return QStandardPaths::writableLocation(QStandardPaths::DesktopLocation);
+}
+
+// Cross-platform Shortcut creation
+bool createShortCut(QString location, QString dest, QStringList args, QString name,
+						  QString icon)
+{
+#if defined Q_OS_LINUX
+	location = PathCombine(location, name + ".desktop");
+
+	QFile f(location);
+	f.open(QIODevice::WriteOnly | QIODevice::Text);
+	QTextStream stream(&f);
+
+	QString argstring;
+	if (!args.empty())
+		argstring = " '" + args.join("' '") + "'";
+
+	stream << "[Desktop Entry]"
+		   << "\n";
+	stream << "Type=Application"
+		   << "\n";
+	stream << "TryExec=" << dest.toLocal8Bit() << "\n";
+	stream << "Exec=" << dest.toLocal8Bit() << argstring.toLocal8Bit() << "\n";
+	stream << "Name=" << name.toLocal8Bit() << "\n";
+	stream << "Icon=" << icon.toLocal8Bit() << "\n";
+
+	stream.flush();
+	f.close();
+
+	f.setPermissions(f.permissions() | QFileDevice::ExeOwner | QFileDevice::ExeGroup |
+					 QFileDevice::ExeOther);
+
+	return true;
+#elif defined Q_OS_WIN
+	// TODO: Fix
+	//	QFile file(PathCombine(location, name + ".lnk"));
+	//	WCHAR *file_w;
+	//	WCHAR *dest_w;
+	//	WCHAR *args_w;
+	//	file.fileName().toWCharArray(file_w);
+	//	dest.toWCharArray(dest_w);
+
+	//	QString argStr;
+	//	for (int i = 0; i < args.count(); i++)
+	//	{
+	//		argStr.append(args[i]);
+	//		argStr.append(" ");
+	//	}
+	//	argStr.toWCharArray(args_w);
+
+	//	return SUCCEEDED(CreateLink(file_w, dest_w, args_w));
+	return false;
+#else
+	qWarning("Desktop Shortcuts not supported on your platform!");
+	return false;
+#endif
+}
+}
diff --git a/libraries/logic/FileSystem.h b/libraries/logic/FileSystem.h
new file mode 100644
index 00000000..80637f90
--- /dev/null
+++ b/libraries/logic/FileSystem.h
@@ -0,0 +1,123 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include "Exception.h"
+#include "pathmatcher/IPathMatcher.h"
+
+#include "multimc_logic_export.h"
+#include <QDir>
+#include <QFlags>
+
+namespace FS
+{
+
+class MULTIMC_LOGIC_EXPORT FileSystemException : public ::Exception
+{
+public:
+	FileSystemException(const QString &message) : Exception(message) {}
+};
+
+/**
+ * write data to a file safely
+ */
+MULTIMC_LOGIC_EXPORT void write(const QString &filename, const QByteArray &data);
+
+/**
+ * read data from a file safely\
+ */
+MULTIMC_LOGIC_EXPORT QByteArray read(const QString &filename);
+
+/**
+ * Creates all the folders in a path for the specified path
+ * last segment of the path is treated as a file name and is ignored!
+ */
+MULTIMC_LOGIC_EXPORT bool ensureFilePathExists(QString filenamepath);
+
+/**
+ * Creates all the folders in a path for the specified path
+ * last segment of the path is treated as a folder name and is created!
+ */
+MULTIMC_LOGIC_EXPORT bool ensureFolderPathExists(QString filenamepath);
+
+class MULTIMC_LOGIC_EXPORT copy
+{
+public:
+	copy(const copy&) = delete;
+	copy(const QString & src, const QString & dst)
+	{
+		m_src = src;
+		m_dst = dst;
+	}
+	copy & followSymlinks(const bool follow)
+	{
+		m_followSymlinks = follow;
+		return *this;
+	}
+	copy & blacklist(const IPathMatcher * filter)
+	{
+		m_blacklist = filter;
+		return *this;
+	}
+	bool operator()()
+	{
+		return operator()(QString());
+	}
+
+private:
+	bool operator()(const QString &offset);
+
+private:
+	bool m_followSymlinks = true;
+	const IPathMatcher * m_blacklist = nullptr;
+	QDir m_src;
+	QDir m_dst;
+};
+
+/**
+ * Delete a folder recursively
+ */
+MULTIMC_LOGIC_EXPORT bool deletePath(QString path);
+
+MULTIMC_LOGIC_EXPORT QString PathCombine(QString path1, QString path2);
+MULTIMC_LOGIC_EXPORT QString PathCombine(QString path1, QString path2, QString path3);
+
+MULTIMC_LOGIC_EXPORT QString AbsolutePath(QString path);
+
+/**
+ * Resolve an executable
+ *
+ * Will resolve:
+ *   single executable (by name)
+ *   relative path
+ *   absolute path
+ *
+ * @return absolute path to executable or null string
+ */
+MULTIMC_LOGIC_EXPORT QString ResolveExecutable(QString path);
+
+/**
+ * Normalize path
+ *
+ * Any paths inside the current directory will be normalized to relative paths (to current)
+ * Other paths will be made absolute
+ *
+ * Returns false if the path logic somehow filed (and normalizedPath in invalid)
+ */
+MULTIMC_LOGIC_EXPORT QString NormalizePath(QString path);
+
+MULTIMC_LOGIC_EXPORT QString RemoveInvalidFilenameChars(QString string, QChar replaceWith = '-');
+
+MULTIMC_LOGIC_EXPORT QString DirNameFromString(QString string, QString inDir = ".");
+
+/// Checks if the a given Path contains "!"
+MULTIMC_LOGIC_EXPORT bool checkProblemticPathJava(QDir folder);
+
+// Get the Directory representing the User's Desktop
+MULTIMC_LOGIC_EXPORT QString getDesktopDir();
+
+// Create a shortcut at *location*, pointing to *dest* called with the arguments *args*
+// call it *name* and assign it the icon *icon*
+// return true if operation succeeded
+MULTIMC_LOGIC_EXPORT bool createShortCut(QString location, QString dest, QStringList args, QString name, QString iconLocation);
+}
diff --git a/libraries/logic/GZip.cpp b/libraries/logic/GZip.cpp
new file mode 100644
index 00000000..38605df6
--- /dev/null
+++ b/libraries/logic/GZip.cpp
@@ -0,0 +1,115 @@
+#include "GZip.h"
+#include <zlib.h>
+#include <QByteArray>
+
+bool GZip::unzip(const QByteArray &compressedBytes, QByteArray &uncompressedBytes)
+{
+	if (compressedBytes.size() == 0)
+	{
+		uncompressedBytes = compressedBytes;
+		return true;
+	}
+
+	unsigned uncompLength = compressedBytes.size();
+	uncompressedBytes.clear();
+	uncompressedBytes.resize(uncompLength);
+
+	z_stream strm;
+	memset(&strm, 0, sizeof(strm));
+	strm.next_in = (Bytef *)compressedBytes.data();
+	strm.avail_in = compressedBytes.size();
+
+	bool done = false;
+
+	if (inflateInit2(&strm, (16 + MAX_WBITS)) != Z_OK)
+	{
+		return false;
+	}
+
+	int err = Z_OK;
+
+	while (!done)
+	{
+		// If our output buffer is too small
+		if (strm.total_out >= uncompLength)
+		{
+			uncompressedBytes.resize(uncompLength * 2);
+			uncompLength *= 2;
+		}
+
+		strm.next_out = (Bytef *)(uncompressedBytes.data() + strm.total_out);
+		strm.avail_out = uncompLength - strm.total_out;
+
+		// Inflate another chunk.
+		err = inflate(&strm, Z_SYNC_FLUSH);
+		if (err == Z_STREAM_END)
+			done = true;
+		else if (err != Z_OK)
+		{
+			break;
+		}
+	}
+
+	if (inflateEnd(&strm) != Z_OK || !done)
+	{
+		return false;
+	}
+
+	uncompressedBytes.resize(strm.total_out);
+	return true;
+}
+
+bool GZip::zip(const QByteArray &uncompressedBytes, QByteArray &compressedBytes)
+{
+	if (uncompressedBytes.size() == 0)
+	{
+		compressedBytes = uncompressedBytes;
+		return true;
+	}
+
+	unsigned compLength = std::min(uncompressedBytes.size(), 16);
+	compressedBytes.clear();
+	compressedBytes.resize(compLength);
+
+	z_stream zs;
+	memset(&zs, 0, sizeof(zs));
+
+	if (deflateInit2(&zs, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (16 + MAX_WBITS), 8, Z_DEFAULT_STRATEGY) != Z_OK)
+	{
+		return false;
+	}
+
+	zs.next_in = (Bytef*)uncompressedBytes.data();
+	zs.avail_in = uncompressedBytes.size();
+
+	int ret;
+	compressedBytes.resize(uncompressedBytes.size());
+
+	unsigned offset = 0;
+	unsigned temp = 0;
+	do
+	{
+		auto remaining = compressedBytes.size() - offset;
+		if(remaining < 1)
+		{
+			compressedBytes.resize(compressedBytes.size() * 2);
+		}
+		zs.next_out = (Bytef *) (compressedBytes.data() + offset);
+		temp = zs.avail_out = compressedBytes.size() - offset;
+		ret = deflate(&zs, Z_FINISH);
+		offset += temp - zs.avail_out;
+	} while (ret == Z_OK);
+
+	compressedBytes.resize(offset);
+
+	if (deflateEnd(&zs) != Z_OK)
+	{
+		return false;
+	}
+
+	if (ret != Z_STREAM_END)
+	{
+		return false;
+	}
+	return true;
+}
\ No newline at end of file
diff --git a/libraries/logic/GZip.h b/libraries/logic/GZip.h
new file mode 100644
index 00000000..6993a222
--- /dev/null
+++ b/libraries/logic/GZip.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <QByteArray>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT GZip
+{
+public:
+	static bool unzip(const QByteArray &compressedBytes, QByteArray &uncompressedBytes);
+	static bool zip(const QByteArray &uncompressedBytes, QByteArray &compressedBytes);
+};
+
diff --git a/libraries/logic/InstanceList.cpp b/libraries/logic/InstanceList.cpp
new file mode 100644
index 00000000..783df660
--- /dev/null
+++ b/libraries/logic/InstanceList.cpp
@@ -0,0 +1,580 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QDir>
+#include <QSet>
+#include <QFile>
+#include <QDirIterator>
+#include <QThread>
+#include <QTextStream>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QXmlStreamReader>
+#include <QRegularExpression>
+#include <QDebug>
+
+#include "InstanceList.h"
+#include "BaseInstance.h"
+
+//FIXME: this really doesn't belong *here*
+#include "minecraft/onesix/OneSixInstance.h"
+#include "minecraft/legacy/LegacyInstance.h"
+#include "minecraft/ftb/FTBPlugin.h"
+#include "minecraft/MinecraftVersion.h"
+#include "settings/INISettingsObject.h"
+#include "NullInstance.h"
+#include "FileSystem.h"
+#include "pathmatcher/RegexpMatcher.h"
+
+const static int GROUP_FILE_FORMAT_VERSION = 1;
+
+InstanceList::InstanceList(SettingsObjectPtr globalSettings, const QString &instDir, QObject *parent)
+	: QAbstractListModel(parent), m_instDir(instDir)
+{
+	m_globalSettings = globalSettings;
+	if (!QDir::current().exists(m_instDir))
+	{
+		QDir::current().mkpath(m_instDir);
+	}
+}
+
+InstanceList::~InstanceList()
+{
+}
+
+int InstanceList::rowCount(const QModelIndex &parent) const
+{
+	Q_UNUSED(parent);
+	return m_instances.count();
+}
+
+QModelIndex InstanceList::index(int row, int column, const QModelIndex &parent) const
+{
+	Q_UNUSED(parent);
+	if (row < 0 || row >= m_instances.size())
+		return QModelIndex();
+	return createIndex(row, column, (void *)m_instances.at(row).get());
+}
+
+QVariant InstanceList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+	{
+		return QVariant();
+	}
+	BaseInstance *pdata = static_cast<BaseInstance *>(index.internalPointer());
+	switch (role)
+	{
+	case InstancePointerRole:
+	{
+		QVariant v = qVariantFromValue((void *)pdata);
+		return v;
+	}
+	case InstanceIDRole:
+    {
+        return pdata->id();
+    }
+	case Qt::DisplayRole:
+	{
+		return pdata->name();
+	}
+	case Qt::ToolTipRole:
+	{
+		return pdata->instanceRoot();
+	}
+	case Qt::DecorationRole:
+	{
+		return pdata->iconKey();
+	}
+	// HACK: see GroupView.h in gui!
+	case GroupRole:
+	{
+		return pdata->group();
+	}
+	default:
+		break;
+	}
+	return QVariant();
+}
+
+Qt::ItemFlags InstanceList::flags(const QModelIndex &index) const
+{
+	Qt::ItemFlags f;
+	if (index.isValid())
+	{
+		f |= (Qt::ItemIsEnabled | Qt::ItemIsSelectable);
+	}
+	return f;
+}
+
+void InstanceList::groupChanged()
+{
+	// save the groups. save all of them.
+	saveGroupList();
+}
+
+QStringList InstanceList::getGroups()
+{
+	return m_groups.toList();
+}
+
+void InstanceList::suspendGroupSaving()
+{
+	suspendedGroupSave = true;
+}
+
+void InstanceList::resumeGroupSaving()
+{
+	if(suspendedGroupSave)
+	{
+		suspendedGroupSave = false;
+		if(queuedGroupSave)
+		{
+			saveGroupList();
+		}
+	}
+}
+
+void InstanceList::deleteGroup(const QString& name)
+{
+	for(auto & instance: m_instances)
+	{
+		auto instGroupName = instance->group();
+		if(instGroupName == name)
+		{
+			instance->setGroupPost(QString());
+		}
+	}
+}
+
+void InstanceList::saveGroupList()
+{
+	if(suspendedGroupSave)
+	{
+		queuedGroupSave = true;
+		return;
+	}
+
+	QString groupFileName = m_instDir + "/instgroups.json";
+	QMap<QString, QSet<QString>> groupMap;
+	for (auto instance : m_instances)
+	{
+		QString id = instance->id();
+		QString group = instance->group();
+		if (group.isEmpty())
+			continue;
+
+		// keep a list/set of groups for choosing
+		m_groups.insert(group);
+
+		if (!groupMap.count(group))
+		{
+			QSet<QString> set;
+			set.insert(id);
+			groupMap[group] = set;
+		}
+		else
+		{
+			QSet<QString> &set = groupMap[group];
+			set.insert(id);
+		}
+	}
+	QJsonObject toplevel;
+	toplevel.insert("formatVersion", QJsonValue(QString("1")));
+	QJsonObject groupsArr;
+	for (auto iter = groupMap.begin(); iter != groupMap.end(); iter++)
+	{
+		auto list = iter.value();
+		auto name = iter.key();
+		QJsonObject groupObj;
+		QJsonArray instanceArr;
+		groupObj.insert("hidden", QJsonValue(QString("false")));
+		for (auto item : list)
+		{
+			instanceArr.append(QJsonValue(item));
+		}
+		groupObj.insert("instances", instanceArr);
+		groupsArr.insert(name, groupObj);
+	}
+	toplevel.insert("groups", groupsArr);
+	QJsonDocument doc(toplevel);
+	try
+	{
+		FS::write(groupFileName, doc.toJson());
+	}
+	catch(FS::FileSystemException & e)
+	{
+		qCritical() << "Failed to write instance group file :" << e.cause();
+	}
+}
+
+void InstanceList::loadGroupList(QMap<QString, QString> &groupMap)
+{
+	QString groupFileName = m_instDir + "/instgroups.json";
+
+	// if there's no group file, fail
+	if (!QFileInfo(groupFileName).exists())
+		return;
+
+	QByteArray jsonData;
+	try
+	{
+		jsonData = FS::read(groupFileName);
+	}
+	catch (FS::FileSystemException & e)
+	{
+		qCritical() << "Failed to read instance group file :" << e.cause();
+		return;
+	}
+
+	QJsonParseError error;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &error);
+
+	// if the json was bad, fail
+	if (error.error != QJsonParseError::NoError)
+	{
+		qCritical() << QString("Failed to parse instance group file: %1 at offset %2")
+							.arg(error.errorString(), QString::number(error.offset))
+							.toUtf8();
+		return;
+	}
+
+	// if the root of the json wasn't an object, fail
+	if (!jsonDoc.isObject())
+	{
+		qWarning() << "Invalid group file. Root entry should be an object.";
+		return;
+	}
+
+	QJsonObject rootObj = jsonDoc.object();
+
+	// Make sure the format version matches, otherwise fail.
+	if (rootObj.value("formatVersion").toVariant().toInt() != GROUP_FILE_FORMAT_VERSION)
+		return;
+
+	// Get the groups. if it's not an object, fail
+	if (!rootObj.value("groups").isObject())
+	{
+		qWarning() << "Invalid group list JSON: 'groups' should be an object.";
+		return;
+	}
+
+	// Iterate through all the groups.
+	QJsonObject groupMapping = rootObj.value("groups").toObject();
+	for (QJsonObject::iterator iter = groupMapping.begin(); iter != groupMapping.end(); iter++)
+	{
+		QString groupName = iter.key();
+
+		// If not an object, complain and skip to the next one.
+		if (!iter.value().isObject())
+		{
+			qWarning() << QString("Group '%1' in the group list should "
+								   "be an object.")
+							   .arg(groupName)
+							   .toUtf8();
+			continue;
+		}
+
+		QJsonObject groupObj = iter.value().toObject();
+		if (!groupObj.value("instances").isArray())
+		{
+			qWarning() << QString("Group '%1' in the group list is invalid. "
+								   "It should contain an array "
+								   "called 'instances'.")
+							   .arg(groupName)
+							   .toUtf8();
+			continue;
+		}
+
+		// keep a list/set of groups for choosing
+		m_groups.insert(groupName);
+
+		// Iterate through the list of instances in the group.
+		QJsonArray instancesArray = groupObj.value("instances").toArray();
+
+		for (QJsonArray::iterator iter2 = instancesArray.begin(); iter2 != instancesArray.end();
+			 iter2++)
+		{
+			groupMap[(*iter2).toString()] = groupName;
+		}
+	}
+}
+
+InstanceList::InstListError InstanceList::loadList()
+{
+	// load the instance groups
+	QMap<QString, QString> groupMap;
+	loadGroupList(groupMap);
+
+	QList<InstancePtr> tempList;
+	{
+		QDirIterator iter(m_instDir, QDir::Dirs | QDir::NoDot | QDir::NoDotDot | QDir::Readable,
+						  QDirIterator::FollowSymlinks);
+		while (iter.hasNext())
+		{
+			QString subDir = iter.next();
+			if (!QFileInfo(FS::PathCombine(subDir, "instance.cfg")).exists())
+				continue;
+			qDebug() << "Loading MultiMC instance from " << subDir;
+			InstancePtr instPtr;
+			auto error = loadInstance(instPtr, subDir);
+			if(!continueProcessInstance(instPtr, error, subDir, groupMap))
+				continue;
+			tempList.append(instPtr);
+		}
+	}
+
+	// FIXME: generalize
+	FTBPlugin::loadInstances(m_globalSettings, groupMap, tempList);
+
+	beginResetModel();
+	m_instances.clear();
+	for(auto inst: tempList)
+	{
+		inst->setParent(this);
+		connect(inst.get(), SIGNAL(propertiesChanged(BaseInstance *)), this,
+				SLOT(propertiesChanged(BaseInstance *)));
+		connect(inst.get(), SIGNAL(groupChanged()), this, SLOT(groupChanged()));
+		connect(inst.get(), SIGNAL(nuked(BaseInstance *)), this,
+				SLOT(instanceNuked(BaseInstance *)));
+		m_instances.append(inst);
+	}
+	endResetModel();
+	emit dataIsInvalid();
+	return NoError;
+}
+
+/// Clear all instances. Triggers notifications.
+void InstanceList::clear()
+{
+	beginResetModel();
+	saveGroupList();
+	m_instances.clear();
+	endResetModel();
+	emit dataIsInvalid();
+}
+
+void InstanceList::on_InstFolderChanged(const Setting &setting, QVariant value)
+{
+	m_instDir = value.toString();
+	loadList();
+}
+
+/// Add an instance. Triggers notifications, returns the new index
+int InstanceList::add(InstancePtr t)
+{
+	beginInsertRows(QModelIndex(), m_instances.size(), m_instances.size());
+	m_instances.append(t);
+	t->setParent(this);
+	connect(t.get(), SIGNAL(propertiesChanged(BaseInstance *)), this,
+			SLOT(propertiesChanged(BaseInstance *)));
+	connect(t.get(), SIGNAL(groupChanged()), this, SLOT(groupChanged()));
+	connect(t.get(), SIGNAL(nuked(BaseInstance *)), this, SLOT(instanceNuked(BaseInstance *)));
+	endInsertRows();
+	return count() - 1;
+}
+
+InstancePtr InstanceList::getInstanceById(QString instId) const
+{
+	if(instId.isEmpty())
+		return InstancePtr();
+	for(auto & inst: m_instances)
+	{
+		if (inst->id() == instId)
+		{
+			return inst;
+		}
+	}
+	return InstancePtr();
+}
+
+QModelIndex InstanceList::getInstanceIndexById(const QString &id) const
+{
+	return index(getInstIndex(getInstanceById(id).get()));
+}
+
+int InstanceList::getInstIndex(BaseInstance *inst) const
+{
+	int count = m_instances.count();
+	for (int i = 0; i < count; i++)
+	{
+		if (inst == m_instances[i].get())
+		{
+			return i;
+		}
+	}
+	return -1;
+}
+
+bool InstanceList::continueProcessInstance(InstancePtr instPtr, const int error,
+										   const QDir &dir, QMap<QString, QString> &groupMap)
+{
+	if (error != InstanceList::NoLoadError && error != InstanceList::NotAnInstance)
+	{
+		QString errorMsg = QString("Failed to load instance %1: ")
+							   .arg(QFileInfo(dir.absolutePath()).baseName())
+							   .toUtf8();
+
+		switch (error)
+		{
+		default:
+			errorMsg += QString("Unknown instance loader error %1").arg(error);
+			break;
+		}
+		qCritical() << errorMsg.toUtf8();
+		return false;
+	}
+	else if (!instPtr)
+	{
+		qCritical() << QString("Error loading instance %1. Instance loader returned null.")
+							.arg(QFileInfo(dir.absolutePath()).baseName())
+							.toUtf8();
+		return false;
+	}
+	else
+	{
+		auto iter = groupMap.find(instPtr->id());
+		if (iter != groupMap.end())
+		{
+			instPtr->setGroupInitial((*iter));
+		}
+		qDebug() << "Loaded instance " << instPtr->name() << " from " << dir.absolutePath();
+		return true;
+	}
+}
+
+InstanceList::InstLoadError
+InstanceList::loadInstance(InstancePtr &inst, const QString &instDir)
+{
+	auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(instDir, "instance.cfg"));
+
+	instanceSettings->registerSetting("InstanceType", "Legacy");
+
+	QString inst_type = instanceSettings->get("InstanceType").toString();
+
+	// FIXME: replace with a map lookup, where instance classes register their types
+	if (inst_type == "OneSix" || inst_type == "Nostalgia")
+	{
+		inst.reset(new OneSixInstance(m_globalSettings, instanceSettings, instDir));
+	}
+	else if (inst_type == "Legacy")
+	{
+		inst.reset(new LegacyInstance(m_globalSettings, instanceSettings, instDir));
+	}
+	else
+	{
+		inst.reset(new NullInstance(m_globalSettings, instanceSettings, instDir));
+	}
+	inst->init();
+	return NoLoadError;
+}
+
+InstanceList::InstCreateError
+InstanceList::createInstance(InstancePtr &inst, BaseVersionPtr version, const QString &instDir)
+{
+	QDir rootDir(instDir);
+
+	qDebug() << instDir.toUtf8();
+	if (!rootDir.exists() && !rootDir.mkpath("."))
+	{
+		qCritical() << "Can't create instance folder" << instDir;
+		return InstanceList::CantCreateDir;
+	}
+
+	if (!version)
+	{
+		qCritical() << "Can't create instance for non-existing MC version";
+		return InstanceList::NoSuchVersion;
+	}
+
+	auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(instDir, "instance.cfg"));
+	instanceSettings->registerSetting("InstanceType", "Legacy");
+
+	auto minecraftVersion = std::dynamic_pointer_cast<MinecraftVersion>(version);
+	if(minecraftVersion)
+	{
+		auto mcVer = std::dynamic_pointer_cast<MinecraftVersion>(version);
+		instanceSettings->set("InstanceType", "OneSix");
+		inst.reset(new OneSixInstance(m_globalSettings, instanceSettings, instDir));
+		inst->setIntendedVersionId(version->descriptor());
+		inst->init();
+		return InstanceList::NoCreateError;
+	}
+	return InstanceList::NoSuchVersion;
+}
+
+InstanceList::InstCreateError
+InstanceList::copyInstance(InstancePtr &newInstance, InstancePtr &oldInstance, const QString &instDir, bool copySaves)
+{
+	QDir rootDir(instDir);
+	std::unique_ptr<IPathMatcher> matcher;
+	if(!copySaves)
+	{
+		auto matcherReal = new RegexpMatcher("[.]?minecraft/saves");
+		matcherReal->caseSensitive(false);
+		matcher.reset(matcherReal);
+	}
+
+	qDebug() << instDir.toUtf8();
+	FS::copy folderCopy(oldInstance->instanceRoot(), instDir);
+	folderCopy.followSymlinks(false).blacklist(matcher.get());
+	if (!folderCopy())
+	{
+		FS::deletePath(instDir);
+		return InstanceList::CantCreateDir;
+	}
+
+	INISettingsObject settings_obj(FS::PathCombine(instDir, "instance.cfg"));
+	settings_obj.registerSetting("InstanceType", "Legacy");
+	QString inst_type = settings_obj.get("InstanceType").toString();
+
+	oldInstance->copy(instDir);
+
+	auto error = loadInstance(newInstance, instDir);
+
+	switch (error)
+	{
+	case NoLoadError:
+		return NoCreateError;
+	case NotAnInstance:
+		rootDir.removeRecursively();
+		return CantCreateDir;
+	default:
+	case UnknownLoadError:
+		rootDir.removeRecursively();
+		return UnknownCreateError;
+	}
+}
+
+void InstanceList::instanceNuked(BaseInstance *inst)
+{
+	int i = getInstIndex(inst);
+	if (i != -1)
+	{
+		beginRemoveRows(QModelIndex(), i, i);
+		m_instances.removeAt(i);
+		endRemoveRows();
+	}
+}
+
+void InstanceList::propertiesChanged(BaseInstance *inst)
+{
+	int i = getInstIndex(inst);
+	if (i != -1)
+	{
+		emit dataChanged(index(i), index(i));
+	}
+}
diff --git a/libraries/logic/InstanceList.h b/libraries/logic/InstanceList.h
new file mode 100644
index 00000000..074cca7c
--- /dev/null
+++ b/libraries/logic/InstanceList.h
@@ -0,0 +1,187 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QAbstractListModel>
+#include <QSet>
+
+#include "BaseInstance.h"
+
+#include "multimc_logic_export.h"
+
+class BaseInstance;
+class QDir;
+
+class MULTIMC_LOGIC_EXPORT InstanceList : public QAbstractListModel
+{
+	Q_OBJECT
+private:
+	void loadGroupList(QMap<QString, QString> &groupList);
+	void suspendGroupSaving();
+	void resumeGroupSaving();
+
+public slots:
+	void saveGroupList();
+
+public:
+	explicit InstanceList(SettingsObjectPtr globalSettings, const QString &instDir, QObject *parent = 0);
+	virtual ~InstanceList();
+
+public:
+	QModelIndex index(int row, int column = 0, const QModelIndex &parent = QModelIndex()) const;
+	int rowCount(const QModelIndex &parent = QModelIndex()) const;
+	QVariant data(const QModelIndex &index, int role) const;
+	Qt::ItemFlags flags(const QModelIndex &index) const;
+
+	enum AdditionalRoles
+	{
+		GroupRole = Qt::UserRole,
+		InstancePointerRole = 0x34B1CB48, ///< Return pointer to real instance
+		InstanceIDRole = 0x34B1CB49 ///< Return id if the instance
+	};
+	/*!
+	 * \brief Error codes returned by functions in the InstanceList class.
+	 * NoError Indicates that no error occurred.
+	 * UnknownError indicates that an unspecified error occurred.
+	 */
+	enum InstListError
+	{
+		NoError = 0,
+		UnknownError
+	};
+
+	enum InstLoadError
+	{
+		NoLoadError = 0,
+		UnknownLoadError,
+		NotAnInstance
+	};
+
+	enum InstCreateError
+	{
+		NoCreateError = 0,
+		NoSuchVersion,
+		UnknownCreateError,
+		InstExists,
+		CantCreateDir
+	};
+
+	QString instDir() const
+	{
+		return m_instDir;
+	}
+
+	/*!
+	 * \brief Get the instance at index
+	 */
+	InstancePtr at(int i) const
+	{
+		return m_instances.at(i);
+	}
+	;
+
+	/*!
+	 * \brief Get the count of loaded instances
+	 */
+	int count() const
+	{
+		return m_instances.count();
+	}
+	;
+
+	/// Clear all instances. Triggers notifications.
+	void clear();
+
+	/// Add an instance. Triggers notifications, returns the new index
+	int add(InstancePtr t);
+
+	/// Get an instance by ID
+	InstancePtr getInstanceById(QString id) const;
+
+	QModelIndex getInstanceIndexById(const QString &id) const;
+
+	// FIXME: instead of iterating through all instances and forming a set, keep the set around
+	QStringList getGroups();
+
+	void deleteGroup(const QString & name);
+
+	/*!
+	 * \brief Creates a stub instance
+	 *
+	 * \param inst Pointer to store the created instance in.
+	 * \param version Game version to use for the instance
+	 * \param instDir The new instance's directory.
+	 * \return An InstCreateError error code.
+	 * - InstExists if the given instance directory is already an instance.
+	 * - CantCreateDir if the given instance directory cannot be created.
+	 */
+	InstCreateError createInstance(InstancePtr &inst, BaseVersionPtr version,
+								   const QString &instDir);
+
+	/*!
+	 * \brief Creates a copy of an existing instance with a new name
+	 *
+	 * \param newInstance Pointer to store the created instance in.
+	 * \param oldInstance The instance to copy
+	 * \param instDir The new instance's directory.
+	 * \return An InstCreateError error code.
+	 * - InstExists if the given instance directory is already an instance.
+	 * - CantCreateDir if the given instance directory cannot be created.
+	 */
+	InstCreateError copyInstance(InstancePtr &newInstance, InstancePtr &oldInstance,
+								 const QString &instDir, bool copySaves);
+
+	/*!
+	 * \brief Loads an instance from the given directory.
+	 * Checks the instance's INI file to figure out what the instance's type is first.
+	 * \param inst Pointer to store the loaded instance in.
+	 * \param instDir The instance's directory.
+	 * \return An InstLoadError error code.
+	 * - NotAnInstance if the given instance directory isn't a valid instance.
+	 */
+	InstLoadError loadInstance(InstancePtr &inst, const QString &instDir);
+
+signals:
+	void dataIsInvalid();
+
+public slots:
+	void on_InstFolderChanged(const Setting &setting, QVariant value);
+
+	/*!
+	 * \brief Loads the instance list. Triggers notifications.
+	 */
+	InstListError loadList();
+
+private slots:
+	void propertiesChanged(BaseInstance *inst);
+	void instanceNuked(BaseInstance *inst);
+	void groupChanged();
+
+private:
+	int getInstIndex(BaseInstance *inst) const;
+
+public:
+	static bool continueProcessInstance(InstancePtr instPtr, const int error, const QDir &dir, QMap<QString, QString> &groupMap);
+
+protected:
+	QString m_instDir;
+	QList<InstancePtr> m_instances;
+	QSet<QString> m_groups;
+	SettingsObjectPtr m_globalSettings;
+	bool suspendedGroupSave = false;
+	bool queuedGroupSave = false;
+};
diff --git a/libraries/logic/Json.cpp b/libraries/logic/Json.cpp
new file mode 100644
index 00000000..f2cbc8a3
--- /dev/null
+++ b/libraries/logic/Json.cpp
@@ -0,0 +1,272 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "Json.h"
+
+#include <QFile>
+
+#include "FileSystem.h"
+#include <math.h>
+
+namespace Json
+{
+void write(const QJsonDocument &doc, const QString &filename)
+{
+	FS::write(filename, doc.toJson());
+}
+void write(const QJsonObject &object, const QString &filename)
+{
+	write(QJsonDocument(object), filename);
+}
+void write(const QJsonArray &array, const QString &filename)
+{
+	write(QJsonDocument(array), filename);
+}
+
+QByteArray toBinary(const QJsonObject &obj)
+{
+	return QJsonDocument(obj).toBinaryData();
+}
+QByteArray toBinary(const QJsonArray &array)
+{
+	return QJsonDocument(array).toBinaryData();
+}
+QByteArray toText(const QJsonObject &obj)
+{
+	return QJsonDocument(obj).toJson(QJsonDocument::Compact);
+}
+QByteArray toText(const QJsonArray &array)
+{
+	return QJsonDocument(array).toJson(QJsonDocument::Compact);
+}
+
+static bool isBinaryJson(const QByteArray &data)
+{
+	decltype(QJsonDocument::BinaryFormatTag) tag = QJsonDocument::BinaryFormatTag;
+	return memcmp(data.constData(), &tag, sizeof(QJsonDocument::BinaryFormatTag)) == 0;
+}
+QJsonDocument requireDocument(const QByteArray &data, const QString &what)
+{
+	if (isBinaryJson(data))
+	{
+		QJsonDocument doc = QJsonDocument::fromBinaryData(data);
+		if (doc.isNull())
+		{
+			throw JsonException(what + ": Invalid JSON (binary JSON detected)");
+		}
+		return doc;
+	}
+	else
+	{
+		QJsonParseError error;
+		QJsonDocument doc = QJsonDocument::fromJson(data, &error);
+		if (error.error != QJsonParseError::NoError)
+		{
+			throw JsonException(what + ": Error parsing JSON: " + error.errorString());
+		}
+		return doc;
+	}
+}
+QJsonDocument requireDocument(const QString &filename, const QString &what)
+{
+	return requireDocument(FS::read(filename), what);
+}
+QJsonObject requireObject(const QJsonDocument &doc, const QString &what)
+{
+	if (!doc.isObject())
+	{
+		throw JsonException(what + " is not an object");
+	}
+	return doc.object();
+}
+QJsonArray requireArray(const QJsonDocument &doc, const QString &what)
+{
+	if (!doc.isArray())
+	{
+		throw JsonException(what + " is not an array");
+	}
+	return doc.array();
+}
+
+void writeString(QJsonObject &to, const QString &key, const QString &value)
+{
+	if (!value.isEmpty())
+	{
+		to.insert(key, value);
+	}
+}
+
+void writeStringList(QJsonObject &to, const QString &key, const QStringList &values)
+{
+	if (!values.isEmpty())
+	{
+		QJsonArray array;
+		for(auto value: values)
+		{
+			array.append(value);
+		}
+		to.insert(key, array);
+	}
+}
+
+template<>
+QJsonValue toJson<QUrl>(const QUrl &url)
+{
+	return QJsonValue(url.toString(QUrl::FullyEncoded));
+}
+template<>
+QJsonValue toJson<QByteArray>(const QByteArray &data)
+{
+	return QJsonValue(QString::fromLatin1(data.toHex()));
+}
+template<>
+QJsonValue toJson<QDateTime>(const QDateTime &datetime)
+{
+	return QJsonValue(datetime.toString(Qt::ISODate));
+}
+template<>
+QJsonValue toJson<QDir>(const QDir &dir)
+{
+	return QDir::current().relativeFilePath(dir.absolutePath());
+}
+template<>
+QJsonValue toJson<QUuid>(const QUuid &uuid)
+{
+	return uuid.toString();
+}
+template<>
+QJsonValue toJson<QVariant>(const QVariant &variant)
+{
+	return QJsonValue::fromVariant(variant);
+}
+
+
+template<> QByteArray requireIsType<QByteArray>(const QJsonValue &value, const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, what);
+	// ensure that the string can be safely cast to Latin1
+	if (string != QString::fromLatin1(string.toLatin1()))
+	{
+		throw JsonException(what + " is not encodable as Latin1");
+	}
+	return QByteArray::fromHex(string.toLatin1());
+}
+
+template<> QJsonArray requireIsType<QJsonArray>(const QJsonValue &value, const QString &what)
+{
+	if (!value.isArray())
+	{
+		throw JsonException(what + " is not an array");
+	}
+	return value.toArray();
+}
+
+
+template<> QString requireIsType<QString>(const QJsonValue &value, const QString &what)
+{
+	if (!value.isString())
+	{
+		throw JsonException(what + " is not a string");
+	}
+	return value.toString();
+}
+
+template<> bool requireIsType<bool>(const QJsonValue &value, const QString &what)
+{
+	if (!value.isBool())
+	{
+		throw JsonException(what + " is not a bool");
+	}
+	return value.toBool();
+}
+
+template<> double requireIsType<double>(const QJsonValue &value, const QString &what)
+{
+	if (!value.isDouble())
+	{
+		throw JsonException(what + " is not a double");
+	}
+	return value.toDouble();
+}
+
+template<> int requireIsType<int>(const QJsonValue &value, const QString &what)
+{
+	const double doubl = requireIsType<double>(value, what);
+	if (fmod(doubl, 1) != 0)
+	{
+		throw JsonException(what + " is not an integer");
+	}
+	return int(doubl);
+}
+
+template<> QDateTime requireIsType<QDateTime>(const QJsonValue &value, const QString &what)
+{
+	const QString string = requireIsType<QString>(value, what);
+	const QDateTime datetime = QDateTime::fromString(string, Qt::ISODate);
+	if (!datetime.isValid())
+	{
+		throw JsonException(what + " is not a ISO formatted date/time value");
+	}
+	return datetime;
+}
+
+template<> QUrl requireIsType<QUrl>(const QJsonValue &value, const QString &what)
+{
+	const QString string = ensureIsType<QString>(value, what);
+	if (string.isEmpty())
+	{
+		return QUrl();
+	}
+	const QUrl url = QUrl(string, QUrl::StrictMode);
+	if (!url.isValid())
+	{
+		throw JsonException(what + " is not a correctly formatted URL");
+	}
+	return url;
+}
+
+template<> QDir requireIsType<QDir>(const QJsonValue &value, const QString &what)
+{
+	const QString string = requireIsType<QString>(value, what);
+	// FIXME: does not handle invalid characters!
+	return QDir::current().absoluteFilePath(string);
+}
+
+template<> QUuid requireIsType<QUuid>(const QJsonValue &value, const QString &what)
+{
+	const QString string = requireIsType<QString>(value, what);
+	const QUuid uuid = QUuid(string);
+	if (uuid.toString() != string) // converts back => valid
+	{
+		throw JsonException(what + " is not a valid UUID");
+	}
+	return uuid;
+}
+
+template<> QJsonObject requireIsType<QJsonObject>(const QJsonValue &value, const QString &what)
+{
+	if (!value.isObject())
+	{
+		throw JsonException(what + " is not an object");
+	}
+	return value.toObject();
+}
+
+template<> QVariant requireIsType<QVariant>(const QJsonValue &value, const QString &what)
+{
+	if (value.isNull() || value.isUndefined())
+	{
+		throw JsonException(what + " is null or undefined");
+	}
+	return value.toVariant();
+}
+
+template<> QJsonValue requireIsType<QJsonValue>(const QJsonValue &value, const QString &what)
+{
+	if (value.isNull() || value.isUndefined())
+	{
+		throw JsonException(what + " is null or undefined");
+	}
+	return value;
+}
+
+}
diff --git a/libraries/logic/Json.h b/libraries/logic/Json.h
new file mode 100644
index 00000000..2cb60f0e
--- /dev/null
+++ b/libraries/logic/Json.h
@@ -0,0 +1,249 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QJsonObject>
+#include <QDateTime>
+#include <QUrl>
+#include <QDir>
+#include <QUuid>
+#include <QVariant>
+#include <memory>
+
+#include "Exception.h"
+
+namespace Json
+{
+class MULTIMC_LOGIC_EXPORT JsonException : public ::Exception
+{
+public:
+	JsonException(const QString &message) : Exception(message) {}
+};
+
+/// @throw FileSystemException
+void write(const QJsonDocument &doc, const QString &filename);
+/// @throw FileSystemException
+void write(const QJsonObject &object, const QString &filename);
+/// @throw FileSystemException
+void write(const QJsonArray &array, const QString &filename);
+
+QByteArray toBinary(const QJsonObject &obj);
+QByteArray toBinary(const QJsonArray &array);
+QByteArray toText(const QJsonObject &obj);
+QByteArray toText(const QJsonArray &array);
+
+/// @throw JsonException
+MULTIMC_LOGIC_EXPORT QJsonDocument requireDocument(const QByteArray &data, const QString &what = "Document");
+/// @throw JsonException
+MULTIMC_LOGIC_EXPORT QJsonDocument requireDocument(const QString &filename, const QString &what = "Document");
+/// @throw JsonException
+MULTIMC_LOGIC_EXPORT QJsonObject requireObject(const QJsonDocument &doc, const QString &what = "Document");
+/// @throw JsonException
+MULTIMC_LOGIC_EXPORT QJsonArray requireArray(const QJsonDocument &doc, const QString &what = "Document");
+
+/////////////////// WRITING ////////////////////
+
+void writeString(QJsonObject & to, const QString &key, const QString &value);
+void writeStringList(QJsonObject & to, const QString &key, const QStringList &values);
+
+template<typename T>
+QJsonValue toJson(const T &t)
+{
+	return QJsonValue(t);
+}
+template<>
+QJsonValue toJson<QUrl>(const QUrl &url);
+template<>
+QJsonValue toJson<QByteArray>(const QByteArray &data);
+template<>
+QJsonValue toJson<QDateTime>(const QDateTime &datetime);
+template<>
+QJsonValue toJson<QDir>(const QDir &dir);
+template<>
+QJsonValue toJson<QUuid>(const QUuid &uuid);
+template<>
+QJsonValue toJson<QVariant>(const QVariant &variant);
+
+template<typename T>
+QJsonArray toJsonArray(const QList<T> &container)
+{
+	QJsonArray array;
+	for (const T item : container)
+	{
+		array.append(toJson<T>(item));
+	}
+	return array;
+}
+
+////////////////// READING ////////////////////
+
+/// @throw JsonException
+template <typename T>
+T requireIsType(const QJsonValue &value, const QString &what = "Value");
+
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT double requireIsType<double>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT bool requireIsType<bool>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT int requireIsType<int>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QJsonObject requireIsType<QJsonObject>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QJsonArray requireIsType<QJsonArray>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QJsonValue requireIsType<QJsonValue>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QByteArray requireIsType<QByteArray>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QDateTime requireIsType<QDateTime>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QVariant requireIsType<QVariant>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QString requireIsType<QString>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QUuid requireIsType<QUuid>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QDir requireIsType<QDir>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> MULTIMC_LOGIC_EXPORT QUrl requireIsType<QUrl>(const QJsonValue &value, const QString &what);
+
+// the following functions are higher level functions, that make use of the above functions for
+// type conversion
+template <typename T>
+T ensureIsType(const QJsonValue &value, const T default_ = T(), const QString &what = "Value")
+{
+	if (value.isUndefined() || value.isNull())
+	{
+		return default_;
+	}
+	try
+	{
+		return requireIsType<T>(value, what);
+	}
+	catch (JsonException &)
+	{
+		return default_;
+	}
+}
+
+/// @throw JsonException
+template <typename T>
+T requireIsType(const QJsonObject &parent, const QString &key, const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		throw JsonException(localWhat + "s parent does not contain " + localWhat);
+	}
+	return requireIsType<T>(parent.value(key), localWhat);
+}
+
+template <typename T>
+T ensureIsType(const QJsonObject &parent, const QString &key, const T default_ = T(), const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		return default_;
+	}
+	return ensureIsType<T>(parent.value(key), default_, localWhat);
+}
+
+template <typename T>
+QVector<T> requireIsArrayOf(const QJsonDocument &doc)
+{
+	const QJsonArray array = requireArray(doc);
+	QVector<T> out;
+	for (const QJsonValue val : array)
+	{
+		out.append(requireIsType<T>(val, "Document"));
+	}
+	return out;
+}
+
+template <typename T>
+QVector<T> ensureIsArrayOf(const QJsonValue &value, const QString &what = "Value")
+{
+	const QJsonArray array = ensureIsType<QJsonArray>(value, QJsonArray(), what);
+	QVector<T> out;
+	for (const QJsonValue val : array)
+	{
+		out.append(requireIsType<T>(val, what));
+	}
+	return out;
+}
+
+template <typename T>
+QVector<T> ensureIsArrayOf(const QJsonValue &value, const QVector<T> default_, const QString &what = "Value")
+{
+	if (value.isUndefined())
+	{
+		return default_;
+	}
+	return ensureIsArrayOf<T>(value, what);
+}
+
+/// @throw JsonException
+template <typename T>
+QVector<T> requireIsArrayOf(const QJsonObject &parent, const QString &key, const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		throw JsonException(localWhat + "s parent does not contain " + localWhat);
+	}
+	return ensureIsArrayOf<T>(parent.value(key), localWhat);
+}
+
+template <typename T>
+QVector<T> ensureIsArrayOf(const QJsonObject &parent, const QString &key,
+						 const QVector<T> &default_ = QVector<T>(), const QString &what = "__placeholder__")
+{
+	const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+	if (!parent.contains(key))
+	{
+		return default_;
+	}
+	return ensureIsArrayOf<T>(parent.value(key), default_, localWhat);
+}
+
+// this macro part could be replaced by variadic functions that just pass on their arguments, but that wouldn't work well with IDE helpers
+#define JSON_HELPERFUNCTIONS(NAME, TYPE) \
+	inline TYPE require##NAME(const QJsonValue &value, const QString &what = "Value") \
+	{ \
+		return requireIsType<TYPE>(value, what); \
+	} \
+	inline TYPE ensure##NAME(const QJsonValue &value, const TYPE default_ = TYPE(), const QString &what = "Value") \
+	{ \
+		return ensureIsType<TYPE>(value, default_, what); \
+	} \
+	inline TYPE require##NAME(const QJsonObject &parent, const QString &key, const QString &what = "__placeholder__") \
+	{ \
+		return requireIsType<TYPE>(parent, key, what); \
+	} \
+	inline TYPE ensure##NAME(const QJsonObject &parent, const QString &key, const TYPE default_ = TYPE(), const QString &what = "__placeholder") \
+	{ \
+		return ensureIsType<TYPE>(parent, key, default_, what); \
+	}
+
+JSON_HELPERFUNCTIONS(Array, QJsonArray)
+JSON_HELPERFUNCTIONS(Object, QJsonObject)
+JSON_HELPERFUNCTIONS(JsonValue, QJsonValue)
+JSON_HELPERFUNCTIONS(String, QString)
+JSON_HELPERFUNCTIONS(Boolean, bool)
+JSON_HELPERFUNCTIONS(Double, double)
+JSON_HELPERFUNCTIONS(Integer, int)
+JSON_HELPERFUNCTIONS(DateTime, QDateTime)
+JSON_HELPERFUNCTIONS(Url, QUrl)
+JSON_HELPERFUNCTIONS(ByteArray, QByteArray)
+JSON_HELPERFUNCTIONS(Dir, QDir)
+JSON_HELPERFUNCTIONS(Uuid, QUuid)
+JSON_HELPERFUNCTIONS(Variant, QVariant)
+
+#undef JSON_HELPERFUNCTIONS
+
+}
+using JSONValidationError = Json::JsonException;
diff --git a/libraries/logic/MMCStrings.cpp b/libraries/logic/MMCStrings.cpp
new file mode 100644
index 00000000..c50d596e
--- /dev/null
+++ b/libraries/logic/MMCStrings.cpp
@@ -0,0 +1,76 @@
+#include "MMCStrings.h"
+
+/// TAKEN FROM Qt, because it doesn't expose it intelligently
+static inline QChar getNextChar(const QString &s, int location)
+{
+	return (location < s.length()) ? s.at(location) : QChar();
+}
+
+/// TAKEN FROM Qt, because it doesn't expose it intelligently
+int Strings::naturalCompare(const QString &s1, const QString &s2, Qt::CaseSensitivity cs)
+{
+	for (int l1 = 0, l2 = 0; l1 <= s1.count() && l2 <= s2.count(); ++l1, ++l2)
+	{
+		// skip spaces, tabs and 0's
+		QChar c1 = getNextChar(s1, l1);
+		while (c1.isSpace())
+			c1 = getNextChar(s1, ++l1);
+		QChar c2 = getNextChar(s2, l2);
+		while (c2.isSpace())
+			c2 = getNextChar(s2, ++l2);
+
+		if (c1.isDigit() && c2.isDigit())
+		{
+			while (c1.digitValue() == 0)
+				c1 = getNextChar(s1, ++l1);
+			while (c2.digitValue() == 0)
+				c2 = getNextChar(s2, ++l2);
+
+			int lookAheadLocation1 = l1;
+			int lookAheadLocation2 = l2;
+			int currentReturnValue = 0;
+			// find the last digit, setting currentReturnValue as we go if it isn't equal
+			for (QChar lookAhead1 = c1, lookAhead2 = c2;
+				 (lookAheadLocation1 <= s1.length() && lookAheadLocation2 <= s2.length());
+				 lookAhead1 = getNextChar(s1, ++lookAheadLocation1),
+					   lookAhead2 = getNextChar(s2, ++lookAheadLocation2))
+			{
+				bool is1ADigit = !lookAhead1.isNull() && lookAhead1.isDigit();
+				bool is2ADigit = !lookAhead2.isNull() && lookAhead2.isDigit();
+				if (!is1ADigit && !is2ADigit)
+					break;
+				if (!is1ADigit)
+					return -1;
+				if (!is2ADigit)
+					return 1;
+				if (currentReturnValue == 0)
+				{
+					if (lookAhead1 < lookAhead2)
+					{
+						currentReturnValue = -1;
+					}
+					else if (lookAhead1 > lookAhead2)
+					{
+						currentReturnValue = 1;
+					}
+				}
+			}
+			if (currentReturnValue != 0)
+				return currentReturnValue;
+		}
+		if (cs == Qt::CaseInsensitive)
+		{
+			if (!c1.isLower())
+				c1 = c1.toLower();
+			if (!c2.isLower())
+				c2 = c2.toLower();
+		}
+		int r = QString::localeAwareCompare(c1, c2);
+		if (r < 0)
+			return -1;
+		if (r > 0)
+			return 1;
+	}
+	// The two strings are the same (02 == 2) so fall back to the normal sort
+	return QString::compare(s1, s2, cs);
+}
diff --git a/libraries/logic/MMCStrings.h b/libraries/logic/MMCStrings.h
new file mode 100644
index 00000000..5606b909
--- /dev/null
+++ b/libraries/logic/MMCStrings.h
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <QString>
+
+#include "multimc_logic_export.h"
+
+namespace Strings
+{
+	int MULTIMC_LOGIC_EXPORT naturalCompare(const QString &s1, const QString &s2, Qt::CaseSensitivity cs);
+}
diff --git a/libraries/logic/MMCZip.cpp b/libraries/logic/MMCZip.cpp
new file mode 100644
index 00000000..0f35bc70
--- /dev/null
+++ b/libraries/logic/MMCZip.cpp
@@ -0,0 +1,491 @@
+/*
+Copyright (C) 2010 Roberto Pompermaier
+Copyright (C) 2005-2014 Sergey A. Tachenov
+
+Parts of this file were part of QuaZIP.
+
+QuaZIP is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation, either version 2.1 of the License, or
+(at your option) any later version.
+
+QuaZIP is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with QuaZIP.  If not, see <http://www.gnu.org/licenses/>.
+
+See COPYING file for the full LGPL text.
+
+Original ZIP package is copyrighted by Gilles Vollant and contributors,
+see quazip/(un)MMCZip.h files for details. Basically it's the zlib license.
+*/
+
+#include <quazip.h>
+#include <JlCompress.h>
+#include <quazipdir.h>
+#include "MMCZip.h"
+#include "FileSystem.h"
+
+#include <QDebug>
+
+bool copyData(QIODevice &inFile, QIODevice &outFile)
+{
+	while (!inFile.atEnd())
+	{
+		char buf[4096];
+		qint64 readLen = inFile.read(buf, 4096);
+		if (readLen <= 0)
+			return false;
+		if (outFile.write(buf, readLen) != readLen)
+			return false;
+	}
+	return true;
+}
+
+QStringList MMCZip::extractDir(QString fileCompressed, QString dir)
+{
+	return JlCompress::extractDir(fileCompressed, dir);
+}
+
+bool compressFile(QuaZip *zip, QString fileName, QString fileDest)
+{
+	if (!zip)
+	{
+		return false;
+	}
+	if (zip->getMode() != QuaZip::mdCreate && zip->getMode() != QuaZip::mdAppend &&
+		zip->getMode() != QuaZip::mdAdd)
+	{
+		return false;
+	}
+
+	QFile inFile;
+	inFile.setFileName(fileName);
+	if (!inFile.open(QIODevice::ReadOnly))
+	{
+		return false;
+	}
+
+	QuaZipFile outFile(zip);
+	if (!outFile.open(QIODevice::WriteOnly, QuaZipNewInfo(fileDest, inFile.fileName())))
+	{
+		return false;
+	}
+
+	if (!copyData(inFile, outFile) || outFile.getZipError() != UNZ_OK)
+	{
+		return false;
+	}
+
+	outFile.close();
+	if (outFile.getZipError() != UNZ_OK)
+	{
+		return false;
+	}
+	inFile.close();
+
+	return true;
+}
+
+bool MMCZip::compressSubDir(QuaZip* zip, QString dir, QString origDir, QSet<QString>& added,  QString prefix, const SeparatorPrefixTree <'/'> * blacklist)
+{
+	if (!zip) return false;
+	if (zip->getMode()!=QuaZip::mdCreate && zip->getMode()!=QuaZip::mdAppend && zip->getMode()!=QuaZip::mdAdd)
+	{
+		return false;
+	}
+
+	QDir directory(dir);
+	if (!directory.exists())
+	{
+		return false;
+	}
+
+	QDir origDirectory(origDir);
+	if (dir != origDir)
+	{
+		QString internalDirName = origDirectory.relativeFilePath(dir);
+		if(!blacklist || !blacklist->covers(internalDirName))
+		{
+			QuaZipFile dirZipFile(zip);
+			auto dirPrefix = FS::PathCombine(prefix, origDirectory.relativeFilePath(dir)) + "/";
+			if (!dirZipFile.open(QIODevice::WriteOnly, QuaZipNewInfo(dirPrefix, dir), 0, 0, 0))
+			{
+				return false;
+			}
+			dirZipFile.close();
+		}
+	}
+
+	QFileInfoList files = directory.entryInfoList(QDir::AllDirs | QDir::NoDotAndDotDot | QDir::Hidden);
+	for (auto file: files)
+	{
+		if(!file.isDir())
+		{
+			continue;
+		}
+		if(!compressSubDir(zip,file.absoluteFilePath(),origDir, added, prefix, blacklist))
+		{
+			return false;
+		}
+	}
+
+	files = directory.entryInfoList(QDir::Files);
+	for (auto file: files)
+	{
+		if(!file.isFile())
+		{
+			continue;
+		}
+
+		if(file.absoluteFilePath()==zip->getZipName())
+		{
+			continue;
+		}
+
+		QString filename = origDirectory.relativeFilePath(file.absoluteFilePath());
+		if(blacklist && blacklist->covers(filename))
+		{
+			continue;
+		}
+		if(prefix.size())
+		{
+			filename = FS::PathCombine(prefix, filename);
+		}
+		added.insert(filename);
+		if (!compressFile(zip,file.absoluteFilePath(),filename))
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+
+bool MMCZip::mergeZipFiles(QuaZip *into, QFileInfo from, QSet<QString> &contained,
+				   std::function<bool(QString)> filter)
+{
+	QuaZip modZip(from.filePath());
+	modZip.open(QuaZip::mdUnzip);
+
+	QuaZipFile fileInsideMod(&modZip);
+	QuaZipFile zipOutFile(into);
+	for (bool more = modZip.goToFirstFile(); more; more = modZip.goToNextFile())
+	{
+		QString filename = modZip.getCurrentFileName();
+		if (!filter(filename))
+		{
+			qDebug() << "Skipping file " << filename << " from "
+						<< from.fileName() << " - filtered";
+			continue;
+		}
+		if (contained.contains(filename))
+		{
+			qDebug() << "Skipping already contained file " << filename << " from "
+						<< from.fileName();
+			continue;
+		}
+		contained.insert(filename);
+
+		if (!fileInsideMod.open(QIODevice::ReadOnly))
+		{
+			qCritical() << "Failed to open " << filename << " from " << from.fileName();
+			return false;
+		}
+
+		QuaZipNewInfo info_out(fileInsideMod.getActualFileName());
+
+		if (!zipOutFile.open(QIODevice::WriteOnly, info_out))
+		{
+			qCritical() << "Failed to open " << filename << " in the jar";
+			fileInsideMod.close();
+			return false;
+		}
+		if (!copyData(fileInsideMod, zipOutFile))
+		{
+			zipOutFile.close();
+			fileInsideMod.close();
+			qCritical() << "Failed to copy data of " << filename << " into the jar";
+			return false;
+		}
+		zipOutFile.close();
+		fileInsideMod.close();
+	}
+	return true;
+}
+
+bool MMCZip::createModdedJar(QString sourceJarPath, QString targetJarPath, const QList<Mod>& mods)
+{
+	QuaZip zipOut(targetJarPath);
+	if (!zipOut.open(QuaZip::mdCreate))
+	{
+		QFile::remove(targetJarPath);
+		qCritical() << "Failed to open the minecraft.jar for modding";
+		return false;
+	}
+	// Files already added to the jar.
+	// These files will be skipped.
+	QSet<QString> addedFiles;
+
+	// Modify the jar
+	QListIterator<Mod> i(mods);
+    i.toBack();
+    while (i.hasPrevious())
+	{
+		const Mod &mod = i.previous();
+		// do not merge disabled mods.
+		if (!mod.enabled())
+			continue;
+		if (mod.type() == Mod::MOD_ZIPFILE)
+		{
+			if (!mergeZipFiles(&zipOut, mod.filename(), addedFiles, noFilter))
+			{
+				zipOut.close();
+				QFile::remove(targetJarPath);
+				qCritical() << "Failed to add" << mod.filename().fileName() << "to the jar.";
+				return false;
+			}
+		}
+		else if (mod.type() == Mod::MOD_SINGLEFILE)
+		{
+			auto filename = mod.filename();
+			if (!compressFile(&zipOut, filename.absoluteFilePath(),
+										  filename.fileName()))
+			{
+				zipOut.close();
+				QFile::remove(targetJarPath);
+				qCritical() << "Failed to add" << mod.filename().fileName() << "to the jar.";
+				return false;
+			}
+			addedFiles.insert(filename.fileName());
+		}
+		else if (mod.type() == Mod::MOD_FOLDER)
+		{
+			auto filename = mod.filename();
+			QString what_to_zip = filename.absoluteFilePath();
+			QDir dir(what_to_zip);
+			dir.cdUp();
+			QString parent_dir = dir.absolutePath();
+			if (!compressSubDir(&zipOut, what_to_zip, parent_dir, addedFiles))
+			{
+				zipOut.close();
+				QFile::remove(targetJarPath);
+				qCritical() << "Failed to add" << mod.filename().fileName() << "to the jar.";
+				return false;
+			}
+			qDebug() << "Adding folder " << filename.fileName() << " from "
+						<< filename.absoluteFilePath();
+		}
+	}
+
+	if (!mergeZipFiles(&zipOut, QFileInfo(sourceJarPath), addedFiles, metaInfFilter))
+	{
+		zipOut.close();
+		QFile::remove(targetJarPath);
+		qCritical() << "Failed to insert minecraft.jar contents.";
+		return false;
+	}
+
+	// Recompress the jar
+	zipOut.close();
+	if (zipOut.getZipError() != 0)
+	{
+		QFile::remove(targetJarPath);
+		qCritical() << "Failed to finalize minecraft.jar!";
+		return false;
+	}
+	return true;
+}
+
+bool MMCZip::noFilter(QString)
+{
+	return true;
+}
+
+bool MMCZip::metaInfFilter(QString key)
+{
+	if(key.contains("META-INF"))
+	{
+		return false;
+	}
+	return true;
+}
+
+bool MMCZip::compressDir(QString zipFile, QString dir, QString prefix, const SeparatorPrefixTree <'/'> * blacklist)
+{
+	QuaZip zip(zipFile);
+	QDir().mkpath(QFileInfo(zipFile).absolutePath());
+	if(!zip.open(QuaZip::mdCreate))
+	{
+		QFile::remove(zipFile);
+		return false;
+	}
+
+	QSet<QString> added;
+	if (!compressSubDir(&zip, dir, dir, added, prefix, blacklist))
+	{
+		QFile::remove(zipFile);
+		return false;
+	}
+	zip.close();
+	if(zip.getZipError()!=0)
+	{
+		QFile::remove(zipFile);
+		return false;
+	}
+	return true;
+}
+
+QString MMCZip::findFileInZip(QuaZip * zip, const QString & what, const QString &root)
+{
+	QuaZipDir rootDir(zip, root);
+	for(auto fileName: rootDir.entryList(QDir::Files))
+	{
+		if(fileName == what)
+			return root;
+	}
+	for(auto fileName: rootDir.entryList(QDir::Dirs))
+	{
+		QString result = findFileInZip(zip, what, root + fileName);
+		if(!result.isEmpty())
+		{
+			return result;
+		}
+	}
+	return QString();
+}
+
+bool MMCZip::findFilesInZip(QuaZip * zip, const QString & what, QStringList & result, const QString &root)
+{
+	QuaZipDir rootDir(zip, root);
+	for(auto fileName: rootDir.entryList(QDir::Files))
+	{
+		if(fileName == what)
+		{
+			result.append(root);
+			return true;
+		}
+	}
+	for(auto fileName: rootDir.entryList(QDir::Dirs))
+	{
+		findFilesInZip(zip, what, result, root + fileName);
+	}
+	return !result.isEmpty();
+}
+
+bool removeFile(QStringList listFile)
+{
+	bool ret = true;
+	for (int i = 0; i < listFile.count(); i++)
+	{
+		ret &= QFile::remove(listFile.at(i));
+	}
+	return ret;
+}
+
+bool MMCZip::extractFile(QuaZip *zip, const QString &fileName, const QString &fileDest)
+{
+	if(!zip)
+		return false;
+
+	if (zip->getMode() != QuaZip::mdUnzip)
+		return false;
+
+	if (!fileName.isEmpty())
+		zip->setCurrentFile(fileName);
+
+	QuaZipFile inFile(zip);
+	if (!inFile.open(QIODevice::ReadOnly) || inFile.getZipError() != UNZ_OK)
+		return false;
+
+	// Controllo esistenza cartella file risultato
+	QDir curDir;
+	if (fileDest.endsWith('/'))
+	{
+		if (!curDir.mkpath(fileDest))
+		{
+			return false;
+		}
+	}
+	else
+	{
+		if (!curDir.mkpath(QFileInfo(fileDest).absolutePath()))
+		{
+			return false;
+		}
+	}
+
+	QuaZipFileInfo64 info;
+	if (!zip->getCurrentFileInfo(&info))
+		return false;
+
+	QFile::Permissions srcPerm = info.getPermissions();
+	if (fileDest.endsWith('/') && QFileInfo(fileDest).isDir())
+	{
+		if (srcPerm != 0)
+		{
+			QFile(fileDest).setPermissions(srcPerm);
+		}
+		return true;
+	}
+
+	QFile outFile;
+	outFile.setFileName(fileDest);
+	if (!outFile.open(QIODevice::WriteOnly))
+		return false;
+
+	if (!copyData(inFile, outFile) || inFile.getZipError() != UNZ_OK)
+	{
+		outFile.close();
+		removeFile(QStringList(fileDest));
+		return false;
+	}
+	outFile.close();
+
+	inFile.close();
+	if (inFile.getZipError() != UNZ_OK)
+	{
+		removeFile(QStringList(fileDest));
+		return false;
+	}
+
+	if (srcPerm != 0)
+	{
+		outFile.setPermissions(srcPerm);
+	}
+	return true;
+}
+
+QStringList MMCZip::extractSubDir(QuaZip *zip, const QString & subdir, const QString &target)
+{
+	QDir directory(target);
+	QStringList extracted;
+	if (!zip->goToFirstFile())
+	{
+		return QStringList();
+	}
+	do
+	{
+		QString name = zip->getCurrentFileName();
+		if(!name.startsWith(subdir))
+		{
+			continue;
+		}
+		name.remove(0, subdir.size());
+		QString absFilePath = directory.absoluteFilePath(name);
+		if(name.isEmpty())
+		{
+			absFilePath += "/";
+		}
+		if (!extractFile(zip, "", absFilePath))
+		{
+			removeFile(extracted);
+			return QStringList();
+		}
+		extracted.append(absFilePath);
+	} while (zip->goToNextFile());
+	return extracted;
+}
diff --git a/libraries/logic/MMCZip.h b/libraries/logic/MMCZip.h
new file mode 100644
index 00000000..f350e668
--- /dev/null
+++ b/libraries/logic/MMCZip.h
@@ -0,0 +1,88 @@
+#pragma once
+
+#include <QString>
+#include <QFileInfo>
+#include <QSet>
+#include "minecraft/Mod.h"
+#include "SeparatorPrefixTree.h"
+#include <functional>
+
+#include "multimc_logic_export.h"
+
+class QuaZip;
+
+namespace MMCZip
+{
+    /**
+	 * Compress a subdirectory.
+	 * \param parentZip Opened zip containing the parent directory.
+	 * \param dir The full path to the directory to pack.
+	 * \param parentDir The full path to the directory corresponding to the root of the ZIP.
+	 * \param recursive Whether to pack sub-directories as well or only files.
+	 * \return true if success, false otherwise.
+     */
+	bool MULTIMC_LOGIC_EXPORT compressSubDir(QuaZip *zip, QString dir, QString origDir, QSet<QString> &added,
+					QString prefix = QString(), const SeparatorPrefixTree <'/'> * blacklist = nullptr);
+
+	/**
+	 * Compress a whole directory.
+	 * \param fileCompressed The name of the archive.
+	 * \param dir The directory to compress.
+	 * \param recursive Whether to pack the subdirectories as well, or just regular files.
+	 * \return true if success, false otherwise.
+	 */
+	bool MULTIMC_LOGIC_EXPORT compressDir(QString zipFile, QString dir, QString prefix = QString(), const SeparatorPrefixTree <'/'> * blacklist = nullptr);
+
+	/// filter function for @mergeZipFiles - passthrough
+	bool MULTIMC_LOGIC_EXPORT noFilter(QString key);
+
+	/// filter function for @mergeZipFiles - ignores METAINF
+	bool MULTIMC_LOGIC_EXPORT metaInfFilter(QString key);
+
+	/**
+	 * Merge two zip files, using a filter function
+	 */
+	bool MULTIMC_LOGIC_EXPORT mergeZipFiles(QuaZip *into, QFileInfo from, QSet<QString> &contained, std::function<bool(QString)> filter);
+
+	/**
+	 * take a source jar, add mods to it, resulting in target jar
+	 */
+	bool MULTIMC_LOGIC_EXPORT createModdedJar(QString sourceJarPath, QString targetJarPath, const QList<Mod>& mods);
+
+	/**
+	 * Extract a whole archive.
+	 *
+	 * \param fileCompressed The name of the archive.
+	 * \param dir The directory to extract to, the current directory if
+	 * left empty.
+	 * \return The list of the full paths of the files extracted, empty on failure.
+	 */
+	QStringList MULTIMC_LOGIC_EXPORT extractDir(QString fileCompressed, QString dir = QString());
+
+	/**
+	 * Find a single file in archive by file name (not path)
+	 *
+	 * \return the path prefix where the file is
+	 */
+	QString MULTIMC_LOGIC_EXPORT findFileInZip(QuaZip * zip, const QString & what, const QString &root = QString());
+
+	/**
+	 * Find a multiple files of the same name in archive by file name
+	 * If a file is found in a path, no deeper paths are searched
+	 *
+	 * \return true if anything was found
+	 */
+	bool MULTIMC_LOGIC_EXPORT findFilesInZip(QuaZip * zip, const QString & what, QStringList & result, const QString &root = QString());
+
+	/**
+	 * Extract a single file to a destination
+	 *
+	 * \return true if it succeeds
+	 */
+	bool MULTIMC_LOGIC_EXPORT extractFile(QuaZip *zip, const QString &fileName, const QString &fileDest);
+
+	/**
+	 * Extract a subdirectory from an archive
+	 */
+	QStringList MULTIMC_LOGIC_EXPORT extractSubDir(QuaZip *zip, const QString & subdir, const QString &target);
+}
diff --git a/libraries/logic/NullInstance.h b/libraries/logic/NullInstance.h
new file mode 100644
index 00000000..fbb2d985
--- /dev/null
+++ b/libraries/logic/NullInstance.h
@@ -0,0 +1,90 @@
+#pragma once
+#include "BaseInstance.h"
+
+class NullInstance: public BaseInstance
+{
+public:
+	NullInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString& rootDir)
+	:BaseInstance(globalSettings, settings, rootDir)
+	{
+		setFlag(BaseInstance::VersionBrokenFlag);
+	}
+	virtual ~NullInstance() {};
+	virtual bool setIntendedVersionId(QString) override
+	{
+		return false;
+	}
+	virtual void cleanupAfterRun() override
+	{
+	}
+	virtual QString currentVersionId() const override
+	{
+		return "Null";
+	};
+	virtual QString intendedVersionId() const override
+	{
+		return "Null";
+	};
+	virtual void init() override
+	{
+	};
+	virtual QString getStatusbarDescription() override
+	{
+		return tr("Unknown instance type");
+	};
+	virtual bool shouldUpdate() const override
+	{
+		return false;
+	};
+	virtual QSet< QString > traits() override
+	{
+		return {};
+	};
+	virtual QString instanceConfigFolder() const override
+	{
+		return instanceRoot();
+	};
+	virtual std::shared_ptr<LaunchTask> createLaunchTask(AuthSessionPtr) override
+	{
+		return nullptr;
+	}
+	virtual std::shared_ptr< Task > createUpdateTask() override
+	{
+		return nullptr;
+	}
+	virtual std::shared_ptr<Task> createJarModdingTask() override
+	{
+		return nullptr;
+	}
+	virtual void setShouldUpdate(bool) override
+	{
+	};
+	virtual std::shared_ptr< BaseVersionList > versionList() const override
+	{
+		return nullptr;
+	};
+	virtual QProcessEnvironment createEnvironment() override
+	{
+		return QProcessEnvironment();
+	}
+	virtual QMap<QString, QString> getVariables() const override
+	{
+		return QMap<QString, QString>();
+	}
+	virtual IPathMatcher::Ptr getLogFileMatcher() override
+	{
+		return nullptr;
+	}
+	virtual QString getLogFileRoot() override
+	{
+		return instanceRoot();
+	}
+	virtual QString typeName() const override
+	{
+		return "Null";
+	}
+	bool canExport() const override
+	{
+		return false;
+	}
+};
diff --git a/libraries/logic/QObjectPtr.h b/libraries/logic/QObjectPtr.h
new file mode 100644
index 00000000..b81b3234
--- /dev/null
+++ b/libraries/logic/QObjectPtr.h
@@ -0,0 +1,78 @@
+#pragma once
+
+#include <memory>
+#include <QObject>
+
+namespace details
+{
+struct DeleteQObjectLater
+{
+	void operator()(QObject *obj) const
+	{
+		obj->deleteLater();
+	}
+};
+}
+/**
+ * A unique pointer class with unique pointer semantics intended for derivates of QObject
+ * Calls deleteLater() instead of destroying the contained object immediately
+ */
+template<typename T> using unique_qobject_ptr = std::unique_ptr<T, details::DeleteQObjectLater>;
+
+/**
+ * A shared pointer class with shared pointer semantics intended for derivates of QObject
+ * Calls deleteLater() instead of destroying the contained object immediately
+ */
+template <typename T>
+class shared_qobject_ptr
+{
+public:
+	shared_qobject_ptr(){}
+	shared_qobject_ptr(T * wrap)
+	{
+		reset(wrap);
+	}
+	shared_qobject_ptr(const shared_qobject_ptr<T>& other)
+	{
+		m_ptr = other.m_ptr;
+	}
+	template<typename Derived>
+	shared_qobject_ptr(const shared_qobject_ptr<Derived> &other)
+	{
+		m_ptr = other.unwrap();
+	}
+
+public:
+	void reset(T * wrap)
+	{
+		using namespace std::placeholders;
+		m_ptr.reset(wrap, std::bind(&QObject::deleteLater, _1));
+	}
+	void reset()
+	{
+		m_ptr.reset();
+	}
+	T * get() const
+	{
+		return m_ptr.get();
+	}
+	T * operator->() const
+	{
+		return m_ptr.get();
+	}
+	T & operator*() const
+	{
+		return *m_ptr.get();
+	}
+	operator bool() const
+	{
+		return m_ptr.get() != nullptr;
+	}
+	const std::shared_ptr <T> unwrap() const
+	{
+		return m_ptr;
+	}
+
+private:
+	std::shared_ptr <T> m_ptr;
+};
diff --git a/libraries/logic/RWStorage.h b/libraries/logic/RWStorage.h
new file mode 100644
index 00000000..b1598ca4
--- /dev/null
+++ b/libraries/logic/RWStorage.h
@@ -0,0 +1,60 @@
+#pragma once
+template <typename K, typename V>
+class RWStorage
+{
+public:
+	void add(K key, V value)
+	{
+		QWriteLocker l(&lock);
+		cache[key] = value;
+		stale_entries.remove(key);
+	}
+	V get(K key)
+	{
+		QReadLocker l(&lock);
+		if(cache.contains(key))
+		{
+			return cache[key];
+		}
+		else return V();
+	}
+	bool get(K key, V& value)
+	{
+		QReadLocker l(&lock);
+		if(cache.contains(key))
+		{
+			value = cache[key];
+			return true;
+		}
+		else return false;
+	}
+	bool has(K key)
+	{
+		QReadLocker l(&lock);
+		return cache.contains(key);
+	}
+	bool stale(K key)
+	{
+		QReadLocker l(&lock);
+		if(!cache.contains(key))
+			return true;
+		return stale_entries.contains(key);
+	}
+	void setStale(K key)
+	{
+		QReadLocker l(&lock);
+		if(cache.contains(key))
+		{
+			stale_entries.insert(key);
+		}
+	}
+	void clear()
+	{
+		QWriteLocker l(&lock);
+		cache.clear();
+	}
+private:
+	QReadWriteLock lock;
+	QMap<K, V> cache;
+	QSet<K> stale_entries;
+};
\ No newline at end of file
diff --git a/libraries/logic/RecursiveFileSystemWatcher.cpp b/libraries/logic/RecursiveFileSystemWatcher.cpp
new file mode 100644
index 00000000..59c3f0f0
--- /dev/null
+++ b/libraries/logic/RecursiveFileSystemWatcher.cpp
@@ -0,0 +1,111 @@
+#include "RecursiveFileSystemWatcher.h"
+
+#include <QRegularExpression>
+#include <QDebug>
+
+RecursiveFileSystemWatcher::RecursiveFileSystemWatcher(QObject *parent)
+	: QObject(parent), m_watcher(new QFileSystemWatcher(this))
+{
+	connect(m_watcher, &QFileSystemWatcher::fileChanged, this,
+			&RecursiveFileSystemWatcher::fileChange);
+	connect(m_watcher, &QFileSystemWatcher::directoryChanged, this,
+			&RecursiveFileSystemWatcher::directoryChange);
+}
+
+void RecursiveFileSystemWatcher::setRootDir(const QDir &root)
+{
+	bool wasEnabled = m_isEnabled;
+	disable();
+	m_root = root;
+	setFiles(scanRecursive(m_root));
+	if (wasEnabled)
+	{
+		enable();
+	}
+}
+void RecursiveFileSystemWatcher::setWatchFiles(const bool watchFiles)
+{
+	bool wasEnabled = m_isEnabled;
+	disable();
+	m_watchFiles = watchFiles;
+	if (wasEnabled)
+	{
+		enable();
+	}
+}
+
+void RecursiveFileSystemWatcher::enable()
+{
+	if (m_isEnabled)
+	{
+		return;
+	}
+	Q_ASSERT(m_root != QDir::root());
+	addFilesToWatcherRecursive(m_root);
+	m_isEnabled = true;
+}
+void RecursiveFileSystemWatcher::disable()
+{
+	if (!m_isEnabled)
+	{
+		return;
+	}
+	m_isEnabled = false;
+	m_watcher->removePaths(m_watcher->files());
+	m_watcher->removePaths(m_watcher->directories());
+}
+
+void RecursiveFileSystemWatcher::setFiles(const QStringList &files)
+{
+	if (files != m_files)
+	{
+		m_files = files;
+		emit filesChanged();
+	}
+}
+
+void RecursiveFileSystemWatcher::addFilesToWatcherRecursive(const QDir &dir)
+{
+	m_watcher->addPath(dir.absolutePath());
+	for (const QString &directory : dir.entryList(QDir::Dirs | QDir::NoDotAndDotDot))
+	{
+		addFilesToWatcherRecursive(dir.absoluteFilePath(directory));
+	}
+	if (m_watchFiles)
+	{
+		for (const QFileInfo &info : dir.entryInfoList(QDir::Files))
+		{
+			m_watcher->addPath(info.absoluteFilePath());
+		}
+	}
+}
+QStringList RecursiveFileSystemWatcher::scanRecursive(const QDir &directory)
+{
+	QStringList ret;
+	if(!m_matcher)
+	{
+		return {};
+	}
+	for (const QString &dir : directory.entryList(QDir::Dirs | QDir::NoDotAndDotDot | QDir::Hidden))
+	{
+		ret.append(scanRecursive(directory.absoluteFilePath(dir)));
+	}
+	for (const QString &file : directory.entryList(QDir::Files | QDir::Hidden))
+	{
+		auto relPath = m_root.relativeFilePath(directory.absoluteFilePath(file));
+		if (m_matcher->matches(relPath))
+		{
+			ret.append(relPath);
+		}
+	}
+	return ret;
+}
+
+void RecursiveFileSystemWatcher::fileChange(const QString &path)
+{
+	emit fileChanged(path);
+}
+void RecursiveFileSystemWatcher::directoryChange(const QString &path)
+{
+	setFiles(scanRecursive(m_root));
+}
diff --git a/libraries/logic/RecursiveFileSystemWatcher.h b/libraries/logic/RecursiveFileSystemWatcher.h
new file mode 100644
index 00000000..07bce0b9
--- /dev/null
+++ b/libraries/logic/RecursiveFileSystemWatcher.h
@@ -0,0 +1,63 @@
+#pragma once
+
+#include <QFileSystemWatcher>
+#include <QDir>
+#include "pathmatcher/IPathMatcher.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT RecursiveFileSystemWatcher : public QObject
+{
+	Q_OBJECT
+public:
+	RecursiveFileSystemWatcher(QObject *parent);
+
+	void setRootDir(const QDir &root);
+	QDir rootDir() const
+	{
+		return m_root;
+	}
+
+	// WARNING: setting this to true may be bad for performance
+	void setWatchFiles(const bool watchFiles);
+	bool watchFiles() const
+	{
+		return m_watchFiles;
+	}
+
+	void setMatcher(IPathMatcher::Ptr matcher)
+	{
+		m_matcher = matcher;
+	}
+
+	QStringList files() const
+	{
+		return m_files;
+	}
+
+signals:
+	void filesChanged();
+	void fileChanged(const QString &path);
+
+public slots:
+	void enable();
+	void disable();
+
+private:
+	QDir m_root;
+	bool m_watchFiles = false;
+	bool m_isEnabled = false;
+	IPathMatcher::Ptr m_matcher;
+
+	QFileSystemWatcher *m_watcher;
+
+	QStringList m_files;
+	void setFiles(const QStringList &files);
+
+	void addFilesToWatcherRecursive(const QDir &dir);
+	QStringList scanRecursive(const QDir &dir);
+
+private slots:
+	void fileChange(const QString &path);
+	void directoryChange(const QString &path);
+};
diff --git a/libraries/logic/SeparatorPrefixTree.h b/libraries/logic/SeparatorPrefixTree.h
new file mode 100644
index 00000000..fd149af0
--- /dev/null
+++ b/libraries/logic/SeparatorPrefixTree.h
@@ -0,0 +1,298 @@
+#pragma once
+#include <QString>
+#include <QMap>
+#include <QStringList>
+
+template <char Tseparator>
+class SeparatorPrefixTree
+{
+public:
+	SeparatorPrefixTree(QStringList paths)
+	{
+		insert(paths);
+	}
+
+	SeparatorPrefixTree(bool contained = false)
+	{
+		m_contained = contained;
+	}
+
+	void insert(QStringList paths)
+	{
+		for(auto &path: paths)
+		{
+			insert(path);
+		}
+	}
+
+	/// insert an exact path into the tree
+	SeparatorPrefixTree & insert(QString path)
+	{
+		auto sepIndex = path.indexOf(Tseparator);
+		if(sepIndex == -1)
+		{
+			children[path] = SeparatorPrefixTree(true);
+			return children[path];
+		}
+		else
+		{
+			auto prefix = path.left(sepIndex);
+			if(!children.contains(prefix))
+			{
+				children[prefix] = SeparatorPrefixTree(false);
+			}
+			return children[prefix].insert(path.mid(sepIndex + 1));
+		}
+	}
+
+	/// is the path fully contained in the tree?
+	bool contains(QString path) const
+	{
+		auto node = find(path);
+		return node != nullptr;
+	}
+
+	/// does the tree cover a path? That means the prefix of the path is contained in the tree
+	bool covers(QString path) const
+	{
+		// if we found some valid node, it's good enough. the tree covers the path
+		if(m_contained)
+		{
+			return true;
+		}
+		auto sepIndex = path.indexOf(Tseparator);
+		if(sepIndex == -1)
+		{
+			auto found = children.find(path);
+			if(found == children.end())
+			{
+				return false;
+			}
+			return (*found).covers(QString());
+		}
+		else
+		{
+			auto prefix = path.left(sepIndex);
+			auto found = children.find(prefix);
+			if(found == children.end())
+			{
+				return false;
+			}
+			return (*found).covers(path.mid(sepIndex + 1));
+		}
+	}
+
+	/// return the contained path that covers the path specified
+	QString cover(QString path) const
+	{
+		// if we found some valid node, it's good enough. the tree covers the path
+		if(m_contained)
+		{
+			return QString("");
+		}
+		auto sepIndex = path.indexOf(Tseparator);
+		if(sepIndex == -1)
+		{
+			auto found = children.find(path);
+			if(found == children.end())
+			{
+				return QString();
+			}
+			auto nested = (*found).cover(QString());
+			if(nested.isNull())
+			{
+				return nested;
+			}
+			if(nested.isEmpty())
+				return path;
+			return path + Tseparator + nested;
+		}
+		else
+		{
+			auto prefix = path.left(sepIndex);
+			auto found = children.find(prefix);
+			if(found == children.end())
+			{
+				return QString();
+			}
+			auto nested = (*found).cover(path.mid(sepIndex + 1));
+			if(nested.isNull())
+			{
+				return nested;
+			}
+			if(nested.isEmpty())
+				return prefix;
+			return prefix + Tseparator + nested;
+		}
+	}
+
+	/// Does the path-specified node exist in the tree? It does not have to be contained.
+	bool exists(QString path) const
+	{
+		auto sepIndex = path.indexOf(Tseparator);
+		if(sepIndex == -1)
+		{
+			auto found = children.find(path);
+			if(found == children.end())
+			{
+				return false;
+			}
+			return true;
+		}
+		else
+		{
+			auto prefix = path.left(sepIndex);
+			auto found = children.find(prefix);
+			if(found == children.end())
+			{
+				return false;
+			}
+			return (*found).exists(path.mid(sepIndex + 1));
+		}
+	}
+
+	/// find a node in the tree by name
+	const SeparatorPrefixTree * find(QString path) const
+	{
+		auto sepIndex = path.indexOf(Tseparator);
+		if(sepIndex == -1)
+		{
+			auto found = children.find(path);
+			if(found == children.end())
+			{
+				return nullptr;
+			}
+			return &(*found);
+		}
+		else
+		{
+			auto prefix = path.left(sepIndex);
+			auto found = children.find(prefix);
+			if(found == children.end())
+			{
+				return nullptr;
+			}
+			return (*found).find(path.mid(sepIndex + 1));
+		}
+	}
+
+	/// is this a leaf node?
+	bool leaf() const
+	{
+		return children.isEmpty();
+	}
+
+	/// is this node actually contained in the tree, or is it purely structural?
+	bool contained() const
+	{
+		return m_contained;
+	}
+
+	/// Remove a path from the tree
+	bool remove(QString path)
+	{
+		return removeInternal(path) != Failed;
+	}
+
+	/// Clear all children of this node tree node
+	void clear()
+	{
+		children.clear();
+	}
+
+	QStringList toStringList() const
+	{
+		QStringList collected;
+		// collecting these is more expensive.
+		auto iter = children.begin();
+		while(iter != children.end())
+		{
+			QStringList list = iter.value().toStringList();
+			for(int i = 0; i < list.size(); i++)
+			{
+				list[i] = iter.key() + Tseparator + list[i];
+			}
+			collected.append(list);
+			if((*iter).m_contained)
+			{
+				collected.append(iter.key());
+			}
+			iter++;
+		}
+		return collected;
+	}
+private:
+	enum Removal
+	{
+		Failed,
+		Succeeded,
+		HasChildren
+	};
+	Removal removeInternal(QString path = QString())
+	{
+		if(path.isEmpty())
+		{
+			if(!m_contained)
+			{
+				// remove all children - we are removing a prefix
+				clear();
+				return Succeeded;
+			}
+			m_contained = false;
+			if(children.size())
+			{
+				return HasChildren;
+			}
+			return Succeeded;
+		}
+		Removal remStatus = Failed;
+		QString childToRemove;
+		auto sepIndex = path.indexOf(Tseparator);
+		if(sepIndex == -1)
+		{
+			childToRemove = path;
+			auto found = children.find(childToRemove);
+			if(found == children.end())
+			{
+				return Failed;
+			}
+			remStatus = (*found).removeInternal();
+		}
+		else
+		{
+			childToRemove = path.left(sepIndex);
+			auto found = children.find(childToRemove);
+			if(found == children.end())
+			{
+				return Failed;
+			}
+			remStatus = (*found).removeInternal(path.mid(sepIndex + 1));
+		}
+		switch (remStatus)
+		{
+			case Failed:
+			case HasChildren:
+			{
+				return remStatus;
+			}
+			case Succeeded:
+			{
+				children.remove(childToRemove);
+				if(m_contained)
+				{
+					return HasChildren;
+				}
+				if(children.size())
+				{
+					return HasChildren;
+				}
+				return Succeeded;
+			}
+		}
+		return Failed;
+	}
+
+private:
+	QMap<QString,SeparatorPrefixTree<Tseparator>> children;
+	bool m_contained = false;
+};
diff --git a/libraries/logic/TypeMagic.h b/libraries/logic/TypeMagic.h
new file mode 100644
index 00000000..fa9d12a9
--- /dev/null
+++ b/libraries/logic/TypeMagic.h
@@ -0,0 +1,37 @@
+#pragma once
+
+namespace TypeMagic
+{
+/** "Cleans" the given type T by stripping references (&) and cv-qualifiers (const, volatile) from it
+ * const int => int
+ * QString & => QString
+ * const unsigned long long & => unsigned long long
+ *
+ * Usage:
+ *   using Cleaned = Detail::CleanType<const int>;
+ *   static_assert(std::is_same<Cleaned, int>, "Cleaned == int");
+ */
+// the order of remove_cv and remove_reference matters!
+template <typename T>
+using CleanType = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
+
+/// For functors (structs with operator()), including lambdas, which in **most** cases are functors
+/// "Calls" Function<Ret(*)(Arg)> or Function<Ret(C::*)(Arg)>
+template <typename T> struct Function : public Function<decltype(&T::operator())> {};
+/// For function pointers (&function), including static members (&Class::member)
+template <typename Ret, typename Arg> struct Function<Ret(*)(Arg)> : public Function<Ret(Arg)> {};
+/// Default specialization used by others.
+template <typename Ret, typename Arg> struct Function<Ret(Arg)>
+{
+	using ReturnType = Ret;
+	using Argument = Arg;
+};
+/// For member functions. Also used by the lambda overload if the lambda captures [this]
+template <class C, typename Ret, typename Arg> struct Function<Ret(C::*)(Arg)> : public Function<Ret(Arg)> {};
+template <class C, typename Ret, typename Arg> struct Function<Ret(C::*)(Arg) const> : public Function<Ret(Arg)> {};
+/// Overload for references
+template <typename F> struct Function<F&> : public Function<F> {};
+/// Overload for rvalues
+template <typename F> struct Function<F&&> : public Function<F> {};
+// for more info: https://functionalcpp.wordpress.com/2013/08/05/function-traits/
+}
diff --git a/libraries/logic/Version.cpp b/libraries/logic/Version.cpp
new file mode 100644
index 00000000..3c4727ad
--- /dev/null
+++ b/libraries/logic/Version.cpp
@@ -0,0 +1,140 @@
+#include "Version.h"
+
+#include <QStringList>
+#include <QUrl>
+#include <QRegularExpression>
+#include <QRegularExpressionMatch>
+
+Version::Version(const QString &str) : m_string(str)
+{
+	parse();
+}
+
+bool Version::operator<(const Version &other) const
+{
+	const int size = qMax(m_sections.size(), other.m_sections.size());
+	for (int i = 0; i < size; ++i)
+	{
+		const Section sec1 = (i >= m_sections.size()) ? Section("0") : m_sections.at(i);
+		const Section sec2 =
+			(i >= other.m_sections.size()) ? Section("0") : other.m_sections.at(i);
+		if (sec1 != sec2)
+		{
+			return sec1 < sec2;
+		}
+	}
+
+	return false;
+}
+bool Version::operator<=(const Version &other) const
+{
+	return *this < other || *this == other;
+}
+bool Version::operator>(const Version &other) const
+{
+	const int size = qMax(m_sections.size(), other.m_sections.size());
+	for (int i = 0; i < size; ++i)
+	{
+		const Section sec1 = (i >= m_sections.size()) ? Section("0") : m_sections.at(i);
+		const Section sec2 =
+			(i >= other.m_sections.size()) ? Section("0") : other.m_sections.at(i);
+		if (sec1 != sec2)
+		{
+			return sec1 > sec2;
+		}
+	}
+
+	return false;
+}
+bool Version::operator>=(const Version &other) const
+{
+	return *this > other || *this == other;
+}
+bool Version::operator==(const Version &other) const
+{
+	const int size = qMax(m_sections.size(), other.m_sections.size());
+	for (int i = 0; i < size; ++i)
+	{
+		const Section sec1 = (i >= m_sections.size()) ? Section("0") : m_sections.at(i);
+		const Section sec2 =
+			(i >= other.m_sections.size()) ? Section("0") : other.m_sections.at(i);
+		if (sec1 != sec2)
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+bool Version::operator!=(const Version &other) const
+{
+	return !operator==(other);
+}
+
+void Version::parse()
+{
+	m_sections.clear();
+
+	QStringList parts = m_string.split('.');
+
+	for (const auto part : parts)
+	{
+		m_sections.append(Section(part));
+	}
+}
+
+bool versionIsInInterval(const QString &version, const QString &interval)
+{
+	return versionIsInInterval(Version(version), interval);
+}
+bool versionIsInInterval(const Version &version, const QString &interval)
+{
+	if (interval.isEmpty() || version.toString() == interval)
+	{
+		return true;
+	}
+
+	// Interval notation is used
+	QRegularExpression exp(
+		"(?<start>[\\[\\]\\(\\)])(?<bottom>.*?)(,(?<top>.*?))?(?<end>[\\[\\]\\(\\)]),?");
+	QRegularExpressionMatch match = exp.match(interval);
+	if (match.hasMatch())
+	{
+		const QChar start = match.captured("start").at(0);
+		const QChar end = match.captured("end").at(0);
+		const QString bottom = match.captured("bottom");
+		const QString top = match.captured("top");
+
+		// check if in range (bottom)
+		if (!bottom.isEmpty())
+		{
+			const auto bottomVersion = Version(bottom);
+			if ((start == '[') && !(version >= bottomVersion))
+			{
+				return false;
+			}
+			else if ((start == '(') && !(version > bottomVersion))
+			{
+				return false;
+			}
+		}
+
+		// check if in range (top)
+		if (!top.isEmpty())
+		{
+			const auto topVersion = Version(top);
+			if ((end == ']') && !(version <= topVersion))
+			{
+				return false;
+			}
+			else if ((end == ')') && !(version < topVersion))
+			{
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+	return false;
+}
diff --git a/libraries/logic/Version.h b/libraries/logic/Version.h
new file mode 100644
index 00000000..b5946ced
--- /dev/null
+++ b/libraries/logic/Version.h
@@ -0,0 +1,110 @@
+#pragma once
+
+#include <QString>
+#include <QList>
+
+#include "multimc_logic_export.h"
+
+class QUrl;
+
+struct MULTIMC_LOGIC_EXPORT Version
+{
+	Version(const QString &str);
+	Version() {}
+
+	bool operator<(const Version &other) const;
+	bool operator<=(const Version &other) const;
+	bool operator>(const Version &other) const;
+	bool operator>=(const Version &other) const;
+	bool operator==(const Version &other) const;
+	bool operator!=(const Version &other) const;
+
+	QString toString() const
+	{
+		return m_string;
+	}
+
+private:
+	QString m_string;
+	struct Section
+	{
+		explicit Section(const QString &fullString)
+		{
+			m_fullString = fullString;
+			int cutoff = m_fullString.size();
+			for(int i = 0; i < m_fullString.size(); i++)
+			{
+				if(!m_fullString[i].isDigit())
+				{
+					cutoff = i;
+					break;
+				}
+			}
+			auto numPart = m_fullString.leftRef(cutoff);
+			if(numPart.size())
+			{
+				numValid = true;
+				m_numPart = numPart.toInt();
+			}
+			auto stringPart = m_fullString.midRef(cutoff);
+			if(stringPart.size())
+			{
+				m_stringPart = stringPart.toString();
+			}
+		}
+		explicit Section() {}
+		bool numValid = false;
+		int m_numPart = 0;
+		QString m_stringPart;
+		QString m_fullString;
+
+		inline bool operator!=(const Section &other) const
+		{
+			if(numValid && other.numValid)
+			{
+				return m_numPart != other.m_numPart || m_stringPart != other.m_stringPart;
+			}
+			else
+			{
+				return m_fullString != other.m_fullString;
+			}
+		}
+		inline bool operator<(const Section &other) const
+		{
+			if(numValid && other.numValid)
+			{
+				if(m_numPart < other.m_numPart)
+					return true;
+				if(m_numPart == other.m_numPart && m_stringPart < other.m_stringPart)
+					return true;
+				return false;
+			}
+			else
+			{
+				return m_fullString < other.m_fullString;
+			}
+		}
+		inline bool operator>(const Section &other) const
+		{
+			if(numValid && other.numValid)
+			{
+				if(m_numPart > other.m_numPart)
+					return true;
+				if(m_numPart == other.m_numPart && m_stringPart > other.m_stringPart)
+					return true;
+				return false;
+			}
+			else
+			{
+				return m_fullString > other.m_fullString;
+			}
+		}
+	};
+	QList<Section> m_sections;
+
+	void parse();
+};
+
+MULTIMC_LOGIC_EXPORT bool versionIsInInterval(const QString &version, const QString &interval);
+MULTIMC_LOGIC_EXPORT bool versionIsInInterval(const Version &version, const QString &interval);
+
diff --git a/libraries/logic/java/JavaChecker.cpp b/libraries/logic/java/JavaChecker.cpp
new file mode 100644
index 00000000..54d552a9
--- /dev/null
+++ b/libraries/logic/java/JavaChecker.cpp
@@ -0,0 +1,159 @@
+#include "JavaChecker.h"
+#include <FileSystem.h>
+#include <Commandline.h>
+#include <QFile>
+#include <QProcess>
+#include <QMap>
+#include <QCoreApplication>
+#include <QDebug>
+
+JavaChecker::JavaChecker(QObject *parent) : QObject(parent)
+{
+}
+
+void JavaChecker::performCheck()
+{
+	QString checkerJar = FS::PathCombine(QCoreApplication::applicationDirPath(), "jars", "JavaCheck.jar");
+
+	QStringList args;
+
+	process.reset(new QProcess());
+	if(m_args.size())
+	{
+		auto extraArgs = Commandline::splitArgs(m_args);
+		args.append(extraArgs);
+	}
+	if(m_minMem != 0)
+	{
+		args << QString("-Xms%1m").arg(m_minMem);
+	}
+	if(m_maxMem != 0)
+	{
+		args << QString("-Xmx%1m").arg(m_maxMem);
+	}
+	if(m_permGen != 64)
+	{
+		args << QString("-XX:PermSize=%1m").arg(m_permGen);
+	}
+
+	args.append({"-jar", checkerJar});
+	process->setArguments(args);
+	process->setProgram(m_path);
+	process->setProcessChannelMode(QProcess::SeparateChannels);
+	qDebug() << "Running java checker: " + m_path + args.join(" ");;
+
+	connect(process.get(), SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(finished(int, QProcess::ExitStatus)));
+	connect(process.get(), SIGNAL(error(QProcess::ProcessError)), this, SLOT(error(QProcess::ProcessError)));
+	connect(process.get(), SIGNAL(readyReadStandardOutput()), this, SLOT(stdoutReady()));
+	connect(process.get(), SIGNAL(readyReadStandardError()), this, SLOT(stderrReady()));
+	connect(&killTimer, SIGNAL(timeout()), SLOT(timeout()));
+	killTimer.setSingleShot(true);
+	killTimer.start(15000);
+	process->start();
+}
+
+void JavaChecker::stdoutReady()
+{
+	QByteArray data = process->readAllStandardOutput();
+	QString added = QString::fromLocal8Bit(data);
+	added.remove('\r');
+	m_stdout += added;
+}
+
+void JavaChecker::stderrReady()
+{
+	QByteArray data = process->readAllStandardError();
+	QString added = QString::fromLocal8Bit(data);
+	added.remove('\r');
+	m_stderr += added;
+}
+
+void JavaChecker::finished(int exitcode, QProcess::ExitStatus status)
+{
+	killTimer.stop();
+	QProcessPtr _process;
+	_process.swap(process);
+
+	JavaCheckResult result;
+	{
+		result.path = m_path;
+		result.id = m_id;
+	}
+	result.errorLog = m_stderr;
+	qDebug() << "STDOUT" << m_stdout;
+	qWarning() << "STDERR" << m_stderr;
+	qDebug() << "Java checker finished with status " << status << " exit code " << exitcode;
+
+	if (status == QProcess::CrashExit || exitcode == 1)
+	{
+		qDebug() << "Java checker failed!";
+		emit checkFinished(result);
+		return;
+	}
+
+	bool success = true;
+
+	QMap<QString, QString> results;
+	QStringList lines = m_stdout.split("\n", QString::SkipEmptyParts);
+	for(QString line : lines)
+	{
+		line = line.trimmed();
+
+		auto parts = line.split('=', QString::SkipEmptyParts);
+		if(parts.size() != 2 || parts[0].isEmpty() || parts[1].isEmpty())
+		{
+			success = false;
+		}
+		else
+		{
+			results.insert(parts[0], parts[1]);
+		}
+	}
+
+	if(!results.contains("os.arch") || !results.contains("java.version") || !success)
+	{
+		qDebug() << "Java checker failed - couldn't extract required information.";
+		emit checkFinished(result);
+		return;
+	}
+
+	auto os_arch = results["os.arch"];
+	auto java_version = results["java.version"];
+	bool is_64 = os_arch == "x86_64" || os_arch == "amd64";
+
+
+	result.valid = true;
+	result.is_64bit = is_64;
+	result.mojangPlatform = is_64 ? "64" : "32";
+	result.realPlatform = os_arch;
+	result.javaVersion = java_version;
+	qDebug() << "Java checker succeeded.";
+	emit checkFinished(result);
+}
+
+void JavaChecker::error(QProcess::ProcessError err)
+{
+	if(err == QProcess::FailedToStart)
+	{
+		killTimer.stop();
+		qDebug() << "Java checker has failed to start.";
+		JavaCheckResult result;
+		{
+			result.path = m_path;
+			result.id = m_id;
+		}
+
+		emit checkFinished(result);
+		return;
+	}
+}
+
+void JavaChecker::timeout()
+{
+	// NO MERCY. NO ABUSE.
+	if(process)
+	{
+		qDebug() << "Java checker has been killed by timeout.";
+		process->kill();
+	}
+}
diff --git a/libraries/logic/java/JavaChecker.h b/libraries/logic/java/JavaChecker.h
new file mode 100644
index 00000000..650e7ce3
--- /dev/null
+++ b/libraries/logic/java/JavaChecker.h
@@ -0,0 +1,54 @@
+#pragma once
+#include <QProcess>
+#include <QTimer>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+#include "JavaVersion.h"
+
+class JavaChecker;
+
+struct MULTIMC_LOGIC_EXPORT JavaCheckResult
+{
+	QString path;
+	QString mojangPlatform;
+	QString realPlatform;
+	JavaVersion javaVersion;
+	QString errorLog;
+	bool valid = false;
+	bool is_64bit = false;
+	int id;
+};
+
+typedef std::shared_ptr<QProcess> QProcessPtr;
+typedef std::shared_ptr<JavaChecker> JavaCheckerPtr;
+class MULTIMC_LOGIC_EXPORT JavaChecker : public QObject
+{
+	Q_OBJECT
+public:
+	explicit JavaChecker(QObject *parent = 0);
+	void performCheck();
+
+	QString m_path;
+	QString m_args;
+	int m_id = 0;
+	int m_minMem = 0;
+	int m_maxMem = 0;
+	int m_permGen = 64;
+
+signals:
+	void checkFinished(JavaCheckResult result);
+private:
+	QProcessPtr process;
+	QTimer killTimer;
+	QString m_stdout;
+	QString m_stderr;
+public
+slots:
+	void timeout();
+	void finished(int exitcode, QProcess::ExitStatus);
+	void error(QProcess::ProcessError);
+	void stdoutReady();
+	void stderrReady();
+};
diff --git a/libraries/logic/java/JavaCheckerJob.cpp b/libraries/logic/java/JavaCheckerJob.cpp
new file mode 100644
index 00000000..0b040e43
--- /dev/null
+++ b/libraries/logic/java/JavaCheckerJob.cpp
@@ -0,0 +1,45 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "JavaCheckerJob.h"
+
+#include <QDebug>
+
+void JavaCheckerJob::partFinished(JavaCheckResult result)
+{
+	num_finished++;
+	qDebug() << m_job_name.toLocal8Bit() << "progress:" << num_finished << "/"
+				<< javacheckers.size();
+	emit progress(num_finished, javacheckers.size());
+
+	javaresults.replace(result.id, result);
+
+	if (num_finished == javacheckers.size())
+	{
+		emit finished(javaresults);
+	}
+}
+
+void JavaCheckerJob::executeTask()
+{
+	qDebug() << m_job_name.toLocal8Bit() << " started.";
+	m_running = true;
+	for (auto iter : javacheckers)
+	{
+		javaresults.append(JavaCheckResult());
+		connect(iter.get(), SIGNAL(checkFinished(JavaCheckResult)), SLOT(partFinished(JavaCheckResult)));
+		iter->performCheck();
+	}
+}
diff --git a/libraries/logic/java/JavaCheckerJob.h b/libraries/logic/java/JavaCheckerJob.h
new file mode 100644
index 00000000..aca0d02e
--- /dev/null
+++ b/libraries/logic/java/JavaCheckerJob.h
@@ -0,0 +1,84 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QtNetwork>
+#include "JavaChecker.h"
+#include "tasks/Task.h"
+
+class JavaCheckerJob;
+typedef std::shared_ptr<JavaCheckerJob> JavaCheckerJobPtr;
+
+class JavaCheckerJob : public Task
+{
+	Q_OBJECT
+public:
+	explicit JavaCheckerJob(QString job_name) : Task(), m_job_name(job_name) {};
+
+	bool addJavaCheckerAction(JavaCheckerPtr base)
+	{
+		javacheckers.append(base);
+		total_progress++;
+		// if this is already running, the action needs to be started right away!
+		if (isRunning())
+		{
+			setProgress(current_progress, total_progress);
+			connect(base.get(), SIGNAL(checkFinished(JavaCheckResult)), SLOT(partFinished(JavaCheckResult)));
+
+			base->performCheck();
+		}
+		return true;
+	}
+
+	JavaCheckerPtr operator[](int index)
+	{
+		return javacheckers[index];
+	}
+	;
+	JavaCheckerPtr first()
+	{
+		if (javacheckers.size())
+			return javacheckers[0];
+		return JavaCheckerPtr();
+	}
+	int size() const
+	{
+		return javacheckers.size();
+	}
+	virtual bool isRunning() const override
+	{
+		return m_running;
+	}
+
+signals:
+	void started();
+	void finished(QList<JavaCheckResult>);
+
+private slots:
+	void partFinished(JavaCheckResult result);
+
+protected:
+	virtual void executeTask() override;
+
+private:
+	QString m_job_name;
+	QList<JavaCheckerPtr> javacheckers;
+	QList<JavaCheckResult> javaresults;
+	qint64 current_progress = 0;
+	qint64 total_progress = 0;
+	int num_finished = 0;
+	bool m_running = false;
+};
diff --git a/libraries/logic/java/JavaInstall.cpp b/libraries/logic/java/JavaInstall.cpp
new file mode 100644
index 00000000..bb262b6e
--- /dev/null
+++ b/libraries/logic/java/JavaInstall.cpp
@@ -0,0 +1,28 @@
+#include "JavaInstall.h"
+#include <MMCStrings.h>
+
+bool JavaInstall::operator<(const JavaInstall &rhs)
+{
+	auto archCompare = Strings::naturalCompare(arch, rhs.arch, Qt::CaseInsensitive);
+	if(archCompare != 0)
+		return archCompare < 0;
+	if(id < rhs.id)
+	{
+		return true;
+	}
+	if(id > rhs.id)
+	{
+		return false;
+	}
+	return Strings::naturalCompare(path, rhs.path, Qt::CaseInsensitive) < 0;
+}
+
+bool JavaInstall::operator==(const JavaInstall &rhs)
+{
+	return arch == rhs.arch && id == rhs.id && path == rhs.path;
+}
+
+bool JavaInstall::operator>(const JavaInstall &rhs)
+{
+	return (!operator<(rhs)) && (!operator==(rhs));
+}
diff --git a/libraries/logic/java/JavaInstall.h b/libraries/logic/java/JavaInstall.h
new file mode 100644
index 00000000..882c7386
--- /dev/null
+++ b/libraries/logic/java/JavaInstall.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include "BaseVersion.h"
+#include "JavaVersion.h"
+
+struct JavaInstall : public BaseVersion
+{
+	JavaInstall(){}
+	JavaInstall(QString id, QString arch, QString path)
+	: id(id), arch(arch), path(path)
+	{
+	}
+	virtual QString descriptor()
+	{
+		return id.toString();
+	}
+
+	virtual QString name()
+	{
+		return id.toString();
+	}
+
+	virtual QString typeString() const
+	{
+		return arch;
+	}
+
+	bool operator<(const JavaInstall & rhs);
+	bool operator==(const JavaInstall & rhs);
+	bool operator>(const JavaInstall & rhs);
+
+	JavaVersion id;
+	QString arch;
+	QString path;
+	bool recommended = false;
+};
+
+typedef std::shared_ptr<JavaInstall> JavaInstallPtr;
diff --git a/libraries/logic/java/JavaInstallList.cpp b/libraries/logic/java/JavaInstallList.cpp
new file mode 100644
index 00000000..c0729227
--- /dev/null
+++ b/libraries/logic/java/JavaInstallList.cpp
@@ -0,0 +1,186 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QtNetwork>
+#include <QtXml>
+#include <QRegExp>
+
+#include <QDebug>
+
+#include "java/JavaInstallList.h"
+#include "java/JavaCheckerJob.h"
+#include "java/JavaUtils.h"
+#include "MMCStrings.h"
+#include "minecraft/VersionFilterData.h"
+
+JavaInstallList::JavaInstallList(QObject *parent) : BaseVersionList(parent)
+{
+}
+
+Task *JavaInstallList::getLoadTask()
+{
+	return new JavaListLoadTask(this);
+}
+
+const BaseVersionPtr JavaInstallList::at(int i) const
+{
+	return m_vlist.at(i);
+}
+
+bool JavaInstallList::isLoaded()
+{
+	return m_loaded;
+}
+
+int JavaInstallList::count() const
+{
+	return m_vlist.count();
+}
+
+QVariant JavaInstallList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	auto version = std::dynamic_pointer_cast<JavaInstall>(m_vlist[index.row()]);
+	switch (role)
+	{
+		case VersionPointerRole:
+			return qVariantFromValue(m_vlist[index.row()]);
+		case VersionIdRole:
+			return version->descriptor();
+		case VersionRole:
+			return version->id.toString();
+		case RecommendedRole:
+			return version->recommended;
+		case PathRole:
+			return version->path;
+		case ArchitectureRole:
+			return version->arch;
+		default:
+			return QVariant();
+	}
+}
+
+BaseVersionList::RoleList JavaInstallList::providesRoles() const
+{
+	return {VersionPointerRole, VersionIdRole, VersionRole, RecommendedRole, PathRole, ArchitectureRole};
+}
+
+
+void JavaInstallList::updateListData(QList<BaseVersionPtr> versions)
+{
+	beginResetModel();
+	m_vlist = versions;
+	m_loaded = true;
+	sortVersions();
+	if(m_vlist.size())
+	{
+		auto best = std::dynamic_pointer_cast<JavaInstall>(m_vlist[0]);
+		best->recommended = true;
+	}
+	endResetModel();
+}
+
+bool sortJavas(BaseVersionPtr left, BaseVersionPtr right)
+{
+	auto rleft = std::dynamic_pointer_cast<JavaInstall>(left);
+	auto rright = std::dynamic_pointer_cast<JavaInstall>(right);
+	return (*rleft) > (*rright);
+}
+
+void JavaInstallList::sortVersions()
+{
+	beginResetModel();
+	std::sort(m_vlist.begin(), m_vlist.end(), sortJavas);
+	endResetModel();
+}
+
+JavaListLoadTask::JavaListLoadTask(JavaInstallList *vlist) : Task()
+{
+	m_list = vlist;
+	m_currentRecommended = NULL;
+}
+
+JavaListLoadTask::~JavaListLoadTask()
+{
+}
+
+void JavaListLoadTask::executeTask()
+{
+	setStatus(tr("Detecting Java installations..."));
+
+	JavaUtils ju;
+	QList<QString> candidate_paths = ju.FindJavaPaths();
+
+	m_job = std::shared_ptr<JavaCheckerJob>(new JavaCheckerJob("Java detection"));
+	connect(m_job.get(), SIGNAL(finished(QList<JavaCheckResult>)), this, SLOT(javaCheckerFinished(QList<JavaCheckResult>)));
+	connect(m_job.get(), &Task::progress, this, &Task::setProgress);
+
+	qDebug() << "Probing the following Java paths: ";
+	int id = 0;
+	for(QString candidate : candidate_paths)
+	{
+		qDebug() << " " << candidate;
+
+		auto candidate_checker = new JavaChecker();
+		candidate_checker->m_path = candidate;
+		candidate_checker->m_id = id;
+		m_job->addJavaCheckerAction(JavaCheckerPtr(candidate_checker));
+
+		id++;
+	}
+
+	m_job->start();
+}
+
+void JavaListLoadTask::javaCheckerFinished(QList<JavaCheckResult> results)
+{
+	QList<JavaInstallPtr> candidates;
+
+	qDebug() << "Found the following valid Java installations:";
+	for(JavaCheckResult result : results)
+	{
+		if(result.valid)
+		{
+			JavaInstallPtr javaVersion(new JavaInstall());
+
+			javaVersion->id = result.javaVersion;
+			javaVersion->arch = result.mojangPlatform;
+			javaVersion->path = result.path;
+			candidates.append(javaVersion);
+
+			qDebug() << " " << javaVersion->id.toString() << javaVersion->arch << javaVersion->path;
+		}
+	}
+
+	QList<BaseVersionPtr> javas_bvp;
+	for (auto java : candidates)
+	{
+		//qDebug() << java->id << java->arch << " at " << java->path;
+		BaseVersionPtr bp_java = std::dynamic_pointer_cast<BaseVersion>(java);
+
+		if (bp_java)
+		{
+			javas_bvp.append(java);
+		}
+	}
+
+	m_list->updateListData(javas_bvp);
+	emitSucceeded();
+}
diff --git a/libraries/logic/java/JavaInstallList.h b/libraries/logic/java/JavaInstallList.h
new file mode 100644
index 00000000..cf0e5784
--- /dev/null
+++ b/libraries/logic/java/JavaInstallList.h
@@ -0,0 +1,71 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QAbstractListModel>
+
+#include "BaseVersionList.h"
+#include "tasks/Task.h"
+
+#include "JavaCheckerJob.h"
+#include "JavaInstall.h"
+
+#include "multimc_logic_export.h"
+
+class JavaListLoadTask;
+
+class MULTIMC_LOGIC_EXPORT JavaInstallList : public BaseVersionList
+{
+	Q_OBJECT
+public:
+	explicit JavaInstallList(QObject *parent = 0);
+
+	virtual Task *getLoadTask() override;
+	virtual bool isLoaded() override;
+	virtual const BaseVersionPtr at(int i) const override;
+	virtual int count() const override;
+	virtual void sortVersions() override;
+
+	virtual QVariant data(const QModelIndex &index, int role) const override;
+	virtual RoleList providesRoles() const override;
+
+public slots:
+	virtual void updateListData(QList<BaseVersionPtr> versions) override;
+
+protected:
+	QList<BaseVersionPtr> m_vlist;
+
+	bool m_loaded = false;
+};
+
+class JavaListLoadTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit JavaListLoadTask(JavaInstallList *vlist);
+	~JavaListLoadTask();
+
+	virtual void executeTask();
+public slots:
+	void javaCheckerFinished(QList<JavaCheckResult> results);
+
+protected:
+	std::shared_ptr<JavaCheckerJob> m_job;
+	JavaInstallList *m_list;
+	JavaInstall *m_currentRecommended;
+};
diff --git a/libraries/logic/java/JavaUtils.cpp b/libraries/logic/java/JavaUtils.cpp
new file mode 100644
index 00000000..88996e9f
--- /dev/null
+++ b/libraries/logic/java/JavaUtils.cpp
@@ -0,0 +1,219 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QStringList>
+#include <QString>
+#include <QDir>
+#include <QStringList>
+
+#include <settings/Setting.h>
+
+#include <QDebug>
+#include "java/JavaUtils.h"
+#include "java/JavaCheckerJob.h"
+#include "java/JavaInstallList.h"
+#include "FileSystem.h"
+
+JavaUtils::JavaUtils()
+{
+}
+
+JavaInstallPtr JavaUtils::MakeJavaPtr(QString path, QString id, QString arch)
+{
+	JavaInstallPtr javaVersion(new JavaInstall());
+
+	javaVersion->id = id;
+	javaVersion->arch = arch;
+	javaVersion->path = path;
+
+	return javaVersion;
+}
+
+JavaInstallPtr JavaUtils::GetDefaultJava()
+{
+	JavaInstallPtr javaVersion(new JavaInstall());
+
+	javaVersion->id = "java";
+	javaVersion->arch = "unknown";
+	javaVersion->path = "java";
+
+	return javaVersion;
+}
+
+#if defined(Q_OS_WIN32)
+QList<JavaInstallPtr> JavaUtils::FindJavaFromRegistryKey(DWORD keyType, QString keyName)
+{
+	QList<JavaInstallPtr> javas;
+
+	QString archType = "unknown";
+	if (keyType == KEY_WOW64_64KEY)
+		archType = "64";
+	else if (keyType == KEY_WOW64_32KEY)
+		archType = "32";
+
+	HKEY jreKey;
+	if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, keyName.toStdString().c_str(), 0,
+					  KEY_READ | keyType | KEY_ENUMERATE_SUB_KEYS, &jreKey) == ERROR_SUCCESS)
+	{
+		// Read the current type version from the registry.
+		// This will be used to find any key that contains the JavaHome value.
+		char *value = new char[0];
+		DWORD valueSz = 0;
+		if (RegQueryValueExA(jreKey, "CurrentVersion", NULL, NULL, (BYTE *)value, &valueSz) ==
+			ERROR_MORE_DATA)
+		{
+			value = new char[valueSz];
+			RegQueryValueExA(jreKey, "CurrentVersion", NULL, NULL, (BYTE *)value, &valueSz);
+		}
+
+		QString recommended = value;
+
+		TCHAR subKeyName[255];
+		DWORD subKeyNameSize, numSubKeys, retCode;
+
+		// Get the number of subkeys
+		RegQueryInfoKey(jreKey, NULL, NULL, NULL, &numSubKeys, NULL, NULL, NULL, NULL, NULL,
+						NULL, NULL);
+
+		// Iterate until RegEnumKeyEx fails
+		if (numSubKeys > 0)
+		{
+			for (int i = 0; i < numSubKeys; i++)
+			{
+				subKeyNameSize = 255;
+				retCode = RegEnumKeyEx(jreKey, i, subKeyName, &subKeyNameSize, NULL, NULL, NULL,
+									   NULL);
+				if (retCode == ERROR_SUCCESS)
+				{
+					// Now open the registry key for the version that we just got.
+					QString newKeyName = keyName + "\\" + subKeyName;
+
+					HKEY newKey;
+					if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, newKeyName.toStdString().c_str(), 0,
+									 KEY_READ | KEY_WOW64_64KEY, &newKey) == ERROR_SUCCESS)
+					{
+						// Read the JavaHome value to find where Java is installed.
+						value = new char[0];
+						valueSz = 0;
+						if (RegQueryValueEx(newKey, "JavaHome", NULL, NULL, (BYTE *)value,
+											&valueSz) == ERROR_MORE_DATA)
+						{
+							value = new char[valueSz];
+							RegQueryValueEx(newKey, "JavaHome", NULL, NULL, (BYTE *)value,
+											&valueSz);
+
+							// Now, we construct the version object and add it to the list.
+							JavaInstallPtr javaVersion(new JavaInstall());
+
+							javaVersion->id = subKeyName;
+							javaVersion->arch = archType;
+							javaVersion->path =
+								QDir(FS::PathCombine(value, "bin")).absoluteFilePath("javaw.exe");
+							javas.append(javaVersion);
+						}
+
+						RegCloseKey(newKey);
+					}
+				}
+			}
+		}
+
+		RegCloseKey(jreKey);
+	}
+
+	return javas;
+}
+
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	QList<JavaInstallPtr> java_candidates;
+
+	QList<JavaInstallPtr> JRE64s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_64KEY, "SOFTWARE\\JavaSoft\\Java Runtime Environment");
+	QList<JavaInstallPtr> JDK64s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_64KEY, "SOFTWARE\\JavaSoft\\Java Development Kit");
+	QList<JavaInstallPtr> JRE32s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_32KEY, "SOFTWARE\\JavaSoft\\Java Runtime Environment");
+	QList<JavaInstallPtr> JDK32s = this->FindJavaFromRegistryKey(
+		KEY_WOW64_32KEY, "SOFTWARE\\JavaSoft\\Java Development Kit");
+
+	java_candidates.append(JRE64s);
+	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre7/bin/javaw.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files/Java/jre6/bin/javaw.exe"));
+	java_candidates.append(JDK64s);
+	java_candidates.append(JRE32s);
+	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre7/bin/javaw.exe"));
+	java_candidates.append(MakeJavaPtr("C:/Program Files (x86)/Java/jre6/bin/javaw.exe"));
+	java_candidates.append(JDK32s);
+	java_candidates.append(MakeJavaPtr(this->GetDefaultJava()->path));
+
+	QList<QString> candidates;
+	for(JavaInstallPtr java_candidate : java_candidates)
+	{
+		if(!candidates.contains(java_candidate->path))
+		{
+			candidates.append(java_candidate->path);
+		}
+	}
+
+	return candidates;
+}
+
+#elif defined(Q_OS_MAC)
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	QList<QString> javas;
+	javas.append(this->GetDefaultJava()->path);
+	javas.append("/Applications/Xcode.app/Contents/Applications/Application Loader.app/Contents/MacOS/itms/java/bin/java");
+	javas.append("/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java");
+	javas.append("/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java");
+	QDir libraryJVMDir("/Library/Java/JavaVirtualMachines/");
+	QStringList libraryJVMJavas = libraryJVMDir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
+	foreach (const QString &java, libraryJVMJavas) {
+		javas.append(libraryJVMDir.absolutePath() + "/" + java + "/Contents/Home/bin/java");
+		javas.append(libraryJVMDir.absolutePath() + "/" + java + "/Contents/Home/jre/bin/java");
+	}
+	QDir systemLibraryJVMDir("/System/Library/Java/JavaVirtualMachines/");
+	QStringList systemLibraryJVMJavas = systemLibraryJVMDir.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
+	foreach (const QString &java, systemLibraryJVMJavas) {
+		javas.append(systemLibraryJVMDir.absolutePath() + "/" + java + "/Contents/Home/bin/java");
+		javas.append(systemLibraryJVMDir.absolutePath() + "/" + java + "/Contents/Commands/java");
+	}
+	return javas;
+}
+
+#elif defined(Q_OS_LINUX)
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	qDebug() << "Linux Java detection incomplete - defaulting to \"java\"";
+
+	QList<QString> javas;
+	javas.append(this->GetDefaultJava()->path);
+    javas.append("/opt/java/bin/java");
+    javas.append("/usr/bin/java");
+
+	return javas;
+}
+#else
+QList<QString> JavaUtils::FindJavaPaths()
+{
+	qDebug() << "Unknown operating system build - defaulting to \"java\"";
+
+	QList<QString> javas;
+	javas.append(this->GetDefaultJava()->path);
+
+	return javas;
+}
+#endif
diff --git a/libraries/logic/java/JavaUtils.h b/libraries/logic/java/JavaUtils.h
new file mode 100644
index 00000000..3fb88341
--- /dev/null
+++ b/libraries/logic/java/JavaUtils.h
@@ -0,0 +1,43 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QStringList>
+
+#include "JavaCheckerJob.h"
+#include "JavaChecker.h"
+#include "JavaInstallList.h"
+
+#ifdef Q_OS_WIN
+#include <windows.h>
+#endif
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT JavaUtils : public QObject
+{
+	Q_OBJECT
+public:
+	JavaUtils();
+
+	JavaInstallPtr MakeJavaPtr(QString path, QString id = "unknown", QString arch = "unknown");
+	QList<QString> FindJavaPaths();
+	JavaInstallPtr GetDefaultJava();
+
+#ifdef Q_OS_WIN
+	QList<JavaInstallPtr> FindJavaFromRegistryKey(DWORD keyType, QString keyName);
+#endif
+};
diff --git a/libraries/logic/java/JavaVersion.cpp b/libraries/logic/java/JavaVersion.cpp
new file mode 100644
index 00000000..84fc48a4
--- /dev/null
+++ b/libraries/logic/java/JavaVersion.cpp
@@ -0,0 +1,112 @@
+#include "JavaVersion.h"
+#include <MMCStrings.h>
+
+#include <QRegularExpression>
+#include <QString>
+
+JavaVersion & JavaVersion::operator=(const QString & javaVersionString)
+{
+	string = javaVersionString;
+
+	auto getCapturedInteger = [](const QRegularExpressionMatch & match, const QString &what) -> int
+	{
+		auto str = match.captured(what);
+		if(str.isEmpty())
+		{
+			return 0;
+		}
+		return str.toInt();
+	};
+
+	QRegularExpression pattern;
+	if(javaVersionString.startsWith("1."))
+	{
+		pattern = QRegularExpression ("1[.](?<major>[0-9]+)([.](?<minor>[0-9]+))?(_(?<security>[0-9]+)?)?(-(?<prerelease>[a-zA-Z0-9]+))?");
+	}
+	else
+	{
+		pattern = QRegularExpression("(?<major>[0-9]+)([.](?<minor>[0-9]+))?([.](?<security>[0-9]+))?(-(?<prerelease>[a-zA-Z0-9]+))?");
+	}
+
+	auto match = pattern.match(string);
+	parseable = match.hasMatch();
+	major = getCapturedInteger(match, "major");
+	minor = getCapturedInteger(match, "minor");
+	security = getCapturedInteger(match, "security");
+	prerelease = match.captured("prerelease");
+	return *this;
+}
+
+JavaVersion::JavaVersion(const QString &rhs)
+{
+	operator=(rhs);
+}
+
+QString JavaVersion::toString()
+{
+	return string;
+}
+
+bool JavaVersion::requiresPermGen()
+{
+	if(parseable)
+	{
+		return major < 8;
+	}
+	return true;
+}
+
+bool JavaVersion::operator<(const JavaVersion &rhs)
+{
+	if(parseable && rhs.parseable)
+	{
+		if(major < rhs.major)
+			return true;
+		if(major > rhs.major)
+			return false;
+		if(minor < rhs.minor)
+			return true;
+		if(minor > rhs.minor)
+			return false;
+		if(security < rhs.security)
+			return true;
+		if(security > rhs.security)
+			return false;
+
+		// everything else being equal, consider prerelease status
+		bool thisPre = !prerelease.isEmpty();
+		bool rhsPre = !rhs.prerelease.isEmpty();
+		if(thisPre && !rhsPre)
+		{
+			// this is a prerelease and the other one isn't -> lesser
+			return true;
+		}
+		else if(!thisPre && rhsPre)
+		{
+			// this isn't a prerelease and the other one is -> greater
+			return false;
+		}
+		else if(thisPre && rhsPre)
+		{
+			// both are prereleases - use natural compare...
+			return Strings::naturalCompare(prerelease, rhs.prerelease, Qt::CaseSensitive) < 0;
+		}
+		// neither is prerelease, so they are the same -> this cannot be less than rhs
+		return false;
+	}
+	else return Strings::naturalCompare(string, rhs.string, Qt::CaseSensitive) < 0;
+}
+
+bool JavaVersion::operator==(const JavaVersion &rhs)
+{
+	if(parseable && rhs.parseable)
+	{
+		return major == rhs.major && minor == rhs.minor && security == rhs.security && prerelease == rhs.prerelease;
+	}
+	return string == rhs.string;
+}
+
+bool JavaVersion::operator>(const JavaVersion &rhs)
+{
+	return (!operator<(rhs)) && (!operator==(rhs));
+}
diff --git a/libraries/logic/java/JavaVersion.h b/libraries/logic/java/JavaVersion.h
new file mode 100644
index 00000000..f9a733d3
--- /dev/null
+++ b/libraries/logic/java/JavaVersion.h
@@ -0,0 +1,30 @@
+#pragma once
+
+#include "multimc_logic_export.h"
+#include <QString>
+
+class MULTIMC_LOGIC_EXPORT JavaVersion
+{
+	friend class JavaVersionTest;
+public:
+	JavaVersion() {};
+	JavaVersion(const QString & rhs);
+
+	JavaVersion & operator=(const QString & rhs);
+
+	bool operator<(const JavaVersion & rhs);
+	bool operator==(const JavaVersion & rhs);
+	bool operator>(const JavaVersion & rhs);
+
+	bool requiresPermGen();
+
+	QString toString();
+
+private:
+	QString string;
+	int major = 0;
+	int minor = 0;
+	int security = 0;
+	bool parseable = false;
+	QString prerelease;
+};
diff --git a/libraries/logic/launch/LaunchStep.cpp b/libraries/logic/launch/LaunchStep.cpp
new file mode 100644
index 00000000..3078043b
--- /dev/null
+++ b/libraries/logic/launch/LaunchStep.cpp
@@ -0,0 +1,27 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LaunchStep.h"
+#include "LaunchTask.h"
+
+void LaunchStep::bind(LaunchTask *parent)
+{
+	m_parent = parent;
+	connect(this, &LaunchStep::readyForLaunch, parent, &LaunchTask::onReadyForLaunch);
+	connect(this, &LaunchStep::logLine, parent, &LaunchTask::onLogLine);
+	connect(this, &LaunchStep::logLines, parent, &LaunchTask::onLogLines);
+	connect(this, &LaunchStep::finished, parent, &LaunchTask::onStepFinished);
+	connect(this, &LaunchStep::progressReportingRequest, parent, &LaunchTask::onProgressReportingRequested);
+}
diff --git a/libraries/logic/launch/LaunchStep.h b/libraries/logic/launch/LaunchStep.h
new file mode 100644
index 00000000..ea472c0d
--- /dev/null
+++ b/libraries/logic/launch/LaunchStep.h
@@ -0,0 +1,48 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "tasks/Task.h"
+#include "MessageLevel.h"
+
+#include <QStringList>
+
+class LaunchTask;
+class LaunchStep: public Task
+{
+	Q_OBJECT
+public: /* methods */
+	explicit LaunchStep(LaunchTask *parent):Task(nullptr), m_parent(parent)
+	{
+		bind(parent);
+	};
+	virtual ~LaunchStep() {};
+
+protected: /* methods */
+	virtual void bind(LaunchTask *parent);
+
+signals:
+	void logLines(QStringList lines, MessageLevel::Enum level);
+	void logLine(QString line, MessageLevel::Enum level);
+	void readyForLaunch();
+	void progressReportingRequest();
+
+public slots:
+	virtual void proceed() {};
+
+protected: /* data */
+	LaunchTask *m_parent;
+};
\ No newline at end of file
diff --git a/libraries/logic/launch/LaunchTask.cpp b/libraries/logic/launch/LaunchTask.cpp
new file mode 100644
index 00000000..5b7ff182
--- /dev/null
+++ b/libraries/logic/launch/LaunchTask.cpp
@@ -0,0 +1,228 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "launch/LaunchTask.h"
+#include "MessageLevel.h"
+#include "MMCStrings.h"
+#include "java/JavaChecker.h"
+#include "tasks/Task.h"
+#include <QDebug>
+#include <QDir>
+#include <QEventLoop>
+#include <QRegularExpression>
+#include <QCoreApplication>
+#include <QStandardPaths>
+#include <assert.h>
+
+void LaunchTask::init()
+{
+	m_instance->setRunning(true);
+}
+
+std::shared_ptr<LaunchTask> LaunchTask::create(InstancePtr inst)
+{
+	std::shared_ptr<LaunchTask> proc(new LaunchTask(inst));
+	proc->init();
+	return proc;
+}
+
+LaunchTask::LaunchTask(InstancePtr instance): m_instance(instance)
+{
+}
+
+void LaunchTask::appendStep(std::shared_ptr<LaunchStep> step)
+{
+	m_steps.append(step);
+}
+
+void LaunchTask::prependStep(std::shared_ptr<LaunchStep> step)
+{
+	m_steps.prepend(step);
+}
+
+void LaunchTask::executeTask()
+{
+	if(!m_steps.size())
+	{
+		state = LaunchTask::Finished;
+		emitSucceeded();
+	}
+	state = LaunchTask::Running;
+	onStepFinished();
+}
+
+void LaunchTask::onReadyForLaunch()
+{
+	state = LaunchTask::Waiting;
+	emit readyForLaunch();
+}
+
+void LaunchTask::onStepFinished()
+{
+	// initial -> just start the first step
+	if(currentStep == -1)
+	{
+		currentStep ++;
+		m_steps[currentStep]->start();
+		return;
+	}
+
+	auto step = m_steps[currentStep];
+	if(step->successful())
+	{
+		// end?
+		if(currentStep == m_steps.size() - 1)
+		{
+			emitSucceeded();
+		}
+		else
+		{
+			currentStep ++;
+			step = m_steps[currentStep];
+			step->start();
+		}
+	}
+	else
+	{
+		emitFailed(step->failReason());
+	}
+}
+
+void LaunchTask::onProgressReportingRequested()
+{
+	state = LaunchTask::Waiting;
+	emit requestProgress(m_steps[currentStep].get());
+}
+
+void LaunchTask::setCensorFilter(QMap<QString, QString> filter)
+{
+	m_censorFilter = filter;
+}
+
+QString LaunchTask::censorPrivateInfo(QString in)
+{
+	auto iter = m_censorFilter.begin();
+	while (iter != m_censorFilter.end())
+	{
+		in.replace(iter.key(), iter.value());
+		iter++;
+	}
+	return in;
+}
+
+void LaunchTask::proceed()
+{
+	if(state != LaunchTask::Waiting)
+	{
+		return;
+	}
+	m_steps[currentStep]->proceed();
+}
+
+bool LaunchTask::abort()
+{
+	switch(state)
+	{
+		case LaunchTask::Aborted:
+		case LaunchTask::Failed:
+		case LaunchTask::Finished:
+			return true;
+		case LaunchTask::NotStarted:
+		{
+			state = LaunchTask::Aborted;
+			emitFailed("Aborted");
+			return true;
+		}
+		case LaunchTask::Running:
+		case LaunchTask::Waiting:
+		{
+			auto step = m_steps[currentStep];
+			if(!step->canAbort())
+			{
+				return false;
+			}
+			if(step->abort())
+			{
+				state = LaunchTask::Aborted;
+				return true;
+			}
+		}
+		default:
+			break;
+	}
+	return false;
+}
+
+void LaunchTask::onLogLines(const QStringList &lines, MessageLevel::Enum defaultLevel)
+{
+	for (auto & line: lines)
+	{
+		onLogLine(line, defaultLevel);
+	}
+}
+
+void LaunchTask::onLogLine(QString line, MessageLevel::Enum level)
+{
+	// if the launcher part set a log level, use it
+	auto innerLevel = MessageLevel::fromLine(line);
+	if(innerLevel != MessageLevel::Unknown)
+	{
+		level = innerLevel;
+	}
+
+	// If the level is still undetermined, guess level
+	if (level == MessageLevel::StdErr || level == MessageLevel::StdOut || level == MessageLevel::Unknown)
+	{
+		level = m_instance->guessLevel(line, level);
+	}
+
+	// censor private user info
+	line = censorPrivateInfo(line);
+
+	emit log(line, level);
+}
+
+void LaunchTask::emitSucceeded()
+{
+	m_instance->cleanupAfterRun();
+	m_instance->setRunning(false);
+	Task::emitSucceeded();
+}
+
+void LaunchTask::emitFailed(QString reason)
+{
+	m_instance->cleanupAfterRun();
+	m_instance->setRunning(false);
+	Task::emitFailed(reason);
+}
+
+QString LaunchTask::substituteVariables(const QString &cmd) const
+{
+	QString out = cmd;
+	auto variables = m_instance->getVariables();
+	for (auto it = variables.begin(); it != variables.end(); ++it)
+	{
+		out.replace("$" + it.key(), it.value());
+	}
+	auto env = QProcessEnvironment::systemEnvironment();
+	for (auto var : env.keys())
+	{
+		out.replace("$" + var, env.value(var));
+	}
+	return out;
+}
+
diff --git a/libraries/logic/launch/LaunchTask.h b/libraries/logic/launch/LaunchTask.h
new file mode 100644
index 00000000..447445ca
--- /dev/null
+++ b/libraries/logic/launch/LaunchTask.h
@@ -0,0 +1,122 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	 http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QProcess>
+#include "BaseInstance.h"
+#include "MessageLevel.h"
+#include "LoggedProcess.h"
+#include "LaunchStep.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT LaunchTask: public Task
+{
+	Q_OBJECT
+protected:
+	explicit LaunchTask(InstancePtr instance);
+	void init();
+
+public:
+	enum State
+	{
+		NotStarted,
+		Running,
+		Waiting,
+		Failed,
+		Aborted,
+		Finished
+	};
+
+public: /* methods */
+	static std::shared_ptr<LaunchTask> create(InstancePtr inst);
+	virtual ~LaunchTask() {};
+
+	void appendStep(std::shared_ptr<LaunchStep> step);
+	void prependStep(std::shared_ptr<LaunchStep> step);
+	void setCensorFilter(QMap<QString, QString> filter);
+
+	InstancePtr instance()
+	{
+		return m_instance;
+	}
+
+	void setPid(qint64 pid)
+	{
+		m_pid = pid;
+	}
+
+	qint64 pid()
+	{
+		return m_pid;
+	}
+
+	/**
+	 * @brief prepare the process for launch (for multi-stage launch)
+	 */
+	virtual void executeTask() override;
+
+	/**
+	 * @brief launch the armed instance
+	 */
+	void proceed();
+
+	/**
+	 * @brief abort launch
+	 */
+	virtual bool abort() override;
+
+public:
+	QString substituteVariables(const QString &cmd) const;
+	QString censorPrivateInfo(QString in);
+
+protected: /* methods */
+	virtual void emitFailed(QString reason) override;
+	virtual void emitSucceeded() override;
+
+signals:
+	/**
+	 * @brief emitted when the launch preparations are done
+	 */
+	void readyForLaunch();
+
+	void requestProgress(Task *task);
+
+	void requestLogging();
+
+	/**
+	 * @brief emitted when we want to log something
+	 * @param text the text to log
+	 * @param level the level to log at
+	 */
+	void log(QString text, MessageLevel::Enum level = MessageLevel::MultiMC);
+
+public slots:
+	void onLogLines(const QStringList& lines, MessageLevel::Enum defaultLevel = MessageLevel::MultiMC);
+	void onLogLine(QString line, MessageLevel::Enum defaultLevel = MessageLevel::MultiMC);
+	void onReadyForLaunch();
+	void onStepFinished();
+	void onProgressReportingRequested();
+
+protected: /* data */
+	InstancePtr m_instance;
+	QList <std::shared_ptr<LaunchStep>> m_steps;
+	QMap<QString, QString> m_censorFilter;
+	int currentStep = -1;
+	State state = NotStarted;
+	qint64 m_pid = -1;
+};
diff --git a/libraries/logic/launch/LoggedProcess.cpp b/libraries/logic/launch/LoggedProcess.cpp
new file mode 100644
index 00000000..88ca40aa
--- /dev/null
+++ b/libraries/logic/launch/LoggedProcess.cpp
@@ -0,0 +1,163 @@
+#include "LoggedProcess.h"
+#include "MessageLevel.h"
+#include <QDebug>
+
+LoggedProcess::LoggedProcess(QObject *parent) : QProcess(parent)
+{
+	// QProcess has a strange interface... let's map a lot of those into a few.
+	connect(this, &QProcess::readyReadStandardOutput, this, &LoggedProcess::on_stdOut);
+	connect(this, &QProcess::readyReadStandardError, this, &LoggedProcess::on_stdErr);
+	connect(this, SIGNAL(finished(int,QProcess::ExitStatus)), SLOT(on_exit(int,QProcess::ExitStatus)));
+	connect(this, SIGNAL(error(QProcess::ProcessError)), this, SLOT(on_error(QProcess::ProcessError)));
+	connect(this, &QProcess::stateChanged, this, &LoggedProcess::on_stateChange);
+}
+
+QStringList reprocess(const QByteArray & data, QString & leftover)
+{
+	QString str = leftover + QString::fromLocal8Bit(data);
+
+	str.remove('\r');
+	QStringList lines = str.split("\n");
+	leftover = lines.takeLast();
+	return lines;
+}
+
+void LoggedProcess::on_stdErr()
+{
+	auto lines = reprocess(readAllStandardError(), m_err_leftover);
+	emit log(lines, MessageLevel::StdErr);
+}
+
+void LoggedProcess::on_stdOut()
+{
+	auto lines = reprocess(readAllStandardOutput(), m_out_leftover);
+	emit log(lines, MessageLevel::StdOut);
+}
+
+void LoggedProcess::on_exit(int exit_code, QProcess::ExitStatus status)
+{
+	// save the exit code
+	m_exit_code = exit_code;
+
+	// Flush console window
+	if (!m_err_leftover.isEmpty())
+	{
+		emit log({m_err_leftover}, MessageLevel::StdErr);
+		m_err_leftover.clear();
+	}
+	if (!m_out_leftover.isEmpty())
+	{
+		emit log({m_err_leftover}, MessageLevel::StdOut);
+		m_out_leftover.clear();
+	}
+
+	// based on state, send signals
+	if (!m_is_aborting)
+	{
+		if (status == QProcess::NormalExit)
+		{
+			//: Message displayed on instance exit
+			emit log({tr("Process exited with code %1.").arg(exit_code)}, MessageLevel::MultiMC);
+			changeState(LoggedProcess::Finished);
+		}
+		else
+		{
+			//: Message displayed on instance crashed
+			if(exit_code == -1)
+				emit log({tr("Process crashed.")}, MessageLevel::MultiMC);
+			else
+				emit log({tr("Process crashed with exitcode %1.").arg(exit_code)}, MessageLevel::MultiMC);
+			changeState(LoggedProcess::Crashed);
+		}
+	}
+	else
+	{
+		//: Message displayed after the instance exits due to kill request
+		emit log({tr("Process was killed by user.")}, MessageLevel::Error);
+		changeState(LoggedProcess::Aborted);
+	}
+}
+
+void LoggedProcess::on_error(QProcess::ProcessError error)
+{
+	switch(error)
+	{
+		case QProcess::FailedToStart:
+		{
+			emit log({tr("The process failed to start.")}, MessageLevel::Fatal);
+			changeState(LoggedProcess::FailedToStart);
+			break;
+		}
+		// we'll just ignore those... never needed them
+		case QProcess::Crashed:
+		case QProcess::ReadError:
+		case QProcess::Timedout:
+		case QProcess::UnknownError:
+		case QProcess::WriteError:
+			break;
+	}
+}
+
+void LoggedProcess::kill()
+{
+	m_is_aborting = true;
+	QProcess::kill();
+}
+
+int LoggedProcess::exitCode() const
+{
+	return m_exit_code;
+}
+
+void LoggedProcess::changeState(LoggedProcess::State state)
+{
+	if(state == m_state)
+		return;
+	m_state = state;
+	emit stateChanged(m_state);
+}
+
+LoggedProcess::State LoggedProcess::state() const
+{
+	return m_state;
+}
+
+void LoggedProcess::on_stateChange(QProcess::ProcessState state)
+{
+	switch(state)
+	{
+		case QProcess::NotRunning:
+			break; // let's not - there are too many that handle this already.
+		case QProcess::Starting:
+		{
+			if(m_state != LoggedProcess::NotRunning)
+			{
+				qWarning() << "Wrong state change for process from state" << m_state << "to" << (int) LoggedProcess::Starting;
+			}
+			changeState(LoggedProcess::Starting);
+			return;
+		}
+		case QProcess::Running:
+		{
+			if(m_state != LoggedProcess::Starting)
+			{
+				qWarning() << "Wrong state change for process from state" << m_state << "to" << (int) LoggedProcess::Running;
+			}
+			changeState(LoggedProcess::Running);
+			return;
+		}
+	}
+}
+
+#if defined Q_OS_WIN32
+#include <windows.h>
+#endif
+
+qint64 LoggedProcess::processId() const
+{
+#ifdef Q_OS_WIN
+    return pid() ? pid()->dwProcessId : 0;
+#else
+    return pid();
+#endif
+}
diff --git a/libraries/logic/launch/LoggedProcess.h b/libraries/logic/launch/LoggedProcess.h
new file mode 100644
index 00000000..baa53d79
--- /dev/null
+++ b/libraries/logic/launch/LoggedProcess.h
@@ -0,0 +1,76 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QProcess>
+#include "MessageLevel.h"
+
+/*
+ * This is a basic process.
+ * It has line-based logging support and hides some of the nasty bits.
+ */
+class LoggedProcess : public QProcess
+{
+Q_OBJECT
+public:
+	enum State
+	{
+		NotRunning,
+		Starting,
+		FailedToStart,
+		Running,
+		Finished,
+		Crashed,
+		Aborted
+	};
+
+public:
+    explicit LoggedProcess(QObject* parent = 0);
+    virtual ~LoggedProcess() {};
+
+	State state() const;
+	int exitCode() const;
+	qint64 processId() const;
+
+signals:
+	void log(QStringList lines, MessageLevel::Enum level);
+	void stateChanged(LoggedProcess::State state);
+
+public slots:
+	/**
+	 * @brief kill the process - equivalent to kill -9
+	 */
+	void kill();
+
+
+private slots:
+	void on_stdErr();
+	void on_stdOut();
+	void on_exit(int exit_code, QProcess::ExitStatus status);
+	void on_error(QProcess::ProcessError error);
+	void on_stateChange(QProcess::ProcessState);
+
+private:
+	void changeState(LoggedProcess::State state);
+
+private:
+	QString m_err_leftover;
+	QString m_out_leftover;
+	bool m_killed = false;
+	State m_state = NotRunning;
+	int m_exit_code = 0;
+	bool m_is_aborting = false;
+};
diff --git a/libraries/logic/launch/MessageLevel.cpp b/libraries/logic/launch/MessageLevel.cpp
new file mode 100644
index 00000000..a5191290
--- /dev/null
+++ b/libraries/logic/launch/MessageLevel.cpp
@@ -0,0 +1,36 @@
+#include "MessageLevel.h"
+
+MessageLevel::Enum MessageLevel::getLevel(const QString& levelName)
+{
+	if (levelName == "MultiMC")
+		return MessageLevel::MultiMC;
+	else if (levelName == "Debug")
+		return MessageLevel::Debug;
+	else if (levelName == "Info")
+		return MessageLevel::Info;
+	else if (levelName == "Message")
+		return MessageLevel::Message;
+	else if (levelName == "Warning")
+		return MessageLevel::Warning;
+	else if (levelName == "Error")
+		return MessageLevel::Error;
+	else if (levelName == "Fatal")
+		return MessageLevel::Fatal;
+	// Skip PrePost, it's not exposed to !![]!
+	// Also skip StdErr and StdOut
+	else
+		return MessageLevel::Unknown;
+}
+
+MessageLevel::Enum MessageLevel::fromLine(QString &line)
+{
+	// Level prefix
+	int endmark = line.indexOf("]!");
+	if (line.startsWith("!![") && endmark != -1)
+	{
+		auto level = MessageLevel::getLevel(line.left(endmark).mid(3));
+		line = line.mid(endmark + 2);
+		return level;
+	}
+	return MessageLevel::Unknown;
+}
diff --git a/libraries/logic/launch/MessageLevel.h b/libraries/logic/launch/MessageLevel.h
new file mode 100644
index 00000000..0128148d
--- /dev/null
+++ b/libraries/logic/launch/MessageLevel.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <QString>
+
+/**
+ * @brief the MessageLevel Enum
+ * defines what level a log message is
+ */
+namespace MessageLevel
+{
+enum Enum
+{
+	Unknown, /**< No idea what this is or where it came from */
+	StdOut,  /**< Undetermined stderr messages */
+	StdErr,  /**< Undetermined stdout messages */
+	MultiMC, /**< MultiMC Messages */
+	Debug,   /**< Debug Messages */
+	Info,    /**< Info Messages */
+	Message, /**< Standard Messages */
+	Warning, /**< Warnings */
+	Error,   /**< Errors */
+	Fatal,   /**< Fatal Errors */
+};
+MessageLevel::Enum getLevel(const QString &levelName);
+
+/* Get message level from a line. Line is modified if it was successful. */
+MessageLevel::Enum fromLine(QString &line);
+}
diff --git a/libraries/logic/launch/steps/CheckJava.cpp b/libraries/logic/launch/steps/CheckJava.cpp
new file mode 100644
index 00000000..a4eaa307
--- /dev/null
+++ b/libraries/logic/launch/steps/CheckJava.cpp
@@ -0,0 +1,92 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "CheckJava.h"
+#include <launch/LaunchTask.h>
+#include <FileSystem.h>
+#include <QStandardPaths>
+#include <QFileInfo>
+
+void CheckJava::executeTask()
+{
+	auto instance = m_parent->instance();
+	auto settings = instance->settings();
+	m_javaPath = FS::ResolveExecutable(settings->get("JavaPath").toString());
+	bool perInstance = settings->get("OverrideJava").toBool() || settings->get("OverrideJavaLocation").toBool();
+
+	auto realJavaPath = QStandardPaths::findExecutable(m_javaPath);
+	if (realJavaPath.isEmpty())
+	{
+		if (perInstance)
+		{
+			emit logLine(
+				tr("The java binary \"%1\" couldn't be found. Please fix the java path "
+				   "override in the instance's settings or disable it.").arg(m_javaPath),
+				MessageLevel::Warning);
+		}
+		else
+		{
+			emit logLine(tr("The java binary \"%1\" couldn't be found. Please set up java in "
+							"the settings.").arg(m_javaPath),
+						 MessageLevel::Warning);
+		}
+		emitFailed(tr("Java path is not valid."));
+		return;
+	}
+	else
+	{
+		emit logLine("Java path is:\n" + m_javaPath + "\n\n", MessageLevel::MultiMC);
+	}
+
+	QFileInfo javaInfo(realJavaPath);
+	qlonglong javaUnixTime = javaInfo.lastModified().toMSecsSinceEpoch();
+	auto storedUnixTime = settings->get("JavaTimestamp").toLongLong();
+	m_javaUnixTime = javaUnixTime;
+	// if they are not the same, check!
+	if (javaUnixTime != storedUnixTime)
+	{
+		m_JavaChecker = std::make_shared<JavaChecker>();
+		QString errorLog;
+		QString version;
+		emit logLine(tr("Checking Java version..."), MessageLevel::MultiMC);
+		connect(m_JavaChecker.get(), &JavaChecker::checkFinished, this,
+				&CheckJava::checkJavaFinished);
+		m_JavaChecker->m_path = realJavaPath;
+		m_JavaChecker->performCheck();
+		return;
+	}
+	emitSucceeded();
+}
+
+void CheckJava::checkJavaFinished(JavaCheckResult result)
+{
+	if (!result.valid)
+	{
+		// Error message displayed if java can't start
+		emit logLine(tr("Could not start java:"), MessageLevel::Error);
+		emit logLines(result.errorLog.split('\n'), MessageLevel::Error);
+		emit logLine("\nCheck your MultiMC Java settings.", MessageLevel::MultiMC);
+		emitFailed(tr("Could not start java!"));
+	}
+	else
+	{
+		auto instance = m_parent->instance();
+		emit logLine(tr("Java version is %1!\n").arg(result.javaVersion.toString()),
+					 MessageLevel::MultiMC);
+		instance->settings()->set("JavaVersion", result.javaVersion.toString());
+		instance->settings()->set("JavaTimestamp", m_javaUnixTime);
+		emitSucceeded();
+	}
+}
diff --git a/libraries/logic/launch/steps/CheckJava.h b/libraries/logic/launch/steps/CheckJava.h
new file mode 100644
index 00000000..b63dd4f4
--- /dev/null
+++ b/libraries/logic/launch/steps/CheckJava.h
@@ -0,0 +1,41 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <launch/LoggedProcess.h>
+#include <java/JavaChecker.h>
+
+class CheckJava: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit CheckJava(LaunchTask *parent) :LaunchStep(parent){};
+	virtual ~CheckJava() {};
+
+	virtual void executeTask();
+	virtual bool canAbort() const
+	{
+		return false;
+	}
+private slots:
+	void checkJavaFinished(JavaCheckResult result);
+
+private:
+	QString m_javaPath;
+	qlonglong m_javaUnixTime;
+	JavaCheckerPtr m_JavaChecker;
+};
diff --git a/libraries/logic/launch/steps/LaunchMinecraft.cpp b/libraries/logic/launch/steps/LaunchMinecraft.cpp
new file mode 100644
index 00000000..77a89f17
--- /dev/null
+++ b/libraries/logic/launch/steps/LaunchMinecraft.cpp
@@ -0,0 +1,154 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LaunchMinecraft.h"
+#include <launch/LaunchTask.h>
+#include <minecraft/MinecraftInstance.h>
+#include <FileSystem.h>
+#include <QStandardPaths>
+
+LaunchMinecraft::LaunchMinecraft(LaunchTask *parent) : LaunchStep(parent)
+{
+	connect(&m_process, &LoggedProcess::log, this, &LaunchMinecraft::logLines);
+	connect(&m_process, &LoggedProcess::stateChanged, this, &LaunchMinecraft::on_state);
+}
+
+void LaunchMinecraft::executeTask()
+{
+	auto instance = m_parent->instance();
+	std::shared_ptr<MinecraftInstance> minecraftInstance = std::dynamic_pointer_cast<MinecraftInstance>(instance);
+
+	m_launchScript = minecraftInstance->createLaunchScript(m_session);
+
+	QStringList args = minecraftInstance->javaArguments();
+
+	// HACK: this is a workaround for MCL-3732 - 'server-resource-packs' is created.
+	if(!FS::ensureFolderPathExists(FS::PathCombine(minecraftInstance->minecraftRoot(), "server-resource-packs")))
+	{
+		emit logLine(tr("Couldn't create the 'server-resource-packs' folder"), MessageLevel::Error);
+	}
+
+	QString allArgs = args.join(", ");
+	emit logLine("Java Arguments:\n[" + m_parent->censorPrivateInfo(allArgs) + "]\n\n", MessageLevel::MultiMC);
+
+	auto javaPath = FS::ResolveExecutable(instance->settings()->get("JavaPath").toString());
+
+	m_process.setProcessEnvironment(instance->createEnvironment());
+
+	QString wrapperCommand = instance->getWrapperCommand();
+	if(!wrapperCommand.isEmpty())
+	{
+		auto realWrapperCommand = QStandardPaths::findExecutable(wrapperCommand);
+		if (realWrapperCommand.isEmpty())
+		{
+			QString reason = tr("The wrapper command \"%1\" couldn't be found.").arg(wrapperCommand);
+			emit logLine(reason, MessageLevel::Fatal);
+			emitFailed(reason);
+			return;
+		}
+		emit logLine("Wrapper command is:\n" + wrapperCommand + "\n\n", MessageLevel::MultiMC);
+		args.prepend(javaPath);
+		m_process.start(wrapperCommand, args);
+	}
+	else
+	{
+		m_process.start(javaPath, args);
+	}
+}
+
+void LaunchMinecraft::on_state(LoggedProcess::State state)
+{
+	switch(state)
+	{
+		case LoggedProcess::FailedToStart:
+		{
+			//: Error message displayed if instace can't start
+			QString reason = tr("Could not launch minecraft!");
+			emit logLine(reason, MessageLevel::Fatal);
+			emitFailed(reason);
+			return;
+		}
+		case LoggedProcess::Aborted:
+		case LoggedProcess::Crashed:
+
+		{
+			m_parent->setPid(-1);
+			emitFailed("Game crashed.");
+			return;
+		}
+		case LoggedProcess::Finished:
+		{
+			m_parent->setPid(-1);
+			// if the exit code wasn't 0, report this as a crash
+			auto exitCode = m_process.exitCode();
+			if(exitCode != 0)
+			{
+				emitFailed("Game crashed.");
+				return;
+			}
+			//FIXME: make this work again
+			// m_postlaunchprocess.processEnvironment().insert("INST_EXITCODE", QString(exitCode));
+			// run post-exit
+			emitSucceeded();
+			break;
+		}
+		case LoggedProcess::Running:
+			emit logLine(tr("Minecraft process ID: %1\n\n").arg(m_process.processId()), MessageLevel::MultiMC);
+			m_parent->setPid(m_process.processId());
+			m_parent->instance()->setLastLaunch();
+			// send the launch script to the launcher part
+			m_process.write(m_launchScript.toUtf8());
+
+			mayProceed = true;
+			emit readyForLaunch();
+			break;
+		default:
+			break;
+	}
+}
+
+void LaunchMinecraft::setWorkingDirectory(const QString &wd)
+{
+	m_process.setWorkingDirectory(wd);
+}
+
+void LaunchMinecraft::proceed()
+{
+	if(mayProceed)
+	{
+		QString launchString("launch\n");
+		m_process.write(launchString.toUtf8());
+		mayProceed = false;
+	}
+}
+
+bool LaunchMinecraft::abort()
+{
+	if(mayProceed)
+	{
+		mayProceed = false;
+		QString launchString("abort\n");
+		m_process.write(launchString.toUtf8());
+	}
+	else
+	{
+		auto state = m_process.state();
+		if (state == LoggedProcess::Running || state == LoggedProcess::Starting)
+		{
+			m_process.kill();
+		}
+	}
+	return true;
+}
diff --git a/libraries/logic/launch/steps/LaunchMinecraft.h b/libraries/logic/launch/steps/LaunchMinecraft.h
new file mode 100644
index 00000000..6b9f7919
--- /dev/null
+++ b/libraries/logic/launch/steps/LaunchMinecraft.h
@@ -0,0 +1,48 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <launch/LoggedProcess.h>
+#include <minecraft/auth/AuthSession.h>
+
+class LaunchMinecraft: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit LaunchMinecraft(LaunchTask *parent);
+	virtual void executeTask();
+	virtual bool abort();
+	virtual void proceed();
+	virtual bool canAbort() const
+	{
+		return true;
+	}
+	void setWorkingDirectory(const QString &wd);
+	void setAuthSession(AuthSessionPtr session)
+	{
+		m_session = session;
+	}
+private slots:
+	void on_state(LoggedProcess::State state);
+
+private:
+	LoggedProcess m_process;
+	QString m_command;
+	QString m_launchScript;
+	AuthSessionPtr m_session;
+	bool mayProceed = false;
+};
diff --git a/libraries/logic/launch/steps/ModMinecraftJar.cpp b/libraries/logic/launch/steps/ModMinecraftJar.cpp
new file mode 100644
index 00000000..fce2d70a
--- /dev/null
+++ b/libraries/logic/launch/steps/ModMinecraftJar.cpp
@@ -0,0 +1,44 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ModMinecraftJar.h"
+#include <launch/LaunchTask.h>
+#include <QStandardPaths>
+
+void ModMinecraftJar::executeTask()
+{
+	m_jarModTask = m_parent->instance()->createJarModdingTask();
+	if(m_jarModTask)
+	{
+		connect(m_jarModTask.get(), SIGNAL(finished()), this, SLOT(jarModdingFinished()));
+		m_jarModTask->start();
+		return;
+	}
+	emitSucceeded();
+}
+
+void ModMinecraftJar::jarModdingFinished()
+{
+	if(m_jarModTask->successful())
+	{
+		emitSucceeded();
+	}
+	else
+	{
+		QString reason = tr("jar modding failed because: %1.\n\n").arg(m_jarModTask->failReason());
+		emit logLine(reason, MessageLevel::Fatal);
+		emitFailed(reason);
+	}
+}
diff --git a/libraries/logic/launch/steps/ModMinecraftJar.h b/libraries/logic/launch/steps/ModMinecraftJar.h
new file mode 100644
index 00000000..b35dfafa
--- /dev/null
+++ b/libraries/logic/launch/steps/ModMinecraftJar.h
@@ -0,0 +1,39 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <memory>
+
+// FIXME: temporary wrapper for existing task.
+class ModMinecraftJar: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit ModMinecraftJar(LaunchTask *parent) : LaunchStep(parent) {};
+	virtual ~ModMinecraftJar(){};
+
+	virtual void executeTask();
+	virtual bool canAbort() const
+	{
+		return false;
+	}
+private slots:
+	void jarModdingFinished();
+
+private:
+	std::shared_ptr<Task> m_jarModTask;
+};
diff --git a/libraries/logic/launch/steps/PostLaunchCommand.cpp b/libraries/logic/launch/steps/PostLaunchCommand.cpp
new file mode 100644
index 00000000..29a45f1b
--- /dev/null
+++ b/libraries/logic/launch/steps/PostLaunchCommand.cpp
@@ -0,0 +1,84 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "PostLaunchCommand.h"
+#include <launch/LaunchTask.h>
+
+PostLaunchCommand::PostLaunchCommand(LaunchTask *parent) : LaunchStep(parent)
+{
+	auto instance = m_parent->instance();
+	m_command = instance->getPostExitCommand();
+	m_process.setProcessEnvironment(instance->createEnvironment());
+	connect(&m_process, &LoggedProcess::log, this, &PostLaunchCommand::logLines);
+	connect(&m_process, &LoggedProcess::stateChanged, this, &PostLaunchCommand::on_state);
+}
+
+void PostLaunchCommand::executeTask()
+{
+	QString postlaunch_cmd = m_parent->substituteVariables(m_command);
+	emit logLine(tr("Running Post-Launch command: %1").arg(postlaunch_cmd), MessageLevel::MultiMC);
+	m_process.start(postlaunch_cmd);
+}
+
+void PostLaunchCommand::on_state(LoggedProcess::State state)
+{
+	auto getError = [&]()
+	{
+		return tr("Post-Launch command failed with code %1.\n\n").arg(m_process.exitCode());
+	};
+	switch(state)
+	{
+		case LoggedProcess::Aborted:
+		case LoggedProcess::Crashed:
+		case LoggedProcess::FailedToStart:
+		{
+			auto error = getError();
+			emit logLine(error, MessageLevel::Fatal);
+			emitFailed(error);
+			return;
+		}
+		case LoggedProcess::Finished:
+		{
+			if(m_process.exitCode() != 0)
+			{
+				auto error = getError();
+				emit logLine(error, MessageLevel::Fatal);
+				emitFailed(error);
+			}
+			else
+			{
+				emit logLine(tr("Post-Launch command ran successfully.\n\n"), MessageLevel::MultiMC);
+				emitSucceeded();
+			}
+		}
+		default:
+			break;
+	}
+}
+
+void PostLaunchCommand::setWorkingDirectory(const QString &wd)
+{
+	m_process.setWorkingDirectory(wd);
+}
+
+bool PostLaunchCommand::abort()
+{
+	auto state = m_process.state();
+	if (state == LoggedProcess::Running || state == LoggedProcess::Starting)
+	{
+		m_process.kill();
+	}
+	return true;
+}
diff --git a/libraries/logic/launch/steps/PostLaunchCommand.h b/libraries/logic/launch/steps/PostLaunchCommand.h
new file mode 100644
index 00000000..4d5b0a52
--- /dev/null
+++ b/libraries/logic/launch/steps/PostLaunchCommand.h
@@ -0,0 +1,39 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <launch/LoggedProcess.h>
+
+class PostLaunchCommand: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit PostLaunchCommand(LaunchTask *parent);
+	virtual void executeTask();
+	virtual bool abort();
+	virtual bool canAbort() const
+	{
+		return true;
+	}
+	void setWorkingDirectory(const QString &wd);
+private slots:
+	void on_state(LoggedProcess::State state);
+
+private:
+	LoggedProcess m_process;
+	QString m_command;
+};
diff --git a/libraries/logic/launch/steps/PreLaunchCommand.cpp b/libraries/logic/launch/steps/PreLaunchCommand.cpp
new file mode 100644
index 00000000..47197a82
--- /dev/null
+++ b/libraries/logic/launch/steps/PreLaunchCommand.cpp
@@ -0,0 +1,85 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "PreLaunchCommand.h"
+#include <launch/LaunchTask.h>
+
+PreLaunchCommand::PreLaunchCommand(LaunchTask *parent) : LaunchStep(parent)
+{
+	auto instance = m_parent->instance();
+	m_command = instance->getPreLaunchCommand();
+	m_process.setProcessEnvironment(instance->createEnvironment());
+	connect(&m_process, &LoggedProcess::log, this, &PreLaunchCommand::logLines);
+	connect(&m_process, &LoggedProcess::stateChanged, this, &PreLaunchCommand::on_state);
+}
+
+void PreLaunchCommand::executeTask()
+{
+	//FIXME: where to put this?
+	QString prelaunch_cmd = m_parent->substituteVariables(m_command);
+	emit logLine(tr("Running Pre-Launch command: %1").arg(prelaunch_cmd), MessageLevel::MultiMC);
+	m_process.start(prelaunch_cmd);
+}
+
+void PreLaunchCommand::on_state(LoggedProcess::State state)
+{
+	auto getError = [&]()
+	{
+		return tr("Pre-Launch command failed with code %1.\n\n").arg(m_process.exitCode());
+	};
+	switch(state)
+	{
+		case LoggedProcess::Aborted:
+		case LoggedProcess::Crashed:
+		case LoggedProcess::FailedToStart:
+		{
+			auto error = getError();
+			emit logLine(error, MessageLevel::Fatal);
+			emitFailed(error);
+			return;
+		}
+		case LoggedProcess::Finished:
+		{
+			if(m_process.exitCode() != 0)
+			{
+				auto error = getError();
+				emit logLine(error, MessageLevel::Fatal);
+				emitFailed(error);
+			}
+			else
+			{
+				emit logLine(tr("Pre-Launch command ran successfully.\n\n"), MessageLevel::MultiMC);
+				emitSucceeded();
+			}
+		}
+		default:
+			break;
+	}
+}
+
+void PreLaunchCommand::setWorkingDirectory(const QString &wd)
+{
+	m_process.setWorkingDirectory(wd);
+}
+
+bool PreLaunchCommand::abort()
+{
+	auto state = m_process.state();
+	if (state == LoggedProcess::Running || state == LoggedProcess::Starting)
+	{
+		m_process.kill();
+	}
+	return true;
+}
diff --git a/libraries/logic/launch/steps/PreLaunchCommand.h b/libraries/logic/launch/steps/PreLaunchCommand.h
new file mode 100644
index 00000000..077bdfca
--- /dev/null
+++ b/libraries/logic/launch/steps/PreLaunchCommand.h
@@ -0,0 +1,39 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <launch/LoggedProcess.h>
+
+class PreLaunchCommand: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit PreLaunchCommand(LaunchTask *parent);
+	virtual void executeTask();
+	virtual bool abort();
+	virtual bool canAbort() const
+	{
+		return true;
+	}
+	void setWorkingDirectory(const QString &wd);
+private slots:
+	void on_state(LoggedProcess::State state);
+
+private:
+	LoggedProcess m_process;
+	QString m_command;
+};
diff --git a/libraries/logic/launch/steps/TextPrint.cpp b/libraries/logic/launch/steps/TextPrint.cpp
new file mode 100644
index 00000000..f307b1fd
--- /dev/null
+++ b/libraries/logic/launch/steps/TextPrint.cpp
@@ -0,0 +1,29 @@
+#include "TextPrint.h"
+
+TextPrint::TextPrint(LaunchTask * parent, const QStringList &lines, MessageLevel::Enum level) : LaunchStep(parent)
+{
+	m_lines = lines;
+	m_level = level;
+}
+TextPrint::TextPrint(LaunchTask *parent, const QString &line, MessageLevel::Enum level) : LaunchStep(parent)
+{
+	m_lines.append(line);
+	m_level = level;
+}
+
+void TextPrint::executeTask()
+{
+	emit logLines(m_lines, m_level);
+	emitSucceeded();
+}
+
+bool TextPrint::canAbort() const
+{
+	return true;
+}
+
+bool TextPrint::abort()
+{
+	emitFailed("Aborted.");
+	return true;
+}
diff --git a/libraries/logic/launch/steps/TextPrint.h b/libraries/logic/launch/steps/TextPrint.h
new file mode 100644
index 00000000..fdd9014a
--- /dev/null
+++ b/libraries/logic/launch/steps/TextPrint.h
@@ -0,0 +1,43 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <launch/LoggedProcess.h>
+#include <java/JavaChecker.h>
+
+#include "multimc_logic_export.h"
+
+/*
+ * FIXME: maybe do not export
+ */
+
+class MULTIMC_LOGIC_EXPORT TextPrint: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit TextPrint(LaunchTask *parent, const QStringList &lines, MessageLevel::Enum level);
+	explicit TextPrint(LaunchTask *parent, const QString &line, MessageLevel::Enum level);
+	virtual ~TextPrint(){};
+
+	virtual void executeTask();
+	virtual bool canAbort() const;
+	virtual bool abort();
+
+private:
+	QStringList m_lines;
+	MessageLevel::Enum m_level;
+};
diff --git a/libraries/logic/launch/steps/Update.cpp b/libraries/logic/launch/steps/Update.cpp
new file mode 100644
index 00000000..4901f001
--- /dev/null
+++ b/libraries/logic/launch/steps/Update.cpp
@@ -0,0 +1,50 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Update.h"
+#include <launch/LaunchTask.h>
+
+void Update::executeTask()
+{
+	m_updateTask = m_parent->instance()->createUpdateTask();
+	if(m_updateTask)
+	{
+		connect(m_updateTask.get(), SIGNAL(finished()), this, SLOT(updateFinished()));
+		connect(m_updateTask.get(), &Task::progress, this, &Task::setProgress);
+		connect(m_updateTask.get(), &Task::status, this, &Task::setStatus);
+		emit progressReportingRequest();
+		return;
+	}
+	emitSucceeded();
+}
+
+void Update::proceed()
+{
+	m_updateTask->start();
+}
+
+void Update::updateFinished()
+{
+	if(m_updateTask->successful())
+	{
+		emitSucceeded();
+	}
+	else
+	{
+		QString reason = tr("Instance update failed because: %1.\n\n").arg(m_updateTask->failReason());
+		emit logLine(reason, MessageLevel::Fatal);
+		emitFailed(reason);
+	}
+}
diff --git a/libraries/logic/launch/steps/Update.h b/libraries/logic/launch/steps/Update.h
new file mode 100644
index 00000000..14928253
--- /dev/null
+++ b/libraries/logic/launch/steps/Update.h
@@ -0,0 +1,41 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <launch/LaunchStep.h>
+#include <launch/LoggedProcess.h>
+#include <java/JavaChecker.h>
+
+// FIXME: stupid. should be defined by the instance type? or even completely abstracted away...
+class Update: public LaunchStep
+{
+	Q_OBJECT
+public:
+	explicit Update(LaunchTask *parent):LaunchStep(parent) {};
+	virtual ~Update() {};
+
+	virtual void executeTask();
+	virtual bool canAbort() const
+	{
+		return false;
+	}
+	virtual void proceed();
+private slots:
+	void updateFinished();
+
+private:
+	std::shared_ptr<Task> m_updateTask;
+};
diff --git a/libraries/logic/minecraft/AssetsUtils.cpp b/libraries/logic/minecraft/AssetsUtils.cpp
new file mode 100644
index 00000000..7a525abe
--- /dev/null
+++ b/libraries/logic/minecraft/AssetsUtils.cpp
@@ -0,0 +1,230 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QFileInfo>
+#include <QDir>
+#include <QDirIterator>
+#include <QCryptographicHash>
+#include <QJsonParseError>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QVariant>
+#include <QDebug>
+
+#include "AssetsUtils.h"
+#include "FileSystem.h"
+#include "net/MD5EtagDownload.h"
+
+namespace AssetsUtils
+{
+
+/*
+ * Returns true on success, with index populated
+ * index is undefined otherwise
+ */
+bool loadAssetsIndexJson(QString assetsId, QString path, AssetsIndex *index)
+{
+	/*
+	{
+	  "objects": {
+		"icons/icon_16x16.png": {
+		  "hash": "bdf48ef6b5d0d23bbb02e17d04865216179f510a",
+		  "size": 3665
+		},
+		...
+		}
+	  }
+	}
+	*/
+
+	QFile file(path);
+
+	// Try to open the file and fail if we can't.
+	// TODO: We should probably report this error to the user.
+	if (!file.open(QIODevice::ReadOnly))
+	{
+		qCritical() << "Failed to read assets index file" << path;
+		return false;
+	}
+	index->id = assetsId;
+
+	// Read the file and close it.
+	QByteArray jsonData = file.readAll();
+	file.close();
+
+	QJsonParseError parseError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &parseError);
+
+	// Fail if the JSON is invalid.
+	if (parseError.error != QJsonParseError::NoError)
+	{
+		qCritical() << "Failed to parse assets index file:" << parseError.errorString()
+					 << "at offset " << QString::number(parseError.offset);
+		return false;
+	}
+
+	// Make sure the root is an object.
+	if (!jsonDoc.isObject())
+	{
+		qCritical() << "Invalid assets index JSON: Root should be an array.";
+		return false;
+	}
+
+	QJsonObject root = jsonDoc.object();
+
+	QJsonValue isVirtual = root.value("virtual");
+	if (!isVirtual.isUndefined())
+	{
+		index->isVirtual = isVirtual.toBool(false);
+	}
+
+	QJsonValue objects = root.value("objects");
+	QVariantMap map = objects.toVariant().toMap();
+
+	for (QVariantMap::const_iterator iter = map.begin(); iter != map.end(); ++iter)
+	{
+		// qDebug() << iter.key();
+
+		QVariant variant = iter.value();
+		QVariantMap nested_objects = variant.toMap();
+
+		AssetObject object;
+
+		for (QVariantMap::const_iterator nested_iter = nested_objects.begin();
+			 nested_iter != nested_objects.end(); ++nested_iter)
+		{
+			// qDebug() << nested_iter.key() << nested_iter.value().toString();
+			QString key = nested_iter.key();
+			QVariant value = nested_iter.value();
+
+			if (key == "hash")
+			{
+				object.hash = value.toString();
+			}
+			else if (key == "size")
+			{
+				object.size = value.toDouble();
+			}
+		}
+
+		index->objects.insert(iter.key(), object);
+	}
+
+	return true;
+}
+
+QDir reconstructAssets(QString assetsId)
+{
+	QDir assetsDir = QDir("assets/");
+	QDir indexDir = QDir(FS::PathCombine(assetsDir.path(), "indexes"));
+	QDir objectDir = QDir(FS::PathCombine(assetsDir.path(), "objects"));
+	QDir virtualDir = QDir(FS::PathCombine(assetsDir.path(), "virtual"));
+
+	QString indexPath = FS::PathCombine(indexDir.path(), assetsId + ".json");
+	QFile indexFile(indexPath);
+	QDir virtualRoot(FS::PathCombine(virtualDir.path(), assetsId));
+
+	if (!indexFile.exists())
+	{
+		qCritical() << "No assets index file" << indexPath << "; can't reconstruct assets";
+		return virtualRoot;
+	}
+
+	qDebug() << "reconstructAssets" << assetsDir.path() << indexDir.path()
+				 << objectDir.path() << virtualDir.path() << virtualRoot.path();
+
+	AssetsIndex index;
+	bool loadAssetsIndex = AssetsUtils::loadAssetsIndexJson(assetsId, indexPath, &index);
+
+	if (loadAssetsIndex && index.isVirtual)
+	{
+		qDebug() << "Reconstructing virtual assets folder at" << virtualRoot.path();
+
+		for (QString map : index.objects.keys())
+		{
+			AssetObject asset_object = index.objects.value(map);
+			QString target_path = FS::PathCombine(virtualRoot.path(), map);
+			QFile target(target_path);
+
+			QString tlk = asset_object.hash.left(2);
+
+			QString original_path = FS::PathCombine(objectDir.path(), tlk, asset_object.hash);
+			QFile original(original_path);
+			if (!original.exists())
+				continue;
+			if (!target.exists())
+			{
+				QFileInfo info(target_path);
+				QDir target_dir = info.dir();
+				// qDebug() << target_dir;
+				if (!target_dir.exists())
+					QDir("").mkpath(target_dir.path());
+
+				bool couldCopy = original.copy(target_path);
+				qDebug() << " Copying" << original_path << "to" << target_path
+							 << QString::number(couldCopy); // << original.errorString();
+			}
+		}
+
+		// TODO: Write last used time to virtualRoot/.lastused
+	}
+
+	return virtualRoot;
+}
+
+}
+
+NetActionPtr AssetObject::getDownloadAction()
+{
+	QFileInfo objectFile(getLocalPath());
+	if ((!objectFile.isFile()) || (objectFile.size() != size))
+	{
+		auto objectDL = MD5EtagDownload::make(getUrl(), objectFile.filePath());
+		objectDL->m_total_progress = size;
+		return objectDL;
+	}
+	return nullptr;
+}
+
+QString AssetObject::getLocalPath()
+{
+	return "assets/objects/" + getRelPath();
+}
+
+QUrl AssetObject::getUrl()
+{
+	return QUrl("http://resources.download.minecraft.net/" + getRelPath());
+}
+
+QString AssetObject::getRelPath()
+{
+	return hash.left(2) + "/" + hash;
+}
+
+NetJobPtr AssetsIndex::getDownloadJob()
+{
+	auto job = new NetJob(QObject::tr("Assets for %1").arg(id));
+	for (auto &object : objects.values())
+	{
+		auto dl = object.getDownloadAction();
+		if(dl)
+		{
+			job->addNetAction(dl);
+		}
+	}
+	if(job->size())
+		return job;
+	return nullptr;
+}
diff --git a/libraries/logic/minecraft/AssetsUtils.h b/libraries/logic/minecraft/AssetsUtils.h
new file mode 100644
index 00000000..90251c2d
--- /dev/null
+++ b/libraries/logic/minecraft/AssetsUtils.h
@@ -0,0 +1,48 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QMap>
+#include "net/NetAction.h"
+#include "net/NetJob.h"
+
+struct AssetObject
+{
+	QString getRelPath();
+	QUrl getUrl();
+	QString getLocalPath();
+	NetActionPtr getDownloadAction();
+
+	QString hash;
+	qint64 size;
+};
+
+struct AssetsIndex
+{
+	NetJobPtr getDownloadJob();
+
+	QString id;
+	QMap<QString, AssetObject> objects;
+	bool isVirtual = false;
+};
+
+namespace AssetsUtils
+{
+bool loadAssetsIndexJson(QString id, QString file, AssetsIndex* index);
+/// Reconstruct a virtual assets folder for the given assets ID and return the folder
+QDir reconstructAssets(QString assetsId);
+}
diff --git a/libraries/logic/minecraft/GradleSpecifier.h b/libraries/logic/minecraft/GradleSpecifier.h
new file mode 100644
index 00000000..18308537
--- /dev/null
+++ b/libraries/logic/minecraft/GradleSpecifier.h
@@ -0,0 +1,129 @@
+#pragma once
+
+#include <QString>
+#include <QStringList>
+#include "DefaultVariable.h"
+
+struct GradleSpecifier
+{
+	GradleSpecifier()
+	{
+		m_valid = false;
+	}
+	GradleSpecifier(QString value)
+	{
+		operator=(value);
+	}
+	GradleSpecifier & operator =(const QString & value)
+	{
+		/*
+		org.gradle.test.classifiers : service : 1.0 : jdk15 @ jar
+		DEBUG   0 "org.gradle.test.classifiers:service:1.0:jdk15@jar" 
+		DEBUG   1 "org.gradle.test.classifiers" 
+		DEBUG   2 "service" 
+		DEBUG   3 "1.0" 
+		DEBUG   4 ":jdk15" 
+		DEBUG   5 "jdk15" 
+		DEBUG   6 "@jar" 
+		DEBUG   7 "jar"
+		*/
+		QRegExp matcher("([^:@]+):([^:@]+):([^:@]+)" "(:([^:@]+))?" "(@([^:@]+))?");
+		m_valid = matcher.exactMatch(value);
+		auto elements = matcher.capturedTexts();
+		m_groupId = elements[1];
+		m_artifactId = elements[2];
+		m_version = elements[3];
+		m_classifier = elements[5];
+		if(!elements[7].isEmpty())
+		{
+			m_extension = elements[7];
+		}
+		return *this;
+	}
+	operator QString() const
+	{
+		if(!m_valid)
+			return "INVALID";
+		QString retval = m_groupId + ":" + m_artifactId + ":" + m_version;
+		if(!m_classifier.isEmpty())
+		{
+			retval += ":" + m_classifier;
+		}
+		if(m_extension.isExplicit())
+		{
+			retval += "@" + m_extension;
+		}
+		return retval;
+	}
+	QString toPath() const
+	{
+		if(!m_valid)
+			return "INVALID";
+		QString path = m_groupId;
+		path.replace('.', '/');
+		path += '/' + m_artifactId + '/' + m_version + '/' + m_artifactId + '-' + m_version;
+		if(!m_classifier.isEmpty())
+		{
+			path += "-" + m_classifier;
+		}
+		path += "." + m_extension;
+		return path;
+	}
+	inline bool valid() const
+	{
+		return m_valid;
+	}
+	inline QString version() const
+	{
+		return m_version;
+	}
+	inline QString groupId() const
+	{
+		return m_groupId;
+	}
+	inline QString artifactId() const
+	{
+		return m_artifactId;
+	}
+	inline void setClassifier(const QString & classifier)
+	{
+		m_classifier = classifier;
+	}
+	inline QString classifier() const
+	{
+		return m_classifier;
+	}
+	inline QString extension() const
+	{
+		return m_extension;
+	}
+	inline QString artifactPrefix() const
+	{
+		return m_groupId + ":" + m_artifactId;
+	}
+	bool matchName(const GradleSpecifier & other) const
+	{
+		return other.artifactId() == artifactId() && other.groupId() == groupId();
+	}
+	bool operator==(const GradleSpecifier & other) const
+	{
+		if(m_groupId != other.m_groupId)
+			return false;
+		if(m_artifactId != other.m_artifactId)
+			return false;
+		if(m_version != other.m_version)
+			return false;
+		if(m_classifier != other.m_classifier)
+			return false;
+		if(m_extension != other.m_extension)
+			return false;
+		return true;
+	}
+private:
+	QString m_groupId;
+	QString m_artifactId;
+	QString m_version;
+	QString m_classifier;
+	DefaultVariable<QString> m_extension = DefaultVariable<QString>("jar");
+	bool m_valid = false;
+};
diff --git a/libraries/logic/minecraft/JarMod.h b/libraries/logic/minecraft/JarMod.h
new file mode 100644
index 00000000..42d05da9
--- /dev/null
+++ b/libraries/logic/minecraft/JarMod.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <QString>
+#include <QJsonObject>
+#include <memory>
+class Jarmod;
+typedef std::shared_ptr<Jarmod> JarmodPtr;
+class Jarmod
+{
+public: /* data */
+	QString name;
+	QString originalName;
+};
diff --git a/libraries/logic/minecraft/Library.cpp b/libraries/logic/minecraft/Library.cpp
new file mode 100644
index 00000000..922db84e
--- /dev/null
+++ b/libraries/logic/minecraft/Library.cpp
@@ -0,0 +1,239 @@
+#include "Library.h"
+#include <net/CacheDownload.h>
+#include <minecraft/forge/ForgeXzDownload.h>
+#include <Env.h>
+#include <FileSystem.h>
+
+void Library::getApplicableFiles(OpSys system, QStringList& jar, QStringList& native, QStringList& native32, QStringList& native64) const
+{
+	auto actualPath = [&](QString relPath)
+	{
+		QFileInfo out(FS::PathCombine(storagePrefix(), relPath));
+		return out.absoluteFilePath();
+	};
+	if(m_mojangDownloads)
+	{
+		if(m_mojangDownloads->artifact)
+		{
+			auto artifact = m_mojangDownloads->artifact;
+			jar += actualPath(artifact->path);
+		}
+		if(!isNative())
+			return;
+		if(m_nativeClassifiers.contains(system))
+		{
+			auto nativeClassifier = m_nativeClassifiers[system];
+			if(nativeClassifier.contains("${arch}"))
+			{
+				auto nat32Classifier = nativeClassifier;
+				nat32Classifier.replace("${arch}", "32");
+				auto nat64Classifier = nativeClassifier;
+				nat64Classifier.replace("${arch}", "64");
+				auto nat32info = m_mojangDownloads->getDownloadInfo(nat32Classifier);
+				if(nat32info)
+					native32 += actualPath(nat32info->path);
+				auto nat64info = m_mojangDownloads->getDownloadInfo(nat64Classifier);
+				if(nat64info)
+					native64 += actualPath(nat64info->path);
+			}
+			else
+			{
+				native += actualPath(m_mojangDownloads->getDownloadInfo(nativeClassifier)->path);
+			}
+		}
+	}
+	else
+	{
+		QString raw_storage = storageSuffix(system);
+		if(isNative())
+		{
+			if (raw_storage.contains("${arch}"))
+			{
+				auto nat32Storage = raw_storage;
+				nat32Storage.replace("${arch}", "32");
+				auto nat64Storage = raw_storage;
+				nat64Storage.replace("${arch}", "64");
+				native32 += actualPath(nat32Storage);
+				native64 += actualPath(nat64Storage);
+			}
+			else
+			{
+				native += actualPath(raw_storage);
+			}
+		}
+		else
+		{
+			jar += actualPath(raw_storage);
+		}
+	}
+}
+
+QList<NetActionPtr> Library::getDownloads(OpSys system, HttpMetaCache * cache, QStringList &failedFiles) const
+{
+	QList<NetActionPtr> out;
+	bool isLocal = (hint() == "local");
+	bool isForge = (hint() == "forge-pack-xz");
+
+	auto add_download = [&](QString storage, QString dl)
+	{
+		auto entry = cache->resolveEntry("libraries", storage);
+		if (!entry->isStale())
+			return true;
+		if(isLocal)
+		{
+			QFileInfo fileinfo(entry->getFullPath());
+			if(!fileinfo.exists())
+			{
+				failedFiles.append(entry->getFullPath());
+				return false;
+			}
+			return true;
+		}
+		if (isForge)
+		{
+			out.append(ForgeXzDownload::make(storage, entry));
+		}
+		else
+		{
+			out.append(CacheDownload::make(dl, entry));
+		}
+		return true;
+	};
+
+	if(m_mojangDownloads)
+	{
+		if(m_mojangDownloads->artifact)
+		{
+			auto artifact = m_mojangDownloads->artifact;
+			add_download(artifact->path, artifact->url);
+		}
+		if(m_nativeClassifiers.contains(system))
+		{
+			auto nativeClassifier = m_nativeClassifiers[system];
+			if(nativeClassifier.contains("${arch}"))
+			{
+				auto nat32Classifier = nativeClassifier;
+				nat32Classifier.replace("${arch}", "32");
+				auto nat64Classifier = nativeClassifier;
+				nat64Classifier.replace("${arch}", "64");
+				auto nat32info = m_mojangDownloads->getDownloadInfo(nat32Classifier);
+				if(nat32info)
+					add_download(nat32info->path, nat32info->url);
+				auto nat64info = m_mojangDownloads->getDownloadInfo(nat64Classifier);
+				if(nat64info)
+					add_download(nat64info->path, nat64info->url);
+			}
+			else
+			{
+				auto info = m_mojangDownloads->getDownloadInfo(nativeClassifier);
+				if(info)
+				{
+					add_download(info->path, info->url);
+				}
+			}
+		}
+	}
+	else
+	{
+		QString raw_storage = storageSuffix(system);
+		auto raw_dl = [&](){
+			if (!m_absoluteURL.isEmpty())
+			{
+				return m_absoluteURL;
+			}
+
+			if (m_repositoryURL.isEmpty())
+			{
+				return QString("https://" + URLConstants::LIBRARY_BASE) + raw_storage;
+			}
+
+			if(m_repositoryURL.endsWith('/'))
+			{
+				return m_repositoryURL + raw_storage;
+			}
+			else
+			{
+				return m_repositoryURL + QChar('/') + raw_storage;
+			}
+		}();
+		if (raw_storage.contains("${arch}"))
+		{
+			QString cooked_storage = raw_storage;
+			QString cooked_dl = raw_dl;
+			add_download(cooked_storage.replace("${arch}", "32"), cooked_dl.replace("${arch}", "32"));
+			cooked_storage = raw_storage;
+			cooked_dl = raw_dl;
+			add_download(cooked_storage.replace("${arch}", "64"), cooked_dl.replace("${arch}", "64"));
+		}
+		else
+		{
+			add_download(raw_storage, raw_dl);
+		}
+	}
+	return out;
+}
+
+bool Library::isActive() const
+{
+	bool result = true;
+	if (m_rules.empty())
+	{
+		result = true;
+	}
+	else
+	{
+		RuleAction ruleResult = Disallow;
+		for (auto rule : m_rules)
+		{
+			RuleAction temp = rule->apply(this);
+			if (temp != Defer)
+				ruleResult = temp;
+		}
+		result = result && (ruleResult == Allow);
+	}
+	if (isNative())
+	{
+		result = result && m_nativeClassifiers.contains(currentSystem);
+	}
+	return result;
+}
+
+void Library::setStoragePrefix(QString prefix)
+{
+	m_storagePrefix = prefix;
+}
+
+QString Library::defaultStoragePrefix()
+{
+	return "libraries/";
+}
+
+QString Library::storagePrefix() const
+{
+	if(m_storagePrefix.isEmpty())
+	{
+		return defaultStoragePrefix();
+	}
+	return m_storagePrefix;
+}
+
+QString Library::storageSuffix(OpSys system) const
+{
+	// non-native? use only the gradle specifier
+	if (!isNative())
+	{
+		return m_name.toPath();
+	}
+
+	// otherwise native, override classifiers. Mojang HACK!
+	GradleSpecifier nativeSpec = m_name;
+	if (m_nativeClassifiers.contains(system))
+	{
+		nativeSpec.setClassifier(m_nativeClassifiers[system]);
+	}
+	else
+	{
+		nativeSpec.setClassifier("INVALID");
+	}
+	return nativeSpec.toPath();
+}
diff --git a/libraries/logic/minecraft/Library.h b/libraries/logic/minecraft/Library.h
new file mode 100644
index 00000000..fdce93f3
--- /dev/null
+++ b/libraries/logic/minecraft/Library.h
@@ -0,0 +1,184 @@
+#pragma once
+#include <QString>
+#include <net/NetAction.h>
+#include <QPair>
+#include <QList>
+#include <QStringList>
+#include <QMap>
+#include <QDir>
+#include <QUrl>
+#include <memory>
+
+#include "Rule.h"
+#include "minecraft/OpSys.h"
+#include "GradleSpecifier.h"
+#include "net/URLConstants.h"
+#include "MojangDownloadInfo.h"
+
+#include "multimc_logic_export.h"
+
+class Library;
+
+typedef std::shared_ptr<Library> LibraryPtr;
+
+class MULTIMC_LOGIC_EXPORT Library
+{
+	friend class OneSixVersionFormat;
+	friend class MojangVersionFormat;
+	friend class LibraryTest;
+public:
+	Library()
+	{
+	}
+	Library(const QString &name)
+	{
+		m_name = name;
+	}
+	/// limited copy without some data. TODO: why?
+	static LibraryPtr limitedCopy(LibraryPtr base)
+	{
+		auto newlib = std::make_shared<Library>();
+		newlib->m_name = base->m_name;
+		newlib->m_repositoryURL = base->m_repositoryURL;
+		newlib->m_hint = base->m_hint;
+		newlib->m_absoluteURL = base->m_absoluteURL;
+		newlib->m_extractExcludes = base->m_extractExcludes;
+		newlib->m_nativeClassifiers = base->m_nativeClassifiers;
+		newlib->m_rules = base->m_rules;
+		newlib->m_storagePrefix = base->m_storagePrefix;
+		newlib->m_mojangDownloads = base->m_mojangDownloads;
+		return newlib;
+	}
+
+public: /* methods */
+	/// Returns the raw name field
+	const GradleSpecifier & rawName() const
+	{
+		return m_name;
+	}
+
+	void setRawName(const GradleSpecifier & spec)
+	{
+		m_name = spec;
+	}
+
+	void setClassifier(const QString & spec)
+	{
+		m_name.setClassifier(spec);
+	}
+
+	/// returns the full group and artifact prefix
+	QString artifactPrefix() const
+	{
+		return m_name.artifactPrefix();
+	}
+
+	/// get the artifact ID
+	QString artifactId() const
+	{
+		return m_name.artifactId();
+	}
+
+	/// get the artifact version
+	QString version() const
+	{
+		return m_name.version();
+	}
+
+	/// Returns true if the library is native
+	bool isNative() const
+	{
+		return m_nativeClassifiers.size() != 0;
+	}
+
+	void setStoragePrefix(QString prefix = QString());
+
+	/// Set the url base for downloads
+	void setRepositoryURL(const QString &base_url)
+	{
+		m_repositoryURL = base_url;
+	}
+
+	void getApplicableFiles(OpSys system, QStringList & jar, QStringList & native, QStringList & native32, QStringList & native64) const;
+
+	void setAbsoluteUrl(const QString &absolute_url)
+	{
+		m_absoluteURL = absolute_url;
+	}
+
+	void setMojangDownloadInfo(MojangLibraryDownloadInfo::Ptr info)
+	{
+		m_mojangDownloads = info;
+	}
+
+	void setHint(const QString &hint)
+	{
+		m_hint = hint;
+	}
+
+	/// Set the load rules
+	void setRules(QList<std::shared_ptr<Rule>> rules)
+	{
+		m_rules = rules;
+	}
+
+	/// Returns true if the library should be loaded (or extracted, in case of natives)
+	bool isActive() const;
+
+	// Get a list of downloads for this library
+	QList<NetActionPtr> getDownloads(OpSys system, class HttpMetaCache * cache, QStringList &failedFiles) const;
+
+private: /* methods */
+	/// the default storage prefix used by MultiMC
+	static QString defaultStoragePrefix();
+
+	/// Get the prefix - root of the storage to be used
+	QString storagePrefix() const;
+
+	/// Get the relative path where the library should be saved
+	QString storageSuffix(OpSys system) const;
+
+	QString hint() const
+	{
+		return m_hint;
+	}
+
+protected: /* data */
+	/// the basic gradle dependency specifier.
+	GradleSpecifier m_name;
+
+	/// DEPRECATED URL prefix of the maven repo where the file can be downloaded
+	QString m_repositoryURL;
+
+	/// DEPRECATED: MultiMC-specific absolute URL. takes precedence over the implicit maven repo URL, if defined
+	QString m_absoluteURL;
+
+	/**
+	 * MultiMC-specific type hint - modifies how the library is treated
+	 */
+	QString m_hint;
+
+	/**
+	 * storage - by default the local libraries folder in multimc, but could be elsewhere
+	 * MultiMC specific, because of FTB.
+	 */
+	QString m_storagePrefix;
+
+	/// true if the library had an extract/excludes section (even empty)
+	bool m_hasExcludes = false;
+
+	/// a list of files that shouldn't be extracted from the library
+	QStringList m_extractExcludes;
+
+	/// native suffixes per OS
+	QMap<OpSys, QString> m_nativeClassifiers;
+
+	/// true if the library had a rules section (even empty)
+	bool applyRules = false;
+
+	/// rules associated with the library
+	QList<std::shared_ptr<Rule>> m_rules;
+
+	/// MOJANG: container with Mojang style download info
+	MojangLibraryDownloadInfo::Ptr m_mojangDownloads;
+};
diff --git a/libraries/logic/minecraft/MinecraftInstance.cpp b/libraries/logic/minecraft/MinecraftInstance.cpp
new file mode 100644
index 00000000..405ccd26
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftInstance.cpp
@@ -0,0 +1,369 @@
+#include "MinecraftInstance.h"
+#include <settings/Setting.h>
+#include "settings/SettingsObject.h"
+#include "Env.h"
+#include "minecraft/MinecraftVersionList.h"
+#include <MMCStrings.h>
+#include <pathmatcher/RegexpMatcher.h>
+#include <pathmatcher/MultiMatcher.h>
+#include <FileSystem.h>
+#include <java/JavaVersion.h>
+
+#define IBUS "@im=ibus"
+
+// all of this because keeping things compatible with deprecated old settings
+// if either of the settings {a, b} is true, this also resolves to true
+class OrSetting : public Setting
+{
+	Q_OBJECT
+public:
+	OrSetting(QString id, std::shared_ptr<Setting> a, std::shared_ptr<Setting> b)
+	:Setting({id}, false), m_a(a), m_b(b)
+	{
+	}
+	virtual QVariant get() const
+	{
+		bool a = m_a->get().toBool();
+		bool b = m_b->get().toBool();
+		return a || b;
+	}
+	virtual void reset() {}
+	virtual void set(QVariant value) {}
+private:
+	std::shared_ptr<Setting> m_a;
+	std::shared_ptr<Setting> m_b;
+};
+
+MinecraftInstance::MinecraftInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir)
+	: BaseInstance(globalSettings, settings, rootDir)
+{
+	// Java Settings
+	auto javaOverride = m_settings->registerSetting("OverrideJava", false);
+	auto locationOverride = m_settings->registerSetting("OverrideJavaLocation", false);
+	auto argsOverride = m_settings->registerSetting("OverrideJavaArgs", false);
+
+	// combinations
+	auto javaOrLocation = std::make_shared<OrSetting>("JavaOrLocationOverride", javaOverride, locationOverride);
+	auto javaOrArgs = std::make_shared<OrSetting>("JavaOrArgsOverride", javaOverride, argsOverride);
+
+	m_settings->registerOverride(globalSettings->getSetting("JavaPath"), javaOrLocation);
+	m_settings->registerOverride(globalSettings->getSetting("JvmArgs"), javaOrArgs);
+
+	// special!
+	m_settings->registerPassthrough(globalSettings->getSetting("JavaTimestamp"), javaOrLocation);
+	m_settings->registerPassthrough(globalSettings->getSetting("JavaVersion"), javaOrLocation);
+
+	// Window Size
+	auto windowSetting = m_settings->registerSetting("OverrideWindow", false);
+	m_settings->registerOverride(globalSettings->getSetting("LaunchMaximized"), windowSetting);
+	m_settings->registerOverride(globalSettings->getSetting("MinecraftWinWidth"), windowSetting);
+	m_settings->registerOverride(globalSettings->getSetting("MinecraftWinHeight"), windowSetting);
+
+	// Memory
+	auto memorySetting = m_settings->registerSetting("OverrideMemory", false);
+	m_settings->registerOverride(globalSettings->getSetting("MinMemAlloc"), memorySetting);
+	m_settings->registerOverride(globalSettings->getSetting("MaxMemAlloc"), memorySetting);
+	m_settings->registerOverride(globalSettings->getSetting("PermGen"), memorySetting);
+}
+
+QString MinecraftInstance::minecraftRoot() const
+{
+	QFileInfo mcDir(FS::PathCombine(instanceRoot(), "minecraft"));
+	QFileInfo dotMCDir(FS::PathCombine(instanceRoot(), ".minecraft"));
+
+	if (dotMCDir.exists() && !mcDir.exists())
+		return dotMCDir.filePath();
+	else
+		return mcDir.filePath();
+}
+
+std::shared_ptr< BaseVersionList > MinecraftInstance::versionList() const
+{
+	return ENV.getVersionList("net.minecraft");
+}
+
+QStringList MinecraftInstance::javaArguments() const
+{
+	QStringList args;
+
+	// custom args go first. we want to override them if we have our own here.
+	args.append(extraArguments());
+
+	// OSX dock icon and name
+#ifdef Q_OS_MAC
+	args << "-Xdock:icon=icon.png";
+	args << QString("-Xdock:name=\"%1\"").arg(windowTitle());
+#endif
+
+	// HACK: Stupid hack for Intel drivers. See: https://mojang.atlassian.net/browse/MCL-767
+#ifdef Q_OS_WIN32
+	args << QString("-XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_"
+					"minecraft.exe.heapdump");
+#endif
+
+	args << QString("-Xms%1m").arg(settings()->get("MinMemAlloc").toInt());
+	args << QString("-Xmx%1m").arg(settings()->get("MaxMemAlloc").toInt());
+
+	// No PermGen in newer java.
+	JavaVersion javaVersion(settings()->get("JavaVersion").toString());
+	if(javaVersion.requiresPermGen())
+	{
+		auto permgen = settings()->get("PermGen").toInt();
+		if (permgen != 64)
+		{
+			args << QString("-XX:PermSize=%1m").arg(permgen);
+		}
+	}
+
+	args << "-Duser.language=en";
+	args << "-jar" << FS::PathCombine(QCoreApplication::applicationDirPath(), "jars", "NewLaunch.jar");
+
+	return args;
+}
+
+QMap<QString, QString> MinecraftInstance::getVariables() const
+{
+	QMap<QString, QString> out;
+	out.insert("INST_NAME", name());
+	out.insert("INST_ID", id());
+	out.insert("INST_DIR", QDir(instanceRoot()).absolutePath());
+	out.insert("INST_MC_DIR", QDir(minecraftRoot()).absolutePath());
+	out.insert("INST_JAVA", settings()->get("JavaPath").toString());
+	out.insert("INST_JAVA_ARGS", javaArguments().join(' '));
+	return out;
+}
+
+static QString processLD_LIBRARY_PATH(const QString & LD_LIBRARY_PATH)
+{
+	QDir mmcBin(QCoreApplication::applicationDirPath());
+	auto items = LD_LIBRARY_PATH.split(':');
+	QStringList final;
+	for(auto & item: items)
+	{
+		QDir test(item);
+		if(test == mmcBin)
+		{
+			qDebug() << "Env:LD_LIBRARY_PATH ignoring path" << item;
+			continue;
+		}
+		final.append(item);
+	}
+	return final.join(':');
+}
+
+QProcessEnvironment MinecraftInstance::createEnvironment()
+{
+	// prepare the process environment
+	QProcessEnvironment rawenv = QProcessEnvironment::systemEnvironment();
+	QProcessEnvironment env;
+
+	QStringList ignored =
+	{
+		"JAVA_ARGS",
+		"CLASSPATH",
+		"CONFIGPATH",
+		"JAVA_HOME",
+		"JRE_HOME",
+		"_JAVA_OPTIONS",
+		"JAVA_OPTIONS",
+		"JAVA_TOOL_OPTIONS"
+	};
+	for(auto key: rawenv.keys())
+	{
+		auto value = rawenv.value(key);
+		// filter out dangerous java crap
+		if(ignored.contains(key))
+		{
+			qDebug() << "Env: ignoring" << key << value;
+			continue;
+		}
+		// filter MultiMC-related things
+		if(key.startsWith("QT_"))
+		{
+			qDebug() << "Env: ignoring" << key << value;
+			continue;
+		}
+#ifdef Q_OS_LINUX
+		// Do not pass LD_* variables to java. They were intended for MultiMC
+		if(key.startsWith("LD_"))
+		{
+			qDebug() << "Env: ignoring" << key << value;
+			continue;
+		}
+		// Strip IBus
+		// IBus is a Linux IME framework. For some reason, it breaks MC?
+		if (key == "XMODIFIERS" && value.contains(IBUS))
+		{
+			QString save = value;
+			value.replace(IBUS, "");
+			qDebug() << "Env: stripped" << IBUS << "from" << save << ":" << value;
+		}
+		if(key == "GAME_PRELOAD")
+		{
+			env.insert("LD_PRELOAD", value);
+			continue;
+		}
+		if(key == "GAME_LIBRARY_PATH")
+		{
+			env.insert("LD_LIBRARY_PATH", processLD_LIBRARY_PATH(value));
+			continue;
+		}
+#endif
+		qDebug() << "Env: " << key << value;
+		env.insert(key, value);
+	}
+#ifdef Q_OS_LINUX
+	// HACK: Workaround for QTBUG42500
+	if(!env.contains("LD_LIBRARY_PATH"))
+	{
+		env.insert("LD_LIBRARY_PATH", "");
+	}
+#endif
+
+	// export some infos
+	auto variables = getVariables();
+	for (auto it = variables.begin(); it != variables.end(); ++it)
+	{
+		env.insert(it.key(), it.value());
+	}
+	return env;
+}
+
+QMap<QString, QString> MinecraftInstance::createCensorFilterFromSession(AuthSessionPtr session)
+{
+	if(!session)
+	{
+		return QMap<QString, QString>();
+	}
+	auto & sessionRef = *session.get();
+	QMap<QString, QString> filter;
+	auto addToFilter = [&filter](QString key, QString value)
+	{
+		if(key.trimmed().size())
+		{
+			filter[key] = value;
+		}
+	};
+	if (sessionRef.session != "-")
+	{
+		addToFilter(sessionRef.session, tr("<SESSION ID>"));
+	}
+	addToFilter(sessionRef.access_token, tr("<ACCESS TOKEN>"));
+	addToFilter(sessionRef.client_token, tr("<CLIENT TOKEN>"));
+	addToFilter(sessionRef.uuid, tr("<PROFILE ID>"));
+	addToFilter(sessionRef.player_name, tr("<PROFILE NAME>"));
+
+	auto i = sessionRef.u.properties.begin();
+	while (i != sessionRef.u.properties.end())
+	{
+		addToFilter(i.value(), "<" + i.key().toUpper() + ">");
+		++i;
+	}
+	return filter;
+}
+
+MessageLevel::Enum MinecraftInstance::guessLevel(const QString &line, MessageLevel::Enum level)
+{
+	QRegularExpression re("\\[(?<timestamp>[0-9:]+)\\] \\[[^/]+/(?<level>[^\\]]+)\\]");
+	auto match = re.match(line);
+	if(match.hasMatch())
+	{
+		// New style logs from log4j
+		QString timestamp = match.captured("timestamp");
+		QString levelStr = match.captured("level");
+		if(levelStr == "INFO")
+			level = MessageLevel::Message;
+		if(levelStr == "WARN")
+			level = MessageLevel::Warning;
+		if(levelStr == "ERROR")
+			level = MessageLevel::Error;
+		if(levelStr == "FATAL")
+			level = MessageLevel::Fatal;
+		if(levelStr == "TRACE" || levelStr == "DEBUG")
+			level = MessageLevel::Debug;
+	}
+	else
+	{
+		// Old style forge logs
+		if (line.contains("[INFO]") || line.contains("[CONFIG]") || line.contains("[FINE]") ||
+			line.contains("[FINER]") || line.contains("[FINEST]"))
+			level = MessageLevel::Message;
+		if (line.contains("[SEVERE]") || line.contains("[STDERR]"))
+			level = MessageLevel::Error;
+		if (line.contains("[WARNING]"))
+			level = MessageLevel::Warning;
+		if (line.contains("[DEBUG]"))
+			level = MessageLevel::Debug;
+	}
+	if (line.contains("overwriting existing"))
+		return MessageLevel::Fatal;
+	//NOTE: this diverges from the real regexp. no unicode, the first section is + instead of *
+	static const QString javaSymbol = "([a-zA-Z_$][a-zA-Z\\d_$]*\\.)+[a-zA-Z_$][a-zA-Z\\d_$]*";
+	if (line.contains("Exception in thread")
+		|| line.contains(QRegularExpression("\\s+at " + javaSymbol))
+		|| line.contains(QRegularExpression("Caused by: " + javaSymbol))
+		|| line.contains(QRegularExpression("([a-zA-Z_$][a-zA-Z\\d_$]*\\.)+[a-zA-Z_$]?[a-zA-Z\\d_$]*(Exception|Error|Throwable)"))
+		|| line.contains(QRegularExpression("... \\d+ more$"))
+		)
+		return MessageLevel::Error;
+	return level;
+}
+
+IPathMatcher::Ptr MinecraftInstance::getLogFileMatcher()
+{
+	auto combined = std::make_shared<MultiMatcher>();
+	combined->add(std::make_shared<RegexpMatcher>(".*\\.log(\\.[0-9]*)?(\\.gz)?$"));
+	combined->add(std::make_shared<RegexpMatcher>("crash-.*\\.txt"));
+	combined->add(std::make_shared<RegexpMatcher>("IDMap dump.*\\.txt$"));
+	combined->add(std::make_shared<RegexpMatcher>("ModLoader\\.txt(\\..*)?$"));
+	return combined;
+}
+
+QString MinecraftInstance::getLogFileRoot()
+{
+	return minecraftRoot();
+}
+
+QString MinecraftInstance::prettifyTimeDuration(int64_t duration)
+{
+	int seconds = (int) (duration % 60);
+	duration /= 60;
+	int minutes = (int) (duration % 60);
+	duration /= 60;
+	int hours = (int) (duration % 24);
+	int days = (int) (duration / 24);
+	if((hours == 0)&&(days == 0))
+	{
+		return tr("%1m %2s").arg(minutes).arg(seconds);
+	}
+	if (days == 0)
+	{
+		return tr("%1h %2m").arg(hours).arg(minutes);
+	}
+	return tr("%1d %2h %3m").arg(days).arg(hours).arg(minutes);
+}
+
+QString MinecraftInstance::getStatusbarDescription()
+{
+	QStringList traits;
+	if (flags() & VersionBrokenFlag)
+	{
+		traits.append(tr("broken"));
+	}
+
+	QString description;
+	description.append(tr("Minecraft %1 (%2)").arg(intendedVersionId()).arg(typeName()));
+	if(totalTimePlayed() > 0)
+	{
+		description.append(tr(", played for %1").arg(prettifyTimeDuration(totalTimePlayed())));
+	}
+	/*
+	if(traits.size())
+	{
+		description.append(QString(" (%1)").arg(traits.join(", ")));
+	}
+	*/
+	return description;
+}
+
+#include "MinecraftInstance.moc"
diff --git a/libraries/logic/minecraft/MinecraftInstance.h b/libraries/logic/minecraft/MinecraftInstance.h
new file mode 100644
index 00000000..cd3a8d90
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftInstance.h
@@ -0,0 +1,69 @@
+#pragma once
+#include "BaseInstance.h"
+#include "minecraft/Mod.h"
+#include <QProcess>
+
+#include "multimc_logic_export.h"
+
+class ModList;
+class WorldList;
+
+class MULTIMC_LOGIC_EXPORT MinecraftInstance: public BaseInstance
+{
+public:
+	MinecraftInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+	virtual ~MinecraftInstance() {};
+
+	/// Path to the instance's minecraft directory.
+	QString minecraftRoot() const;
+
+	//////  Mod Lists  //////
+	virtual std::shared_ptr<ModList> resourcePackList() const
+	{
+		return nullptr;
+	}
+	virtual std::shared_ptr<ModList> texturePackList() const
+	{
+		return nullptr;
+	}
+	virtual std::shared_ptr<WorldList> worldList() const
+	{
+		return nullptr;
+	}
+	/// get all jar mods applicable to this instance's jar
+	virtual QList<Mod> getJarMods() const
+	{
+		return QList<Mod>();
+	}
+
+	/// get the launch script to be used with this 
+	virtual QString createLaunchScript(AuthSessionPtr session) = 0;
+
+	//FIXME: nuke?
+	virtual std::shared_ptr<BaseVersionList> versionList() const override;
+
+	/// get arguments passed to java
+	QStringList javaArguments() const;
+
+	/// get variables for launch command variable substitution/environment
+	virtual QMap<QString, QString> getVariables() const override;
+
+	/// create an environment for launching processes
+	virtual QProcessEnvironment createEnvironment() override;
+
+	/// guess log level from a line of minecraft log
+	virtual MessageLevel::Enum guessLevel(const QString &line, MessageLevel::Enum level) override;
+
+	virtual IPathMatcher::Ptr getLogFileMatcher() override;
+
+	virtual QString getLogFileRoot() override;
+
+	virtual QString getStatusbarDescription() override;
+
+protected:
+	QMap<QString, QString> createCensorFilterFromSession(AuthSessionPtr session);
+private:
+	QString prettifyTimeDuration(int64_t duration);
+};
+
+typedef std::shared_ptr<MinecraftInstance> MinecraftInstancePtr;
diff --git a/libraries/logic/minecraft/MinecraftProfile.cpp b/libraries/logic/minecraft/MinecraftProfile.cpp
new file mode 100644
index 00000000..70d0cee4
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftProfile.cpp
@@ -0,0 +1,610 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QFile>
+#include <QCryptographicHash>
+#include <Version.h>
+#include <QDir>
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QDebug>
+
+#include "minecraft/MinecraftProfile.h"
+#include "ProfileUtils.h"
+#include "ProfileStrategy.h"
+#include "Exception.h"
+
+MinecraftProfile::MinecraftProfile(ProfileStrategy *strategy)
+	: QAbstractListModel()
+{
+	setStrategy(strategy);
+	clear();
+}
+
+void MinecraftProfile::setStrategy(ProfileStrategy* strategy)
+{
+	Q_ASSERT(strategy != nullptr);
+
+	if(m_strategy != nullptr)
+	{
+		delete m_strategy;
+		m_strategy = nullptr;
+	}
+	m_strategy = strategy;
+	m_strategy->profile = this;
+}
+
+ProfileStrategy* MinecraftProfile::strategy()
+{
+	return m_strategy;
+}
+
+void MinecraftProfile::reload()
+{
+	beginResetModel();
+	m_strategy->load();
+	reapplyPatches();
+	endResetModel();
+}
+
+void MinecraftProfile::clear()
+{
+	m_minecraftVersion.clear();
+	m_minecraftVersionType.clear();
+	m_minecraftAssets.reset();
+	m_minecraftArguments.clear();
+	m_tweakers.clear();
+	m_mainClass.clear();
+	m_appletClass.clear();
+	m_libraries.clear();
+	m_traits.clear();
+	m_jarMods.clear();
+	mojangDownloads.clear();
+	m_problemSeverity = ProblemSeverity::PROBLEM_NONE;
+}
+
+void MinecraftProfile::clearPatches()
+{
+	beginResetModel();
+	m_patches.clear();
+	endResetModel();
+}
+
+void MinecraftProfile::appendPatch(ProfilePatchPtr patch)
+{
+	int index = m_patches.size();
+	beginInsertRows(QModelIndex(), index, index);
+	m_patches.append(patch);
+	endInsertRows();
+}
+
+bool MinecraftProfile::remove(const int index)
+{
+	auto patch = versionPatch(index);
+	if (!patch->isRemovable())
+	{
+		qDebug() << "Patch" << patch->getID() << "is non-removable";
+		return false;
+	}
+
+	if(!m_strategy->removePatch(patch))
+	{
+		qCritical() << "Patch" << patch->getID() << "could not be removed";
+		return false;
+	}
+
+	beginRemoveRows(QModelIndex(), index, index);
+	m_patches.removeAt(index);
+	endRemoveRows();
+	reapplyPatches();
+	saveCurrentOrder();
+	return true;
+}
+
+bool MinecraftProfile::remove(const QString id)
+{
+	int i = 0;
+	for (auto patch : m_patches)
+	{
+		if (patch->getID() == id)
+		{
+			return remove(i);
+		}
+		i++;
+	}
+	return false;
+}
+
+bool MinecraftProfile::customize(int index)
+{
+	auto patch = versionPatch(index);
+	if (!patch->isCustomizable())
+	{
+		qDebug() << "Patch" << patch->getID() << "is not customizable";
+		return false;
+	}
+	if(!m_strategy->customizePatch(patch))
+	{
+		qCritical() << "Patch" << patch->getID() << "could not be customized";
+		return false;
+	}
+	reapplyPatches();
+	saveCurrentOrder();
+	// FIXME: maybe later in unstable
+	// emit dataChanged(createIndex(index, 0), createIndex(index, columnCount(QModelIndex()) - 1));
+	return true;
+}
+
+bool MinecraftProfile::revertToBase(int index)
+{
+	auto patch = versionPatch(index);
+	if (!patch->isRevertible())
+	{
+		qDebug() << "Patch" << patch->getID() << "is not revertible";
+		return false;
+	}
+	if(!m_strategy->revertPatch(patch))
+	{
+		qCritical() << "Patch" << patch->getID() << "could not be reverted";
+		return false;
+	}
+	reapplyPatches();
+	saveCurrentOrder();
+	// FIXME: maybe later in unstable
+	// emit dataChanged(createIndex(index, 0), createIndex(index, columnCount(QModelIndex()) - 1));
+	return true;
+}
+
+ProfilePatchPtr MinecraftProfile::versionPatch(const QString &id)
+{
+	for (auto file : m_patches)
+	{
+		if (file->getID() == id)
+		{
+			return file;
+		}
+	}
+	return nullptr;
+}
+
+ProfilePatchPtr MinecraftProfile::versionPatch(int index)
+{
+	if(index < 0 || index >= m_patches.size())
+		return nullptr;
+	return m_patches[index];
+}
+
+bool MinecraftProfile::isVanilla()
+{
+	for(auto patchptr: m_patches)
+	{
+		if(patchptr->isCustom())
+			return false;
+	}
+	return true;
+}
+
+bool MinecraftProfile::revertToVanilla()
+{
+	// remove patches, if present
+	auto VersionPatchesCopy = m_patches;
+	for(auto & it: VersionPatchesCopy)
+	{
+		if (!it->isCustom())
+		{
+			continue;
+		}
+		if(it->isRevertible() || it->isRemovable())
+		{
+			if(!remove(it->getID()))
+			{
+				qWarning() << "Couldn't remove" << it->getID() << "from profile!";
+				reapplyPatches();
+				saveCurrentOrder();
+				return false;
+			}
+		}
+	}
+	reapplyPatches();
+	saveCurrentOrder();
+	return true;
+}
+
+QVariant MinecraftProfile::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	int row = index.row();
+	int column = index.column();
+
+	if (row < 0 || row >= m_patches.size())
+		return QVariant();
+
+	auto patch = m_patches.at(row);
+
+	if (role == Qt::DisplayRole)
+	{
+		switch (column)
+		{
+		case 0:
+			return m_patches.at(row)->getName();
+		case 1:
+		{
+			if(patch->isCustom())
+			{
+				return QString("%1 (Custom)").arg(patch->getVersion());
+			}
+			else
+			{
+				return patch->getVersion();
+			}
+		}
+		default:
+			return QVariant();
+		}
+	}
+	if(role == Qt::DecorationRole)
+	{
+		switch(column)
+		{
+		case 0:
+		{
+			auto severity = patch->getProblemSeverity();
+			switch (severity)
+			{
+				case PROBLEM_WARNING:
+					return "warning";
+				case PROBLEM_ERROR:
+					return "error";
+				default:
+					return QVariant();
+			}
+		}
+		default:
+		{
+			return QVariant();
+		}
+		}
+	}
+	return QVariant();
+}
+QVariant MinecraftProfile::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	if (orientation == Qt::Horizontal)
+	{
+		if (role == Qt::DisplayRole)
+		{
+			switch (section)
+			{
+			case 0:
+				return tr("Name");
+			case 1:
+				return tr("Version");
+			default:
+				return QVariant();
+			}
+		}
+	}
+	return QVariant();
+}
+Qt::ItemFlags MinecraftProfile::flags(const QModelIndex &index) const
+{
+	if (!index.isValid())
+		return Qt::NoItemFlags;
+	return Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+}
+
+int MinecraftProfile::rowCount(const QModelIndex &parent) const
+{
+	return m_patches.size();
+}
+
+int MinecraftProfile::columnCount(const QModelIndex &parent) const
+{
+	return 2;
+}
+
+void MinecraftProfile::saveCurrentOrder() const
+{
+	ProfileUtils::PatchOrder order;
+	for(auto item: m_patches)
+	{
+		if(!item->isMoveable())
+			continue;
+		order.append(item->getID());
+	}
+	m_strategy->saveOrder(order);
+}
+
+void MinecraftProfile::move(const int index, const MoveDirection direction)
+{
+	int theirIndex;
+	if (direction == MoveUp)
+	{
+		theirIndex = index - 1;
+	}
+	else
+	{
+		theirIndex = index + 1;
+	}
+
+	if (index < 0 || index >= m_patches.size())
+		return;
+	if (theirIndex >= rowCount())
+		theirIndex = rowCount() - 1;
+	if (theirIndex == -1)
+		theirIndex = rowCount() - 1;
+	if (index == theirIndex)
+		return;
+	int togap = theirIndex > index ? theirIndex + 1 : theirIndex;
+
+	auto from = versionPatch(index);
+	auto to = versionPatch(theirIndex);
+
+	if (!from || !to || !to->isMoveable() || !from->isMoveable())
+	{
+		return;
+	}
+	beginMoveRows(QModelIndex(), index, index, QModelIndex(), togap);
+	m_patches.swap(index, theirIndex);
+	endMoveRows();
+	reapplyPatches();
+	saveCurrentOrder();
+}
+void MinecraftProfile::resetOrder()
+{
+	m_strategy->resetOrder();
+	reload();
+}
+
+bool MinecraftProfile::reapplyPatches()
+{
+	try
+	{
+		clear();
+		for(auto file: m_patches)
+		{
+			file->applyTo(this);
+		}
+	}
+	catch (Exception & error)
+	{
+		clear();
+		qWarning() << "Couldn't apply profile patches because: " << error.cause();
+		return false;
+	}
+	return true;
+}
+
+static void applyString(const QString & from, QString & to)
+{
+	if(from.isEmpty())
+		return;
+	to = from;
+}
+
+void MinecraftProfile::applyMinecraftVersion(const QString& id)
+{
+	applyString(id, this->m_minecraftVersion);
+}
+
+void MinecraftProfile::applyAppletClass(const QString& appletClass)
+{
+	applyString(appletClass, this->m_appletClass);
+}
+
+void MinecraftProfile::applyMainClass(const QString& mainClass)
+{
+	applyString(mainClass, this->m_mainClass);
+}
+
+void MinecraftProfile::applyMinecraftArguments(const QString& minecraftArguments)
+{
+	applyString(minecraftArguments, this->m_minecraftArguments);
+}
+
+void MinecraftProfile::applyMinecraftVersionType(const QString& type)
+{
+	applyString(type, this->m_minecraftVersionType);
+}
+
+void MinecraftProfile::applyMinecraftAssets(MojangAssetIndexInfo::Ptr assets)
+{
+	if(assets)
+	{
+		m_minecraftAssets = assets;
+	}
+}
+
+void MinecraftProfile::applyMojangDownload(const QString &key, MojangDownloadInfo::Ptr download)
+{
+	if(download)
+	{
+		mojangDownloads[key] = download;
+	}
+	else
+	{
+		mojangDownloads.remove(key);
+	}
+}
+
+void MinecraftProfile::applyTraits(const QSet<QString>& traits)
+{
+	this->m_traits.unite(traits);
+}
+
+void MinecraftProfile::applyTweakers(const QStringList& tweakers)
+{
+	// FIXME: check for dupes?
+	// FIXME: does order matter?
+	for (auto tweaker : tweakers)
+	{
+		this->m_tweakers += tweaker;
+	}
+}
+
+void MinecraftProfile::applyJarMods(const QList<JarmodPtr>& jarMods)
+{
+	this->m_jarMods.append(jarMods);
+}
+
+static int findLibraryByName(QList<LibraryPtr> haystack, const GradleSpecifier &needle)
+{
+	int retval = -1;
+	for (int i = 0; i < haystack.size(); ++i)
+	{
+		if (haystack.at(i)->rawName().matchName(needle))
+		{
+			// only one is allowed.
+			if (retval != -1)
+				return -1;
+			retval = i;
+		}
+	}
+	return retval;
+}
+
+void MinecraftProfile::applyLibrary(LibraryPtr library)
+{
+	if(!library->isActive())
+	{
+		return;
+	}
+	// find the library by name.
+	const int index = findLibraryByName(m_libraries, library->rawName());
+	// library not found? just add it.
+	if (index < 0)
+	{
+		m_libraries.append(Library::limitedCopy(library));
+		return;
+	}
+	auto existingLibrary = m_libraries.at(index);
+	// if we are higher it means we should update
+	if (Version(library->version()) > Version(existingLibrary->version()))
+	{
+		auto libraryCopy = Library::limitedCopy(library);
+		m_libraries.replace(index, libraryCopy);
+	}
+}
+
+void MinecraftProfile::applyProblemSeverity(ProblemSeverity severity)
+{
+	if (m_problemSeverity < severity)
+	{
+		m_problemSeverity = severity;
+	}
+}
+
+
+QString MinecraftProfile::getMinecraftVersion() const
+{
+	return m_minecraftVersion;
+}
+
+QString MinecraftProfile::getAppletClass() const
+{
+	return m_appletClass;
+}
+
+QString MinecraftProfile::getMainClass() const
+{
+	return m_mainClass;
+}
+
+const QSet<QString> &MinecraftProfile::getTraits() const
+{
+	return m_traits;
+}
+
+const QStringList & MinecraftProfile::getTweakers() const
+{
+	return m_tweakers;
+}
+
+bool MinecraftProfile::hasTrait(const QString& trait) const
+{
+	return m_traits.contains(trait);
+}
+
+ProblemSeverity MinecraftProfile::getProblemSeverity() const
+{
+	return m_problemSeverity;
+}
+
+QString MinecraftProfile::getMinecraftVersionType() const
+{
+	return m_minecraftVersionType;
+}
+
+std::shared_ptr<MojangAssetIndexInfo> MinecraftProfile::getMinecraftAssets() const
+{
+	if(!m_minecraftAssets)
+	{
+		return std::make_shared<MojangAssetIndexInfo>("legacy");
+	}
+	return m_minecraftAssets;
+}
+
+QString MinecraftProfile::getMinecraftArguments() const
+{
+	return m_minecraftArguments;
+}
+
+const QList<JarmodPtr> & MinecraftProfile::getJarMods() const
+{
+	return m_jarMods;
+}
+
+const QList<LibraryPtr> & MinecraftProfile::getLibraries() const
+{
+	return m_libraries;
+}
+
+QString MinecraftProfile::getMainJarUrl() const
+{
+	auto iter = mojangDownloads.find("client");
+	if(iter != mojangDownloads.end())
+	{
+		// current
+		return iter.value()->url;
+	}
+	else
+	{
+		// legacy fallback
+		return URLConstants::getLegacyJarUrl(getMinecraftVersion());
+	}
+}
+
+void MinecraftProfile::installJarMods(QStringList selectedFiles)
+{
+	m_strategy->installJarMods(selectedFiles);
+}
+
+/*
+ * TODO: get rid of this. Get rid of all order numbers.
+ */
+int MinecraftProfile::getFreeOrderNumber()
+{
+	int largest = 100;
+	// yes, I do realize this is dumb. The order thing itself is dumb. and to be removed next.
+	for(auto thing: m_patches)
+	{
+		int order = thing->getOrder();
+		if(order > largest)
+			largest = order;
+	}
+	return largest + 1;
+}
diff --git a/libraries/logic/minecraft/MinecraftProfile.h b/libraries/logic/minecraft/MinecraftProfile.h
new file mode 100644
index 00000000..ca9288ad
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftProfile.h
@@ -0,0 +1,200 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QAbstractListModel>
+
+#include <QString>
+#include <QList>
+#include <memory>
+
+#include "Library.h"
+#include "VersionFile.h"
+#include "JarMod.h"
+#include "MojangDownloadInfo.h"
+
+#include "multimc_logic_export.h"
+
+class ProfileStrategy;
+class OneSixInstance;
+
+
+class MULTIMC_LOGIC_EXPORT MinecraftProfile : public QAbstractListModel
+{
+	Q_OBJECT
+
+public:
+	explicit MinecraftProfile(ProfileStrategy *strategy);
+
+	void setStrategy(ProfileStrategy * strategy);
+	ProfileStrategy *strategy();
+
+	virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+	virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+	virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+	virtual int columnCount(const QModelIndex &parent) const override;
+	virtual Qt::ItemFlags flags(const QModelIndex &index) const override;
+
+	/// is this version unchanged by the user?
+	bool isVanilla();
+
+	/// remove any customizations on top of whatever 'vanilla' means
+	bool revertToVanilla();
+
+	/// install more jar mods
+	void installJarMods(QStringList selectedFiles);
+
+	/// DEPRECATED, remove ASAP
+	int getFreeOrderNumber();
+
+	enum MoveDirection { MoveUp, MoveDown };
+	/// move patch file # up or down the list
+	void move(const int index, const MoveDirection direction);
+
+	/// remove patch file # - including files/records
+	bool remove(const int index);
+
+	/// remove patch file by id - including files/records
+	bool remove(const QString id);
+
+	bool customize(int index);
+
+	bool revertToBase(int index);
+
+	void resetOrder();
+
+	/// reload all profile patches from storage, clear the profile and apply the patches
+	void reload();
+
+	/// clear the profile
+	void clear();
+
+	/// apply the patches. Catches all the errors and returns true/false for success/failure
+	bool reapplyPatches();
+
+public: /* application of profile variables from patches */
+	void applyMinecraftVersion(const QString& id);
+	void applyMainClass(const QString& mainClass);
+	void applyAppletClass(const QString& appletClass);
+	void applyMinecraftArguments(const QString& minecraftArguments);
+	void applyMinecraftVersionType(const QString& type);
+	void applyMinecraftAssets(MojangAssetIndexInfo::Ptr assets);
+	void applyTraits(const QSet<QString> &traits);
+	void applyTweakers(const QStringList &tweakers);
+	void applyJarMods(const QList<JarmodPtr> &jarMods);
+	void applyLibrary(LibraryPtr library);
+	void applyProblemSeverity(ProblemSeverity severity);
+	void applyMojangDownload(const QString & key, MojangDownloadInfo::Ptr download);
+
+public: /* getters for profile variables */
+	QString getMinecraftVersion() const;
+	QString getMainClass() const;
+	QString getAppletClass() const;
+	QString getMinecraftVersionType() const;
+	MojangAssetIndexInfo::Ptr getMinecraftAssets() const;
+	QString getMinecraftArguments() const;
+	const QSet<QString> & getTraits() const;
+	const QStringList & getTweakers() const;
+	const QList<JarmodPtr> & getJarMods() const;
+	const QList<LibraryPtr> & getLibraries() const;
+	QString getMainJarUrl() const;
+	bool hasTrait(const QString & trait) const;
+	ProblemSeverity getProblemSeverity() const;
+
+public:
+	/// get the profile patch by id
+	ProfilePatchPtr versionPatch(const QString &id);
+
+	/// get the profile patch by index
+	ProfilePatchPtr versionPatch(int index);
+
+	/// save the current patch order
+	void saveCurrentOrder() const;
+
+	/// Remove all the patches
+	void clearPatches();
+
+	/// Add the patch object to the internal list of patches
+	void appendPatch(ProfilePatchPtr patch);
+
+private: /* data */
+	/// the version of Minecraft - jar to use
+	QString m_minecraftVersion;
+
+	/// Release type - "release" or "snapshot"
+	QString m_minecraftVersionType;
+
+	/// Assets type - "legacy" or a version ID
+	MojangAssetIndexInfo::Ptr m_minecraftAssets;
+
+	// Mojang: list of 'downloads' - client jar, server jar, windows server exe, maybe more.
+	QMap <QString, std::shared_ptr<MojangDownloadInfo>> mojangDownloads;
+
+	/**
+	 * arguments that should be used for launching minecraft
+	 *
+	 * ex: "--username ${auth_player_name} --session ${auth_session}
+	 *      --version ${version_name} --gameDir ${game_directory} --assetsDir ${game_assets}"
+	 */
+	QString m_minecraftArguments;
+
+	/// A list of all tweaker classes
+	QStringList m_tweakers;
+
+	/// The main class to load first
+	QString m_mainClass;
+
+	/// The applet class, for some very old minecraft releases
+	QString m_appletClass;
+
+	/// the list of libraries
+	QList<LibraryPtr> m_libraries;
+
+	/// traits, collected from all the version files (version files can only add)
+	QSet<QString> m_traits;
+
+	/// A list of jar mods. version files can add those.
+	QList<JarmodPtr> m_jarMods;
+
+	ProblemSeverity m_problemSeverity = PROBLEM_NONE;
+
+	/*
+	FIXME: add support for those rules here? Looks like a pile of quick hacks to me though.
+
+	"rules": [
+		{
+		"action": "allow"
+		},
+		{
+		"action": "disallow",
+		"os": {
+			"name": "osx",
+			"version": "^10\\.5\\.\\d$"
+		}
+		}
+	],
+	"incompatibilityReason": "There is a bug in LWJGL which makes it incompatible with OSX
+	10.5.8. Please go to New Profile and use 1.5.2 for now. Sorry!"
+	}
+	*/
+	// QList<Rule> rules;
+
+	/// list of attached profile patches
+	QList<ProfilePatchPtr> m_patches;
+
+	/// strategy used for profile operations
+	ProfileStrategy *m_strategy = nullptr;
+};
diff --git a/libraries/logic/minecraft/MinecraftVersion.cpp b/libraries/logic/minecraft/MinecraftVersion.cpp
new file mode 100644
index 00000000..1e1d273c
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftVersion.cpp
@@ -0,0 +1,215 @@
+#include "MinecraftVersion.h"
+#include "MinecraftProfile.h"
+#include "VersionBuildError.h"
+#include "ProfileUtils.h"
+#include "settings/SettingsObject.h"
+#include "minecraft/VersionFilterData.h"
+
+bool MinecraftVersion::usesLegacyLauncher()
+{
+	return getReleaseDateTime() < g_VersionFilterData.legacyCutoffDate;
+}
+
+
+QString MinecraftVersion::descriptor()
+{
+	return m_version;
+}
+
+QString MinecraftVersion::name()
+{
+	return m_version;
+}
+
+QString MinecraftVersion::typeString() const
+{
+	if(m_type == "snapshot")
+	{
+		return QObject::tr("Snapshot");
+	}
+	else if (m_type == "release")
+	{
+		return QObject::tr("Regular release");
+	}
+	else if (m_type == "old_alpha")
+	{
+		return QObject::tr("Alpha");
+	}
+	else if (m_type == "old_beta")
+	{
+		return QObject::tr("Beta");
+	}
+	else
+	{
+		return QString();
+	}
+}
+
+VersionSource MinecraftVersion::getVersionSource()
+{
+	return m_versionSource;
+}
+
+bool MinecraftVersion::hasJarMods()
+{
+	return false;
+}
+
+bool MinecraftVersion::isMinecraftVersion()
+{
+	return true;
+}
+
+void MinecraftVersion::applyFileTo(MinecraftProfile *profile)
+{
+	if(m_versionSource == Local && getVersionFile())
+	{
+		getVersionFile()->applyTo(profile);
+	}
+	else
+	{
+		throw VersionIncomplete(QObject::tr("Can't apply incomplete/builtin Minecraft version %1").arg(m_version));
+	}
+}
+
+QString MinecraftVersion::getUrl() const
+{
+	// legacy fallback
+	if(m_versionFileURL.isEmpty())
+	{
+		return QString("http://") + URLConstants::AWS_DOWNLOAD_VERSIONS + m_version + "/" + m_version + ".json";
+	}
+	// current
+	return m_versionFileURL;
+}
+
+VersionFilePtr MinecraftVersion::getVersionFile()
+{
+	QFileInfo versionFile(QString("versions/%1/%1.dat").arg(m_version));
+	m_problems.clear();
+	if(!versionFile.exists())
+	{
+		if(m_loadedVersionFile)
+		{
+			m_loadedVersionFile.reset();
+		}
+		addProblem(PROBLEM_WARNING, QObject::tr("The patch file doesn't exist locally. It's possible it just needs to be downloaded."));
+	}
+	else
+	{
+		try
+		{
+			if(versionFile.lastModified() != m_loadedVersionFileTimestamp)
+			{
+				auto loadedVersionFile = ProfileUtils::parseBinaryJsonFile(versionFile);
+				loadedVersionFile->name = "Minecraft";
+				loadedVersionFile->setCustomizable(true);
+				m_loadedVersionFileTimestamp = versionFile.lastModified();
+				m_loadedVersionFile = loadedVersionFile;
+			}
+		}
+		catch(Exception e)
+		{
+			m_loadedVersionFile.reset();
+			addProblem(PROBLEM_ERROR, QObject::tr("The patch file couldn't be read:\n%1").arg(e.cause()));
+		}
+	}
+	return m_loadedVersionFile;
+}
+
+bool MinecraftVersion::isCustomizable()
+{
+	switch(m_versionSource)
+	{
+		case Local:
+		case Remote:
+			// locally cached file, or a remote file that we can acquire can be customized
+			return true;
+		default:
+			// Everything else is undefined and therefore not customizable.
+			return false;
+	}
+	return false;
+}
+
+const QList<PatchProblem> &MinecraftVersion::getProblems()
+{
+	if(getVersionFile())
+	{
+		return getVersionFile()->getProblems();
+	}
+	return ProfilePatch::getProblems();
+}
+
+ProblemSeverity MinecraftVersion::getProblemSeverity()
+{
+	if(getVersionFile())
+	{
+		return getVersionFile()->getProblemSeverity();
+	}
+	return ProfilePatch::getProblemSeverity();
+}
+
+void MinecraftVersion::applyTo(MinecraftProfile *profile)
+{
+	// do we have this one cached?
+	if (m_versionSource == Local)
+	{
+		applyFileTo(profile);
+		return;
+	}
+	throw VersionIncomplete(QObject::tr("Minecraft version %1 could not be applied: version files are missing.").arg(m_version));
+}
+
+int MinecraftVersion::getOrder()
+{
+	return order;
+}
+
+void MinecraftVersion::setOrder(int order)
+{
+	this->order = order;
+}
+
+QList<JarmodPtr> MinecraftVersion::getJarMods()
+{
+	return QList<JarmodPtr>();
+}
+
+QString MinecraftVersion::getName()
+{
+	return "Minecraft";
+}
+QString MinecraftVersion::getVersion()
+{
+	return m_version;
+}
+QString MinecraftVersion::getID()
+{
+	return "net.minecraft";
+}
+QString MinecraftVersion::getFilename()
+{
+	return QString();
+}
+QDateTime MinecraftVersion::getReleaseDateTime()
+{
+	return m_releaseTime;
+}
+
+
+bool MinecraftVersion::needsUpdate()
+{
+	return m_versionSource == Remote || hasUpdate();
+}
+
+bool MinecraftVersion::hasUpdate()
+{
+	return m_versionSource == Remote || (m_versionSource == Local && upstreamUpdate);
+}
+
+bool MinecraftVersion::isCustom()
+{
+	// if we add any other source types, this will evaluate to false for them.
+	return m_versionSource != Local && m_versionSource != Remote;
+}
diff --git a/libraries/logic/minecraft/MinecraftVersion.h b/libraries/logic/minecraft/MinecraftVersion.h
new file mode 100644
index 00000000..b21427d9
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftVersion.h
@@ -0,0 +1,119 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QStringList>
+#include <QSet>
+#include <QDateTime>
+
+#include "BaseVersion.h"
+#include "ProfilePatch.h"
+#include "VersionFile.h"
+
+#include "multimc_logic_export.h"
+
+class MinecraftProfile;
+class MinecraftVersion;
+typedef std::shared_ptr<MinecraftVersion> MinecraftVersionPtr;
+
+class MULTIMC_LOGIC_EXPORT MinecraftVersion : public BaseVersion, public ProfilePatch
+{
+friend class MinecraftVersionList;
+
+public: /* methods */
+	// FIXME: nuke this.
+	bool usesLegacyLauncher();
+
+	virtual QString descriptor() override;
+	virtual QString name() override;
+	virtual QString typeString() const override;
+	virtual bool hasJarMods() override;
+	virtual bool isMinecraftVersion() override;
+	virtual void applyTo(MinecraftProfile *profile) override;
+	virtual int getOrder() override;
+	virtual void setOrder(int order) override;
+	virtual QList<JarmodPtr> getJarMods() override;
+	virtual QString getID() override;
+	virtual QString getVersion() override;
+	virtual QString getName() override;
+	virtual QString getFilename() override;
+	QDateTime getReleaseDateTime() override;
+	VersionSource getVersionSource() override;
+
+	bool needsUpdate();
+	bool hasUpdate();
+	virtual bool isCustom() override;
+	virtual bool isMoveable() override
+	{
+		return false;
+	}
+	virtual bool isCustomizable() override;
+	virtual bool isRemovable() override
+	{
+		return false;
+	}
+	virtual bool isRevertible() override
+	{
+		return false;
+	}
+	virtual bool isEditable() override
+	{
+		return false;
+	}
+	virtual bool isVersionChangeable() override
+	{
+		return true;
+	}
+
+	virtual VersionFilePtr getVersionFile() override;
+
+	// virtual QJsonDocument toJson(bool saveOrder) override;
+
+	QString getUrl() const;
+
+	virtual const QList<PatchProblem> &getProblems() override;
+	virtual ProblemSeverity getProblemSeverity() override;
+
+private: /* methods */
+	void applyFileTo(MinecraftProfile *profile);
+
+protected: /* data */
+	VersionSource m_versionSource = Remote;
+
+	/// The URL that this version will be downloaded from.
+	QString m_versionFileURL;
+
+	/// the human readable version name
+	QString m_version;
+
+	/// The type of this release
+	QString m_type;
+
+	/// the time this version was actually released by Mojang
+	QDateTime m_releaseTime;
+
+	/// the time this version was last updated by Mojang
+	QDateTime m_updateTime;
+
+	/// order of this file... default = -2
+	int order = -2;
+
+	/// an update available from Mojang
+	MinecraftVersionPtr upstreamUpdate;
+
+	QDateTime m_loadedVersionFileTimestamp;
+	mutable VersionFilePtr m_loadedVersionFile;
+};
diff --git a/libraries/logic/minecraft/MinecraftVersionList.cpp b/libraries/logic/minecraft/MinecraftVersionList.cpp
new file mode 100644
index 00000000..a5cc3a39
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftVersionList.cpp
@@ -0,0 +1,591 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QtXml>
+#include "Json.h"
+#include <QtAlgorithms>
+#include <QtNetwork>
+
+#include "Env.h"
+#include "Exception.h"
+
+#include "MinecraftVersionList.h"
+#include "net/URLConstants.h"
+
+#include "ParseUtils.h"
+#include "ProfileUtils.h"
+#include "VersionFilterData.h"
+#include "onesix/OneSixVersionFormat.h"
+#include "MojangVersionFormat.h"
+#include <FileSystem.h>
+
+static const char * localVersionCache = "versions/versions.dat";
+
+class MCVListLoadTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit MCVListLoadTask(MinecraftVersionList *vlist);
+	virtual ~MCVListLoadTask() override{};
+
+	virtual void executeTask() override;
+
+protected
+slots:
+	void list_downloaded();
+
+protected:
+	QNetworkReply *vlistReply;
+	MinecraftVersionList *m_list;
+	MinecraftVersion *m_currentStable;
+};
+
+class MCVListVersionUpdateTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit MCVListVersionUpdateTask(MinecraftVersionList *vlist, std::shared_ptr<MinecraftVersion> updatedVersion);
+	virtual ~MCVListVersionUpdateTask() override{};
+	virtual void executeTask() override;
+
+protected
+slots:
+	void json_downloaded();
+
+protected:
+	NetJobPtr specificVersionDownloadJob;
+	std::shared_ptr<MinecraftVersion> updatedVersion;
+	MinecraftVersionList *m_list;
+};
+
+class ListLoadError : public Exception
+{
+public:
+	ListLoadError(QString cause) : Exception(cause) {};
+	virtual ~ListLoadError() noexcept
+	{
+	}
+};
+
+MinecraftVersionList::MinecraftVersionList(QObject *parent) : BaseVersionList(parent)
+{
+	loadCachedList();
+}
+
+Task *MinecraftVersionList::getLoadTask()
+{
+	return new MCVListLoadTask(this);
+}
+
+bool MinecraftVersionList::isLoaded()
+{
+	return m_loaded;
+}
+
+const BaseVersionPtr MinecraftVersionList::at(int i) const
+{
+	return m_vlist.at(i);
+}
+
+int MinecraftVersionList::count() const
+{
+	return m_vlist.count();
+}
+
+static bool cmpVersions(BaseVersionPtr first, BaseVersionPtr second)
+{
+	auto left = std::dynamic_pointer_cast<MinecraftVersion>(first);
+	auto right = std::dynamic_pointer_cast<MinecraftVersion>(second);
+	return left->getReleaseDateTime() > right->getReleaseDateTime();
+}
+
+void MinecraftVersionList::sortInternal()
+{
+	qSort(m_vlist.begin(), m_vlist.end(), cmpVersions);
+}
+
+void MinecraftVersionList::loadCachedList()
+{
+	QFile localIndex(localVersionCache);
+	if (!localIndex.exists())
+	{
+		return;
+	}
+	if (!localIndex.open(QIODevice::ReadOnly))
+	{
+		// FIXME: this is actually a very bad thing! How do we deal with this?
+		qCritical() << "The minecraft version cache can't be read.";
+		return;
+	}
+	auto data = localIndex.readAll();
+	try
+	{
+		localIndex.close();
+		QJsonDocument jsonDoc = QJsonDocument::fromBinaryData(data);
+		if (jsonDoc.isNull())
+		{
+			throw ListLoadError(tr("Error reading the version list."));
+		}
+		loadList(jsonDoc, Local);
+	}
+	catch (Exception &e)
+	{
+		// the cache has gone bad for some reason... flush it.
+		qCritical() << "The minecraft version cache is corrupted. Flushing cache.";
+		localIndex.remove();
+		return;
+	}
+	m_hasLocalIndex = true;
+}
+
+void MinecraftVersionList::loadList(QJsonDocument jsonDoc, VersionSource source)
+{
+	qDebug() << "Loading" << ((source == Remote) ? "remote" : "local") << "version list.";
+
+	if (!jsonDoc.isObject())
+	{
+		throw ListLoadError(tr("Error parsing version list JSON: jsonDoc is not an object"));
+	}
+
+	QJsonObject root = jsonDoc.object();
+
+	try
+	{
+		QJsonObject latest = Json::requireObject(root.value("latest"));
+		m_latestReleaseID = Json::requireString(latest.value("release"));
+		m_latestSnapshotID = Json::requireString(latest.value("snapshot"));
+	}
+	catch (Exception &err)
+	{
+		qCritical()
+			<< tr("Error parsing version list JSON: couldn't determine latest versions");
+	}
+
+	// Now, get the array of versions.
+	if (!root.value("versions").isArray())
+	{
+		throw ListLoadError(tr("Error parsing version list JSON: version list object is "
+							   "missing 'versions' array"));
+	}
+	QJsonArray versions = root.value("versions").toArray();
+
+	QList<BaseVersionPtr> tempList;
+	for (auto version : versions)
+	{
+		// Load the version info.
+		if (!version.isObject())
+		{
+			qCritical() << "Error while parsing version list : invalid JSON structure";
+			continue;
+		}
+
+		QJsonObject versionObj = version.toObject();
+		QString versionID = versionObj.value("id").toString("");
+		if (versionID.isEmpty())
+		{
+			qCritical() << "Error while parsing version : version ID is missing";
+			continue;
+		}
+
+		if (g_VersionFilterData.legacyBlacklist.contains(versionID))
+		{
+			qWarning() << "Blacklisted legacy version ignored: " << versionID;
+			continue;
+		}
+
+		// Now, we construct the version object and add it to the list.
+		std::shared_ptr<MinecraftVersion> mcVersion(new MinecraftVersion());
+		mcVersion->m_version = versionID;
+
+		mcVersion->m_releaseTime = timeFromS3Time(versionObj.value("releaseTime").toString(""));
+		mcVersion->m_updateTime = timeFromS3Time(versionObj.value("time").toString(""));
+
+		// depends on where we load the version from -- network request or local file?
+		mcVersion->m_versionSource = source;
+		mcVersion->m_versionFileURL = versionObj.value("url").toString("");
+		QString versionTypeStr = versionObj.value("type").toString("");
+		if (versionTypeStr.isEmpty())
+		{
+			qCritical() << "Ignoring" << versionID
+						 << "because it doesn't have the version type set.";
+			continue;
+		}
+		// OneSix or Legacy. use filter to determine type
+		if (versionTypeStr == "release")
+		{
+		}
+		else if (versionTypeStr == "snapshot") // It's a snapshot... yay
+		{
+		}
+		else if (versionTypeStr == "old_alpha")
+		{
+		}
+		else if (versionTypeStr == "old_beta")
+		{
+		}
+		else
+		{
+			qCritical() << "Ignoring" << versionID
+						 << "because it has an invalid version type.";
+			continue;
+		}
+		mcVersion->m_type = versionTypeStr;
+		qDebug() << "Loaded version" << versionID << "from"
+					<< ((source == Remote) ? "remote" : "local") << "version list.";
+		tempList.append(mcVersion);
+	}
+	updateListData(tempList);
+	if(source == Remote)
+	{
+		m_loaded = true;
+	}
+}
+
+void MinecraftVersionList::sortVersions()
+{
+	beginResetModel();
+	sortInternal();
+	endResetModel();
+}
+
+QVariant MinecraftVersionList::data(const QModelIndex& index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	auto version = std::dynamic_pointer_cast<MinecraftVersion>(m_vlist[index.row()]);
+	switch (role)
+	{
+	case VersionPointerRole:
+		return qVariantFromValue(m_vlist[index.row()]);
+
+	case VersionRole:
+		return version->name();
+
+	case VersionIdRole:
+		return version->descriptor();
+
+	case RecommendedRole:
+		return version->descriptor() == m_latestReleaseID;
+
+	case LatestRole:
+	{
+		if(version->descriptor() != m_latestSnapshotID)
+			return false;
+		MinecraftVersionPtr latestRelease = std::dynamic_pointer_cast<MinecraftVersion>(getLatestStable());
+		/*
+		if(latestRelease && latestRelease->m_releaseTime > version->m_releaseTime)
+		{
+			return false;
+		}
+		*/
+		return true;
+	}
+
+	case TypeRole:
+		return version->typeString();
+
+	default:
+		return QVariant();
+	}
+}
+
+BaseVersionList::RoleList MinecraftVersionList::providesRoles() const
+{
+	return {VersionPointerRole, VersionRole, VersionIdRole, RecommendedRole, LatestRole, TypeRole};
+}
+
+BaseVersionPtr MinecraftVersionList::getLatestStable() const
+{
+	if(m_lookup.contains(m_latestReleaseID))
+		return m_lookup[m_latestReleaseID];
+	return BaseVersionPtr();
+}
+
+BaseVersionPtr MinecraftVersionList::getRecommended() const
+{
+	return getLatestStable();
+}
+
+void MinecraftVersionList::updateListData(QList<BaseVersionPtr> versions)
+{
+	beginResetModel();
+	for (auto version : versions)
+	{
+		auto descr = version->descriptor();
+
+		if (!m_lookup.contains(descr))
+		{
+			m_lookup[version->descriptor()] = version;
+			m_vlist.append(version);
+			continue;
+		}
+		auto orig = std::dynamic_pointer_cast<MinecraftVersion>(m_lookup[descr]);
+		auto added = std::dynamic_pointer_cast<MinecraftVersion>(version);
+		// updateListData is called after Mojang list loads. those can be local or remote
+		// remote comes always after local
+		// any other options are ignored
+		if (orig->m_versionSource != Local || added->m_versionSource != Remote)
+		{
+			continue;
+		}
+		// alright, it's an update. put it inside the original, for further processing.
+		orig->upstreamUpdate = added;
+	}
+	sortInternal();
+	endResetModel();
+}
+
+MCVListLoadTask::MCVListLoadTask(MinecraftVersionList *vlist)
+{
+	m_list = vlist;
+	m_currentStable = NULL;
+	vlistReply = nullptr;
+}
+
+void MCVListLoadTask::executeTask()
+{
+	setStatus(tr("Loading instance version list..."));
+	auto worker = ENV.qnam();
+	vlistReply = worker->get(QNetworkRequest(QUrl("https://launchermeta.mojang.com/mc/game/version_manifest.json")));
+	connect(vlistReply, SIGNAL(finished()), this, SLOT(list_downloaded()));
+}
+
+void MCVListLoadTask::list_downloaded()
+{
+	if (vlistReply->error() != QNetworkReply::NoError)
+	{
+		vlistReply->deleteLater();
+		emitFailed("Failed to load Minecraft main version list" + vlistReply->errorString());
+		return;
+	}
+
+	auto data = vlistReply->readAll();
+	vlistReply->deleteLater();
+	try
+	{
+		QJsonParseError jsonError;
+		QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+		if (jsonError.error != QJsonParseError::NoError)
+		{
+			throw ListLoadError(
+				tr("Error parsing version list JSON: %1").arg(jsonError.errorString()));
+		}
+		m_list->loadList(jsonDoc, Remote);
+	}
+	catch (Exception &e)
+	{
+		emitFailed(e.cause());
+		return;
+	}
+
+	emitSucceeded();
+	return;
+}
+
+MCVListVersionUpdateTask::MCVListVersionUpdateTask(MinecraftVersionList *vlist, std::shared_ptr<MinecraftVersion> updatedVersion)
+	: Task()
+{
+	m_list = vlist;
+	this->updatedVersion = updatedVersion;
+}
+
+void MCVListVersionUpdateTask::executeTask()
+{
+	auto job = new NetJob("Version index");
+	job->addNetAction(ByteArrayDownload::make(QUrl(updatedVersion->getUrl())));
+	specificVersionDownloadJob.reset(job);
+	connect(specificVersionDownloadJob.get(), SIGNAL(succeeded()), SLOT(json_downloaded()));
+	connect(specificVersionDownloadJob.get(), SIGNAL(failed(QString)), SIGNAL(failed(QString)));
+	connect(specificVersionDownloadJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	specificVersionDownloadJob->start();
+}
+
+void MCVListVersionUpdateTask::json_downloaded()
+{
+	NetActionPtr DlJob = specificVersionDownloadJob->first();
+	auto data = std::dynamic_pointer_cast<ByteArrayDownload>(DlJob)->m_data;
+	specificVersionDownloadJob.reset();
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		emitFailed(tr("The download version file is not valid."));
+		return;
+	}
+	VersionFilePtr file;
+	try
+	{
+		file = MojangVersionFormat::versionFileFromJson(jsonDoc, "net.minecraft.json");
+	}
+	catch (Exception &e)
+	{
+		emitFailed(tr("Couldn't process version file: %1").arg(e.cause()));
+		return;
+	}
+
+	// Strip LWJGL from the version file. We use our own.
+	ProfileUtils::removeLwjglFromPatch(file);
+
+	file->fileId = "net.minecraft";
+
+	// now dump the file to disk
+	auto doc = OneSixVersionFormat::versionFileToJson(file, false);
+	auto newdata = doc.toBinaryData();
+	auto id = updatedVersion->descriptor();
+	QString targetPath = "versions/" + id + "/" + id + ".dat";
+	FS::ensureFilePathExists(targetPath);
+	QSaveFile vfile1(targetPath);
+	if (!vfile1.open(QIODevice::Truncate | QIODevice::WriteOnly))
+	{
+		emitFailed(tr("Can't open %1 for writing.").arg(targetPath));
+		return;
+	}
+	qint64 actual = 0;
+	if ((actual = vfile1.write(newdata)) != newdata.size())
+	{
+		emitFailed(tr("Failed to write into %1. Written %2 out of %3.")
+					   .arg(targetPath)
+					   .arg(actual)
+					   .arg(newdata.size()));
+		return;
+	}
+	if (!vfile1.commit())
+	{
+		emitFailed(tr("Can't commit changes to %1").arg(targetPath));
+		return;
+	}
+
+	m_list->finalizeUpdate(id);
+	emitSucceeded();
+}
+
+std::shared_ptr<Task> MinecraftVersionList::createUpdateTask(QString version)
+{
+	auto iter = m_lookup.find(version);
+	if(iter == m_lookup.end())
+		return nullptr;
+
+	auto mcversion = std::dynamic_pointer_cast<MinecraftVersion>(*iter);
+	if(!mcversion)
+	{
+		return nullptr;
+	}
+
+	return std::shared_ptr<Task>(new MCVListVersionUpdateTask(this, mcversion));
+}
+
+void MinecraftVersionList::saveCachedList()
+{
+	// FIXME: throw.
+	if (!FS::ensureFilePathExists(localVersionCache))
+		return;
+	QSaveFile tfile(localVersionCache);
+	if (!tfile.open(QIODevice::WriteOnly | QIODevice::Truncate))
+		return;
+	QJsonObject toplevel;
+	QJsonArray entriesArr;
+	for (auto version : m_vlist)
+	{
+		auto mcversion = std::dynamic_pointer_cast<MinecraftVersion>(version);
+		// do not save the remote versions.
+		if (mcversion->m_versionSource != Local)
+			continue;
+		QJsonObject entryObj;
+
+		entryObj.insert("id", mcversion->descriptor());
+		entryObj.insert("version", mcversion->descriptor());
+		entryObj.insert("time", timeToS3Time(mcversion->m_updateTime));
+		entryObj.insert("releaseTime", timeToS3Time(mcversion->m_releaseTime));
+		entryObj.insert("url", mcversion->m_versionFileURL);
+		entryObj.insert("type", mcversion->m_type);
+		entriesArr.append(entryObj);
+	}
+	toplevel.insert("versions", entriesArr);
+
+	{
+		bool someLatest = false;
+		QJsonObject latestObj;
+		if(!m_latestReleaseID.isNull())
+		{
+			latestObj.insert("release", m_latestReleaseID);
+			someLatest = true;
+		}
+		if(!m_latestSnapshotID.isNull())
+		{
+			latestObj.insert("snapshot", m_latestSnapshotID);
+			someLatest = true;
+		}
+		if(someLatest)
+		{
+			toplevel.insert("latest", latestObj);
+		}
+	}
+
+	QJsonDocument doc(toplevel);
+	QByteArray jsonData = doc.toBinaryData();
+	qint64 result = tfile.write(jsonData);
+	if (result == -1)
+		return;
+	if (result != jsonData.size())
+		return;
+	tfile.commit();
+}
+
+void MinecraftVersionList::finalizeUpdate(QString version)
+{
+	int idx = -1;
+	for (int i = 0; i < m_vlist.size(); i++)
+	{
+		if (version == m_vlist[i]->descriptor())
+		{
+			idx = i;
+			break;
+		}
+	}
+	if (idx == -1)
+	{
+		return;
+	}
+
+	auto updatedVersion = std::dynamic_pointer_cast<MinecraftVersion>(m_vlist[idx]);
+
+	// if we have an update for the version, replace it, make the update local
+	if (updatedVersion->upstreamUpdate)
+	{
+		auto updatedWith = updatedVersion->upstreamUpdate;
+		updatedWith->m_versionSource = Local;
+		m_vlist[idx] = updatedWith;
+		m_lookup[version] = updatedWith;
+	}
+	else
+	{
+		// otherwise, just set the version as local;
+		updatedVersion->m_versionSource = Local;
+	}
+
+	dataChanged(index(idx), index(idx));
+
+	saveCachedList();
+}
+
+#include "MinecraftVersionList.moc"
diff --git a/libraries/logic/minecraft/MinecraftVersionList.h b/libraries/logic/minecraft/MinecraftVersionList.h
new file mode 100644
index 00000000..0fca02a7
--- /dev/null
+++ b/libraries/logic/minecraft/MinecraftVersionList.h
@@ -0,0 +1,72 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QList>
+#include <QSet>
+
+#include "BaseVersionList.h"
+#include "tasks/Task.h"
+#include "minecraft/MinecraftVersion.h"
+#include <net/NetJob.h>
+
+#include "multimc_logic_export.h"
+
+class MCVListLoadTask;
+class MCVListVersionUpdateTask;
+
+class MULTIMC_LOGIC_EXPORT MinecraftVersionList : public BaseVersionList
+{
+	Q_OBJECT
+private:
+	void sortInternal();
+	void loadList(QJsonDocument jsonDoc, VersionSource source);
+	void loadCachedList();
+	void saveCachedList();
+	void finalizeUpdate(QString version);
+public:
+	friend class MCVListLoadTask;
+	friend class MCVListVersionUpdateTask;
+
+	explicit MinecraftVersionList(QObject *parent = 0);
+
+	std::shared_ptr<Task> createUpdateTask(QString version);
+
+	virtual Task *getLoadTask() override;
+	virtual bool isLoaded() override;
+	virtual const BaseVersionPtr at(int i) const override;
+	virtual int count() const override;
+	virtual void sortVersions() override;
+	virtual QVariant data(const QModelIndex & index, int role) const override;
+	virtual RoleList providesRoles() const override;
+
+	virtual BaseVersionPtr getLatestStable() const override;
+	virtual BaseVersionPtr getRecommended() const override;
+
+protected:
+	QList<BaseVersionPtr> m_vlist;
+	QMap<QString, BaseVersionPtr> m_lookup;
+
+	bool m_loaded = false;
+	bool m_hasLocalIndex = false;
+	QString m_latestReleaseID = "INVALID";
+	QString m_latestSnapshotID = "INVALID";
+
+protected
+slots:
+	virtual void updateListData(QList<BaseVersionPtr> versions) override;
+};
diff --git a/libraries/logic/minecraft/Mod.cpp b/libraries/logic/minecraft/Mod.cpp
new file mode 100644
index 00000000..9b9f76f9
--- /dev/null
+++ b/libraries/logic/minecraft/Mod.cpp
@@ -0,0 +1,377 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QDir>
+#include <QString>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QJsonValue>
+#include <quazip.h>
+#include <quazipfile.h>
+
+#include "Mod.h"
+#include "settings/INIFile.h"
+#include <FileSystem.h>
+#include <QDebug>
+
+Mod::Mod(const QFileInfo &file)
+{
+	repath(file);
+}
+
+void Mod::repath(const QFileInfo &file)
+{
+	m_file = file;
+	QString name_base = file.fileName();
+
+	m_type = Mod::MOD_UNKNOWN;
+
+	if (m_file.isDir())
+	{
+		m_type = MOD_FOLDER;
+		m_name = name_base;
+		m_mmc_id = name_base;
+	}
+	else if (m_file.isFile())
+	{
+		if (name_base.endsWith(".disabled"))
+		{
+			m_enabled = false;
+			name_base.chop(9);
+		}
+		else
+		{
+			m_enabled = true;
+		}
+		m_mmc_id = name_base;
+		if (name_base.endsWith(".zip") || name_base.endsWith(".jar"))
+		{
+			m_type = MOD_ZIPFILE;
+			name_base.chop(4);
+		}
+		else if (name_base.endsWith(".litemod"))
+		{
+			m_type = MOD_LITEMOD;
+			name_base.chop(8);
+		}
+		else
+		{
+			m_type = MOD_SINGLEFILE;
+		}
+		m_name = name_base;
+	}
+
+	if (m_type == MOD_ZIPFILE)
+	{
+		QuaZip zip(m_file.filePath());
+		if (!zip.open(QuaZip::mdUnzip))
+			return;
+
+		QuaZipFile file(&zip);
+
+		if (zip.setCurrentFile("mcmod.info"))
+		{
+			if (!file.open(QIODevice::ReadOnly))
+			{
+				zip.close();
+				return;
+			}
+
+			ReadMCModInfo(file.readAll());
+			file.close();
+			zip.close();
+			return;
+		}
+		else if (zip.setCurrentFile("forgeversion.properties"))
+		{
+			if (!file.open(QIODevice::ReadOnly))
+			{
+				zip.close();
+				return;
+			}
+
+			ReadForgeInfo(file.readAll());
+			file.close();
+			zip.close();
+			return;
+		}
+
+		zip.close();
+	}
+	else if (m_type == MOD_FOLDER)
+	{
+		QFileInfo mcmod_info(FS::PathCombine(m_file.filePath(), "mcmod.info"));
+		if (mcmod_info.isFile())
+		{
+			QFile mcmod(mcmod_info.filePath());
+			if (!mcmod.open(QIODevice::ReadOnly))
+				return;
+			auto data = mcmod.readAll();
+			if (data.isEmpty() || data.isNull())
+				return;
+			ReadMCModInfo(data);
+		}
+	}
+	else if (m_type == MOD_LITEMOD)
+	{
+		QuaZip zip(m_file.filePath());
+		if (!zip.open(QuaZip::mdUnzip))
+			return;
+
+		QuaZipFile file(&zip);
+
+		if (zip.setCurrentFile("litemod.json"))
+		{
+			if (!file.open(QIODevice::ReadOnly))
+			{
+				zip.close();
+				return;
+			}
+
+			ReadLiteModInfo(file.readAll());
+			file.close();
+		}
+		zip.close();
+	}
+}
+
+// NEW format
+// https://github.com/MinecraftForge/FML/wiki/FML-mod-information-file/6f62b37cea040daf350dc253eae6326dd9c822c3
+
+// OLD format:
+// https://github.com/MinecraftForge/FML/wiki/FML-mod-information-file/5bf6a2d05145ec79387acc0d45c958642fb049fc
+void Mod::ReadMCModInfo(QByteArray contents)
+{
+	auto getInfoFromArray = [&](QJsonArray arr)->void
+	{
+		if (!arr.at(0).isObject())
+			return;
+		auto firstObj = arr.at(0).toObject();
+		m_mod_id = firstObj.value("modid").toString();
+		m_name = firstObj.value("name").toString();
+		m_version = firstObj.value("version").toString();
+		m_homeurl = firstObj.value("url").toString();
+		m_updateurl = firstObj.value("updateUrl").toString();
+		m_homeurl = m_homeurl.trimmed();
+		if(!m_homeurl.isEmpty())
+		{
+			// fix up url.
+			if (!m_homeurl.startsWith("http://") && !m_homeurl.startsWith("https://") &&
+				!m_homeurl.startsWith("ftp://"))
+			{
+				m_homeurl.prepend("http://");
+			}
+		}
+		m_description = firstObj.value("description").toString();
+		QJsonArray authors = firstObj.value("authorList").toArray();
+		if (authors.size() == 0)
+			authors = firstObj.value("authors").toArray();
+
+		if (authors.size() == 0)
+			m_authors = "";
+		else if (authors.size() >= 1)
+		{
+			m_authors = authors.at(0).toString();
+			for (int i = 1; i < authors.size(); i++)
+			{
+				m_authors += ", " + authors.at(i).toString();
+			}
+		}
+		m_credits = firstObj.value("credits").toString();
+		return;
+	}
+	;
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(contents, &jsonError);
+	// this is the very old format that had just the array
+	if (jsonDoc.isArray())
+	{
+		getInfoFromArray(jsonDoc.array());
+	}
+	else if (jsonDoc.isObject())
+	{
+		auto val = jsonDoc.object().value("modinfoversion");
+		if(val.isUndefined())
+			val = jsonDoc.object().value("modListVersion");
+		int version = val.toDouble();
+		if (version != 2)
+		{
+			qCritical() << "BAD stuff happened to mod json:";
+			qCritical() << contents;
+			return;
+		}
+		auto arrVal = jsonDoc.object().value("modlist");
+		if(arrVal.isUndefined())
+			arrVal = jsonDoc.object().value("modList");
+		if (arrVal.isArray())
+		{
+			getInfoFromArray(arrVal.toArray());
+		}
+	}
+}
+
+void Mod::ReadForgeInfo(QByteArray contents)
+{
+	// Read the data
+	m_name = "Minecraft Forge";
+	m_mod_id = "Forge";
+	m_homeurl = "http://www.minecraftforge.net/forum/";
+	INIFile ini;
+	if (!ini.loadFile(contents))
+		return;
+
+	QString major = ini.get("forge.major.number", "0").toString();
+	QString minor = ini.get("forge.minor.number", "0").toString();
+	QString revision = ini.get("forge.revision.number", "0").toString();
+	QString build = ini.get("forge.build.number", "0").toString();
+
+	m_version = major + "." + minor + "." + revision + "." + build;
+}
+
+void Mod::ReadLiteModInfo(QByteArray contents)
+{
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(contents, &jsonError);
+	auto object = jsonDoc.object();
+	if (object.contains("name"))
+	{
+		m_mod_id = m_name = object.value("name").toString();
+	}
+	if (object.contains("version"))
+	{
+		m_version = object.value("version").toString("");
+	}
+	else
+	{
+		m_version = object.value("revision").toString("");
+	}
+	m_mcversion = object.value("mcversion").toString();
+	m_authors = object.value("author").toString();
+	m_description = object.value("description").toString();
+	m_homeurl = object.value("url").toString();
+}
+
+bool Mod::replace(Mod &with)
+{
+	if (!destroy())
+		return false;
+	bool success = false;
+	auto t = with.type();
+
+	if (t == MOD_ZIPFILE || t == MOD_SINGLEFILE || t == MOD_LITEMOD)
+	{
+		qDebug() << "Copy: " << with.m_file.filePath() << " to " << m_file.filePath();
+		success = QFile::copy(with.m_file.filePath(), m_file.filePath());
+	}
+	if (t == MOD_FOLDER)
+	{
+		success = FS::copy(with.m_file.filePath(), m_file.path())();
+	}
+	if (success)
+	{
+		m_name = with.m_name;
+		m_mmc_id = with.m_mmc_id;
+		m_mod_id = with.m_mod_id;
+		m_version = with.m_version;
+		m_mcversion = with.m_mcversion;
+		m_description = with.m_description;
+		m_authors = with.m_authors;
+		m_credits = with.m_credits;
+		m_homeurl = with.m_homeurl;
+		m_type = with.m_type;
+		m_file.refresh();
+	}
+	return success;
+}
+
+bool Mod::destroy()
+{
+	if (m_type == MOD_FOLDER)
+	{
+		QDir d(m_file.filePath());
+		if (d.removeRecursively())
+		{
+			m_type = MOD_UNKNOWN;
+			return true;
+		}
+		return false;
+	}
+	else if (m_type == MOD_SINGLEFILE || m_type == MOD_ZIPFILE || m_type == MOD_LITEMOD)
+	{
+		QFile f(m_file.filePath());
+		if (f.remove())
+		{
+			m_type = MOD_UNKNOWN;
+			return true;
+		}
+		return false;
+	}
+	return true;
+}
+
+QString Mod::version() const
+{
+	switch (type())
+	{
+	case MOD_ZIPFILE:
+	case MOD_LITEMOD:
+		return m_version;
+	case MOD_FOLDER:
+		return "Folder";
+	case MOD_SINGLEFILE:
+		return "File";
+	default:
+		return "VOID";
+	}
+}
+
+bool Mod::enable(bool value)
+{
+	if (m_type == Mod::MOD_UNKNOWN || m_type == Mod::MOD_FOLDER)
+		return false;
+
+	if (m_enabled == value)
+		return false;
+
+	QString path = m_file.absoluteFilePath();
+	if (value)
+	{
+		QFile foo(path);
+		if (!path.endsWith(".disabled"))
+			return false;
+		path.chop(9);
+		if (!foo.rename(path))
+			return false;
+	}
+	else
+	{
+		QFile foo(path);
+		path += ".disabled";
+		if (!foo.rename(path))
+			return false;
+	}
+	m_file = QFileInfo(path);
+	m_enabled = value;
+	return true;
+}
+bool Mod::operator==(const Mod &other) const
+{
+	return mmc_id() == other.mmc_id();
+}
+bool Mod::strongCompare(const Mod &other) const
+{
+	return mmc_id() == other.mmc_id() && version() == other.version() && type() == other.type();
+}
diff --git a/libraries/logic/minecraft/Mod.h b/libraries/logic/minecraft/Mod.h
new file mode 100644
index 00000000..19f4c740
--- /dev/null
+++ b/libraries/logic/minecraft/Mod.h
@@ -0,0 +1,134 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QFileInfo>
+
+class Mod
+{
+public:
+	enum ModType
+	{
+		MOD_UNKNOWN,	//!< Indicates an unspecified mod type.
+		MOD_ZIPFILE,	//!< The mod is a zip file containing the mod's class files.
+		MOD_SINGLEFILE, //!< The mod is a single file (not a zip file).
+		MOD_FOLDER,	 //!< The mod is in a folder on the filesystem.
+		MOD_LITEMOD, //!< The mod is a litemod
+	};
+
+	Mod(const QFileInfo &file);
+
+	QFileInfo filename() const
+	{
+		return m_file;
+	}
+	QString mmc_id() const
+	{
+		return m_mmc_id;
+	}
+	QString mod_id() const
+	{
+		return m_mod_id;
+	}
+	ModType type() const
+	{
+		return m_type;
+	}
+	QString mcversion() const
+	{
+		return m_mcversion;
+	}
+	;
+	bool valid()
+	{
+		return m_type != MOD_UNKNOWN;
+	}
+	QString name() const
+	{
+		if(m_name.trimmed().isEmpty())
+		{
+			return m_mmc_id;
+		}
+		return m_name;
+	}
+
+	QString version() const;
+
+	QString homeurl() const
+	{
+		return m_homeurl;
+	}
+
+	QString description() const
+	{
+		return m_description;
+	}
+
+	QString authors() const
+	{
+		return m_authors;
+	}
+
+	QString credits() const
+	{
+		return m_credits;
+	}
+
+	bool enabled() const
+	{
+		return m_enabled;
+	}
+
+	bool enable(bool value);
+
+	// delete all the files of this mod
+	bool destroy();
+	// replace this mod with a copy of the other
+	bool replace(Mod &with);
+	// change the mod's filesystem path (used by mod lists for *MAGIC* purposes)
+	void repath(const QFileInfo &file);
+
+	// WEAK compare operator - used for replacing mods
+	bool operator==(const Mod &other) const;
+	bool strongCompare(const Mod &other) const;
+
+private:
+	void ReadMCModInfo(QByteArray contents);
+	void ReadForgeInfo(QByteArray contents);
+	void ReadLiteModInfo(QByteArray contents);
+
+protected:
+
+	// FIXME: what do do with those? HMM...
+	/*
+	void ReadModInfoData(QString info);
+	void ReadForgeInfoData(QString infoFileData);
+	*/
+
+	QFileInfo m_file;
+	QString m_mmc_id;
+	QString m_mod_id;
+	bool m_enabled = true;
+	QString m_name;
+	QString m_version;
+	QString m_mcversion;
+	QString m_homeurl;
+	QString m_updateurl;
+	QString m_description;
+	QString m_authors;
+	QString m_credits;
+
+	ModType m_type;
+};
diff --git a/libraries/logic/minecraft/ModList.cpp b/libraries/logic/minecraft/ModList.cpp
new file mode 100644
index 00000000..d9ed4886
--- /dev/null
+++ b/libraries/logic/minecraft/ModList.cpp
@@ -0,0 +1,616 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ModList.h"
+#include <FileSystem.h>
+#include <QMimeData>
+#include <QUrl>
+#include <QUuid>
+#include <QString>
+#include <QFileSystemWatcher>
+#include <QDebug>
+
+ModList::ModList(const QString &dir, const QString &list_file)
+	: QAbstractListModel(), m_dir(dir), m_list_file(list_file)
+{
+	FS::ensureFolderPathExists(m_dir.absolutePath());
+	m_dir.setFilter(QDir::Readable | QDir::NoDotAndDotDot | QDir::Files | QDir::Dirs |
+					QDir::NoSymLinks);
+	m_dir.setSorting(QDir::Name | QDir::IgnoreCase | QDir::LocaleAware);
+	m_list_id = QUuid::createUuid().toString();
+	m_watcher = new QFileSystemWatcher(this);
+	is_watching = false;
+	connect(m_watcher, SIGNAL(directoryChanged(QString)), this,
+			SLOT(directoryChanged(QString)));
+}
+
+void ModList::startWatching()
+{
+	update();
+	is_watching = m_watcher->addPath(m_dir.absolutePath());
+	if (is_watching)
+	{
+		qDebug() << "Started watching " << m_dir.absolutePath();
+	}
+	else
+	{
+		qDebug() << "Failed to start watching " << m_dir.absolutePath();
+	}
+}
+
+void ModList::stopWatching()
+{
+	is_watching = !m_watcher->removePath(m_dir.absolutePath());
+	if (!is_watching)
+	{
+		qDebug() << "Stopped watching " << m_dir.absolutePath();
+	}
+	else
+	{
+		qDebug() << "Failed to stop watching " << m_dir.absolutePath();
+	}
+}
+
+void ModList::internalSort(QList<Mod> &what)
+{
+	auto predicate = [](const Mod &left, const Mod &right)
+	{
+		if (left.name() == right.name())
+		{
+			return left.mmc_id().localeAwareCompare(right.mmc_id()) < 0;
+		}
+		return left.name().localeAwareCompare(right.name()) < 0;
+	};
+	std::sort(what.begin(), what.end(), predicate);
+}
+
+bool ModList::update()
+{
+	if (!isValid())
+		return false;
+
+	QList<Mod> orderedMods;
+	QList<Mod> newMods;
+	m_dir.refresh();
+	auto folderContents = m_dir.entryInfoList();
+	bool orderOrStateChanged = false;
+
+	// first, process the ordered items (if any)
+	OrderList listOrder = readListFile();
+	for (auto item : listOrder)
+	{
+		QFileInfo infoEnabled(m_dir.filePath(item.id));
+		QFileInfo infoDisabled(m_dir.filePath(item.id + ".disabled"));
+		int idxEnabled = folderContents.indexOf(infoEnabled);
+		int idxDisabled = folderContents.indexOf(infoDisabled);
+		bool isEnabled;
+		// if both enabled and disabled versions are present, it's a special case...
+		if (idxEnabled >= 0 && idxDisabled >= 0)
+		{
+			// we only process the one we actually have in the order file.
+			// and exactly as we have it.
+			// THIS IS A CORNER CASE
+			isEnabled = item.enabled;
+		}
+		else
+		{
+			// only one is present.
+			// we pick the one that we found.
+			// we assume the mod was enabled/disabled by external means
+			isEnabled = idxEnabled >= 0;
+		}
+		int idx = isEnabled ? idxEnabled : idxDisabled;
+		QFileInfo &info = isEnabled ? infoEnabled : infoDisabled;
+		// if the file from the index file exists
+		if (idx != -1)
+		{
+			// remove from the actual folder contents list
+			folderContents.takeAt(idx);
+			// append the new mod
+			orderedMods.append(Mod(info));
+			if (isEnabled != item.enabled)
+				orderOrStateChanged = true;
+		}
+		else
+		{
+			orderOrStateChanged = true;
+		}
+	}
+	// if there are any untracked files...
+	if (folderContents.size())
+	{
+		// the order surely changed!
+		for (auto entry : folderContents)
+		{
+			newMods.append(Mod(entry));
+		}
+		internalSort(newMods);
+		orderedMods.append(newMods);
+		orderOrStateChanged = true;
+	}
+	// otherwise, if we were already tracking some mods
+	else if (mods.size())
+	{
+		// if the number doesn't match, order changed.
+		if (mods.size() != orderedMods.size())
+			orderOrStateChanged = true;
+		// if it does match, compare the mods themselves
+		else
+			for (int i = 0; i < mods.size(); i++)
+			{
+				if (!mods[i].strongCompare(orderedMods[i]))
+				{
+					orderOrStateChanged = true;
+					break;
+				}
+			}
+	}
+	beginResetModel();
+	mods.swap(orderedMods);
+	endResetModel();
+	if (orderOrStateChanged && !m_list_file.isEmpty())
+	{
+		qDebug() << "Mod list " << m_list_file << " changed!";
+		saveListFile();
+		emit changed();
+	}
+	return true;
+}
+
+void ModList::directoryChanged(QString path)
+{
+	update();
+}
+
+ModList::OrderList ModList::readListFile()
+{
+	OrderList itemList;
+	if (m_list_file.isNull() || m_list_file.isEmpty())
+		return itemList;
+
+	QFile textFile(m_list_file);
+	if (!textFile.open(QIODevice::ReadOnly | QIODevice::Text))
+		return OrderList();
+
+	QTextStream textStream;
+	textStream.setAutoDetectUnicode(true);
+	textStream.setDevice(&textFile);
+	while (true)
+	{
+		QString line = textStream.readLine();
+		if (line.isNull() || line.isEmpty())
+			break;
+		else
+		{
+			OrderItem it;
+			it.enabled = !line.endsWith(".disabled");
+			if (!it.enabled)
+			{
+				line.chop(9);
+			}
+			it.id = line;
+			itemList.append(it);
+		}
+	}
+	textFile.close();
+	return itemList;
+}
+
+bool ModList::saveListFile()
+{
+	if (m_list_file.isNull() || m_list_file.isEmpty())
+		return false;
+	QFile textFile(m_list_file);
+	if (!textFile.open(QIODevice::WriteOnly | QIODevice::Text | QIODevice::Truncate))
+		return false;
+	QTextStream textStream;
+	textStream.setGenerateByteOrderMark(true);
+	textStream.setCodec("UTF-8");
+	textStream.setDevice(&textFile);
+	for (auto mod : mods)
+	{
+		textStream << mod.mmc_id();
+		if (!mod.enabled())
+			textStream << ".disabled";
+		textStream << endl;
+	}
+	textFile.close();
+	return false;
+}
+
+bool ModList::isValid()
+{
+	return m_dir.exists() && m_dir.isReadable();
+}
+
+bool ModList::installMod(const QString &filename, int index)
+{
+	// NOTE: fix for GH-1178: remove trailing slash to avoid issues with using the empty result of QFileInfo::fileName
+	QFileInfo fileinfo(FS::NormalizePath(filename));
+
+	qDebug() << "installing: " << fileinfo.absoluteFilePath();
+
+	if (!fileinfo.exists() || !fileinfo.isReadable() || index < 0)
+	{
+		return false;
+	}
+	Mod m(fileinfo);
+	if (!m.valid())
+		return false;
+
+	// if it's already there, replace the original mod (in place)
+	int idx = mods.indexOf(m);
+	if (idx != -1)
+	{
+		int idx2 = mods.indexOf(m, idx + 1);
+		if (idx2 != -1)
+			return false;
+		if (mods[idx].replace(m))
+		{
+
+			auto left = this->index(index);
+			auto right = this->index(index, columnCount(QModelIndex()) - 1);
+			emit dataChanged(left, right);
+			saveListFile();
+			update();
+			return true;
+		}
+		return false;
+	}
+
+	auto type = m.type();
+	if (type == Mod::MOD_UNKNOWN)
+		return false;
+	if (type == Mod::MOD_SINGLEFILE || type == Mod::MOD_ZIPFILE || type == Mod::MOD_LITEMOD)
+	{
+		QString newpath = FS::PathCombine(m_dir.path(), fileinfo.fileName());
+		if (!QFile::copy(fileinfo.filePath(), newpath))
+			return false;
+		m.repath(newpath);
+		beginInsertRows(QModelIndex(), index, index);
+		mods.insert(index, m);
+		endInsertRows();
+		saveListFile();
+		update();
+		return true;
+	}
+	else if (type == Mod::MOD_FOLDER)
+	{
+
+		QString from = fileinfo.filePath();
+		QString to = FS::PathCombine(m_dir.path(), fileinfo.fileName());
+		if (!FS::copy(from, to)())
+			return false;
+		m.repath(to);
+		beginInsertRows(QModelIndex(), index, index);
+		mods.insert(index, m);
+		endInsertRows();
+		saveListFile();
+		update();
+		return true;
+	}
+	return false;
+}
+
+bool ModList::deleteMod(int index)
+{
+	if (index >= mods.size() || index < 0)
+		return false;
+	Mod &m = mods[index];
+	if (m.destroy())
+	{
+		beginRemoveRows(QModelIndex(), index, index);
+		mods.removeAt(index);
+		endRemoveRows();
+		saveListFile();
+		emit changed();
+		return true;
+	}
+	return false;
+}
+
+bool ModList::deleteMods(int first, int last)
+{
+	for (int i = first; i <= last; i++)
+	{
+		Mod &m = mods[i];
+		m.destroy();
+	}
+	beginRemoveRows(QModelIndex(), first, last);
+	mods.erase(mods.begin() + first, mods.begin() + last + 1);
+	endRemoveRows();
+	saveListFile();
+	emit changed();
+	return true;
+}
+
+bool ModList::moveModTo(int from, int to)
+{
+	if (from < 0 || from >= mods.size())
+		return false;
+	if (to >= rowCount())
+		to = rowCount() - 1;
+	if (to == -1)
+		to = rowCount() - 1;
+	if (from == to)
+		return false;
+	int togap = to > from ? to + 1 : to;
+	beginMoveRows(QModelIndex(), from, from, QModelIndex(), togap);
+	mods.move(from, to);
+	endMoveRows();
+	saveListFile();
+	emit changed();
+	return true;
+}
+
+bool ModList::moveModUp(int from)
+{
+	if (from > 0)
+		return moveModTo(from, from - 1);
+	return false;
+}
+
+bool ModList::moveModsUp(int first, int last)
+{
+	if (first == 0)
+		return false;
+
+	beginMoveRows(QModelIndex(), first, last, QModelIndex(), first - 1);
+	mods.move(first - 1, last);
+	endMoveRows();
+	saveListFile();
+	emit changed();
+	return true;
+}
+
+bool ModList::moveModDown(int from)
+{
+	if (from < 0)
+		return false;
+	if (from < mods.size() - 1)
+		return moveModTo(from, from + 1);
+	return false;
+}
+
+bool ModList::moveModsDown(int first, int last)
+{
+	if (last == mods.size() - 1)
+		return false;
+
+	beginMoveRows(QModelIndex(), first, last, QModelIndex(), last + 2);
+	mods.move(last + 1, first);
+	endMoveRows();
+	saveListFile();
+	emit changed();
+	return true;
+}
+
+int ModList::columnCount(const QModelIndex &parent) const
+{
+	return 3;
+}
+
+QVariant ModList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	int row = index.row();
+	int column = index.column();
+
+	if (row < 0 || row >= mods.size())
+		return QVariant();
+
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (column)
+		{
+		case NameColumn:
+			return mods[row].name();
+		case VersionColumn:
+			return mods[row].version();
+
+		default:
+			return QVariant();
+		}
+
+	case Qt::ToolTipRole:
+		return mods[row].mmc_id();
+
+	case Qt::CheckStateRole:
+		switch (column)
+		{
+		case ActiveColumn:
+			return mods[row].enabled() ? Qt::Checked : Qt::Unchecked;
+		default:
+			return QVariant();
+		}
+	default:
+		return QVariant();
+	}
+}
+
+bool ModList::setData(const QModelIndex &index, const QVariant &value, int role)
+{
+	if (index.row() < 0 || index.row() >= rowCount(index) || !index.isValid())
+	{
+		return false;
+	}
+
+	if (role == Qt::CheckStateRole)
+	{
+		auto &mod = mods[index.row()];
+		if (mod.enable(!mod.enabled()))
+		{
+			emit dataChanged(index, index);
+			return true;
+		}
+	}
+	return false;
+}
+
+QVariant ModList::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (section)
+		{
+		case ActiveColumn:
+			return QString();
+		case NameColumn:
+			return tr("Name");
+		case VersionColumn:
+			return tr("Version");
+		default:
+			return QVariant();
+		}
+
+	case Qt::ToolTipRole:
+		switch (section)
+		{
+		case ActiveColumn:
+			return tr("Is the mod enabled?");
+		case NameColumn:
+			return tr("The name of the mod.");
+		case VersionColumn:
+			return tr("The version of the mod.");
+		default:
+			return QVariant();
+		}
+	default:
+		return QVariant();
+	}
+	return QVariant();
+}
+
+Qt::ItemFlags ModList::flags(const QModelIndex &index) const
+{
+	Qt::ItemFlags defaultFlags = QAbstractListModel::flags(index);
+	if (index.isValid())
+		return Qt::ItemIsUserCheckable | Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled |
+			   defaultFlags;
+	else
+		return Qt::ItemIsDropEnabled | defaultFlags;
+}
+
+QStringList ModList::mimeTypes() const
+{
+	QStringList types;
+	types << "text/uri-list";
+	types << "text/plain";
+	return types;
+}
+
+Qt::DropActions ModList::supportedDropActions() const
+{
+	// copy from outside, move from within and other mod lists
+	return Qt::CopyAction | Qt::MoveAction;
+}
+
+Qt::DropActions ModList::supportedDragActions() const
+{
+	// move to other mod lists or VOID
+	return Qt::MoveAction;
+}
+
+QMimeData *ModList::mimeData(const QModelIndexList &indexes) const
+{
+	QMimeData *data = new QMimeData();
+
+	if (indexes.size() == 0)
+		return data;
+
+	auto idx = indexes[0];
+	int row = idx.row();
+	if (row < 0 || row >= mods.size())
+		return data;
+
+	QStringList params;
+	params << m_list_id << QString::number(row);
+	data->setText(params.join('|'));
+	return data;
+}
+
+bool ModList::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column,
+						   const QModelIndex &parent)
+{
+	if (action == Qt::IgnoreAction)
+		return true;
+	// check if the action is supported
+	if (!data || !(action & supportedDropActions()))
+		return false;
+	if (parent.isValid())
+	{
+		row = parent.row();
+		column = parent.column();
+	}
+
+	if (row > rowCount())
+		row = rowCount();
+	if (row == -1)
+		row = rowCount();
+	if (column == -1)
+		column = 0;
+	qDebug() << "Drop row: " << row << " column: " << column;
+
+	// files dropped from outside?
+	if (data->hasUrls())
+	{
+		bool was_watching = is_watching;
+		if (was_watching)
+			stopWatching();
+		auto urls = data->urls();
+		for (auto url : urls)
+		{
+			// only local files may be dropped...
+			if (!url.isLocalFile())
+				continue;
+			QString filename = url.toLocalFile();
+			installMod(filename, row);
+			// if there is no ordering, re-sort the list
+			if (m_list_file.isEmpty())
+			{
+				beginResetModel();
+				internalSort(mods);
+				endResetModel();
+			}
+		}
+		if (was_watching)
+			startWatching();
+		return true;
+	}
+	else if (data->hasText())
+	{
+		QString sourcestr = data->text();
+		auto list = sourcestr.split('|');
+		if (list.size() != 2)
+			return false;
+		QString remoteId = list[0];
+		int remoteIndex = list[1].toInt();
+		qDebug() << "move: " << sourcestr;
+		// no moving of things between two lists
+		if (remoteId != m_list_id)
+			return false;
+		// no point moving to the same place...
+		if (row == remoteIndex)
+			return false;
+		// otherwise, move the mod :D
+		moveModTo(remoteIndex, row);
+		return true;
+	}
+	return false;
+}
diff --git a/libraries/logic/minecraft/ModList.h b/libraries/logic/minecraft/ModList.h
new file mode 100644
index 00000000..05ada8ee
--- /dev/null
+++ b/libraries/logic/minecraft/ModList.h
@@ -0,0 +1,160 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QList>
+#include <QString>
+#include <QDir>
+#include <QAbstractListModel>
+
+#include "minecraft/Mod.h"
+
+#include "multimc_logic_export.h"
+
+class LegacyInstance;
+class BaseInstance;
+class QFileSystemWatcher;
+
+/**
+ * A legacy mod list.
+ * Backed by a folder.
+ */
+class MULTIMC_LOGIC_EXPORT ModList : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	enum Columns
+	{
+		ActiveColumn = 0,
+		NameColumn,
+		VersionColumn
+	};
+	ModList(const QString &dir, const QString &list_file = QString());
+
+	virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
+	virtual bool setData(const QModelIndex &index, const QVariant &value,
+						 int role = Qt::EditRole);
+
+	virtual int rowCount(const QModelIndex &parent = QModelIndex()) const
+	{
+		return size();
+	}
+	;
+	virtual QVariant headerData(int section, Qt::Orientation orientation,
+								int role = Qt::DisplayRole) const;
+	virtual int columnCount(const QModelIndex &parent) const;
+
+	size_t size() const
+	{
+		return mods.size();
+	}
+	;
+	bool empty() const
+	{
+		return size() == 0;
+	}
+	Mod &operator[](size_t index)
+	{
+		return mods[index];
+	}
+
+	/// Reloads the mod list and returns true if the list changed.
+	virtual bool update();
+
+	/**
+	 * Adds the given mod to the list at the given index - if the list supports custom ordering
+	 */
+	virtual bool installMod(const QString & filename, int index = 0);
+
+	/// Deletes the mod at the given index.
+	virtual bool deleteMod(int index);
+
+	/// Deletes all the selected mods
+	virtual bool deleteMods(int first, int last);
+
+	/**
+	 * move the mod at index to the position N
+	 * 0 is the beginning of the list, length() is the end of the list.
+	 */
+	virtual bool moveModTo(int from, int to);
+
+	/**
+	 * move the mod at index one position upwards
+	 */
+	virtual bool moveModUp(int from);
+	virtual bool moveModsUp(int first, int last);
+
+	/**
+	 * move the mod at index one position downwards
+	 */
+	virtual bool moveModDown(int from);
+	virtual bool moveModsDown(int first, int last);
+
+	/// flags, mostly to support drag&drop
+	virtual Qt::ItemFlags flags(const QModelIndex &index) const;
+	/// get data for drag action
+	virtual QMimeData *mimeData(const QModelIndexList &indexes) const;
+	/// get the supported mime types
+	virtual QStringList mimeTypes() const;
+	/// process data from drop action
+	virtual bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column,
+							  const QModelIndex &parent);
+	/// what drag actions do we support?
+	virtual Qt::DropActions supportedDragActions() const;
+
+	/// what drop actions do we support?
+	virtual Qt::DropActions supportedDropActions() const;
+
+	void startWatching();
+	void stopWatching();
+
+	virtual bool isValid();
+
+	QDir dir()
+	{
+		return m_dir;
+	}
+
+	const QList<Mod> & allMods()
+	{
+		return mods;
+	}
+
+private:
+	void internalSort(QList<Mod> & what);
+	struct OrderItem
+	{
+		QString id;
+		bool enabled = false;
+	};
+	typedef QList<OrderItem> OrderList;
+	OrderList readListFile();
+	bool saveListFile();
+private
+slots:
+	void directoryChanged(QString path);
+
+signals:
+	void changed();
+
+protected:
+	QFileSystemWatcher *m_watcher;
+	bool is_watching;
+	QDir m_dir;
+	QString m_list_file;
+	QString m_list_id;
+	QList<Mod> mods;
+};
diff --git a/libraries/logic/minecraft/MojangDownloadInfo.h b/libraries/logic/minecraft/MojangDownloadInfo.h
new file mode 100644
index 00000000..1f3306e0
--- /dev/null
+++ b/libraries/logic/minecraft/MojangDownloadInfo.h
@@ -0,0 +1,71 @@
+#pragma once
+#include <QString>
+#include <QMap>
+#include <memory>
+
+struct MojangDownloadInfo
+{
+	// types
+	typedef std::shared_ptr<MojangDownloadInfo> Ptr;
+
+	// data
+	/// Local filesystem path. WARNING: not used, only here so we can pass through mojang files unmolested!
+	QString path;
+	/// absolute URL of this file
+	QString url;
+	/// sha-1 checksum of the file
+	QString sha1;
+	/// size of the file in bytes
+	int size;
+};
+
+
+
+struct MojangLibraryDownloadInfo
+{
+	MojangLibraryDownloadInfo(MojangDownloadInfo::Ptr artifact): artifact(artifact) {};
+	MojangLibraryDownloadInfo() {};
+
+	// types
+	typedef std::shared_ptr<MojangLibraryDownloadInfo> Ptr;
+
+	// methods
+	MojangDownloadInfo *getDownloadInfo(QString classifier)
+	{
+		if (classifier.isNull())
+		{
+			return artifact.get();
+		}
+		
+		return classifiers[classifier].get();
+	}
+
+	// data
+	MojangDownloadInfo::Ptr artifact;
+	QMap<QString, MojangDownloadInfo::Ptr> classifiers;
+};
+
+
+
+struct MojangAssetIndexInfo : public MojangDownloadInfo
+{
+	// types
+	typedef std::shared_ptr<MojangAssetIndexInfo> Ptr;
+
+	// methods
+	MojangAssetIndexInfo()
+	{
+	}
+
+	MojangAssetIndexInfo(QString id)
+	{
+		this->id = id;
+		url = "https://s3.amazonaws.com/Minecraft.Download/indexes/" + id + ".json";
+		known = false;
+	}
+
+	// data
+	int totalSize;
+	QString id;
+	bool known = true;
+};
diff --git a/libraries/logic/minecraft/MojangVersionFormat.cpp b/libraries/logic/minecraft/MojangVersionFormat.cpp
new file mode 100644
index 00000000..34129c9e
--- /dev/null
+++ b/libraries/logic/minecraft/MojangVersionFormat.cpp
@@ -0,0 +1,381 @@
+#include "MojangVersionFormat.h"
+#include "onesix/OneSixVersionFormat.h"
+#include "MinecraftVersion.h"
+#include "VersionBuildError.h"
+#include "MojangDownloadInfo.h"
+
+#include "Json.h"
+using namespace Json;
+#include "ParseUtils.h"
+
+static const int CURRENT_MINIMUM_LAUNCHER_VERSION = 18;
+
+static MojangAssetIndexInfo::Ptr assetIndexFromJson (const QJsonObject &obj);
+static MojangDownloadInfo::Ptr downloadInfoFromJson (const QJsonObject &obj);
+static MojangLibraryDownloadInfo::Ptr libDownloadInfoFromJson (const QJsonObject &libObj);
+static QJsonObject assetIndexToJson (MojangAssetIndexInfo::Ptr assetidxinfo);
+static QJsonObject libDownloadInfoToJson (MojangLibraryDownloadInfo::Ptr libinfo);
+static QJsonObject downloadInfoToJson (MojangDownloadInfo::Ptr info);
+
+namespace Bits
+{
+static void readString(const QJsonObject &root, const QString &key, QString &variable)
+{
+	if (root.contains(key))
+	{
+		variable = requireString(root.value(key));
+	}
+}
+
+static void readDownloadInfo(MojangDownloadInfo::Ptr out, const QJsonObject &obj)
+{
+	// optional, not used
+	readString(obj, "path", out->path);
+	// required!
+	out->sha1 = requireString(obj, "sha1");
+	out->url = requireString(obj, "url");
+	out->size = requireInteger(obj, "size");
+}
+
+static void readAssetIndex(MojangAssetIndexInfo::Ptr out, const QJsonObject &obj)
+{
+	out->totalSize = requireInteger(obj, "totalSize");
+	out->id = requireString(obj, "id");
+	// out->known = true;
+}
+}
+
+MojangDownloadInfo::Ptr downloadInfoFromJson(const QJsonObject &obj)
+{
+	auto out = std::make_shared<MojangDownloadInfo>();
+	Bits::readDownloadInfo(out, obj);
+	return out;
+}
+
+MojangAssetIndexInfo::Ptr assetIndexFromJson(const QJsonObject &obj)
+{
+	auto out = std::make_shared<MojangAssetIndexInfo>();
+	Bits::readDownloadInfo(out, obj);
+	Bits::readAssetIndex(out, obj);
+	return out;
+}
+
+QJsonObject downloadInfoToJson(MojangDownloadInfo::Ptr info)
+{
+	QJsonObject out;
+	if(!info->path.isNull())
+	{
+		out.insert("path", info->path);
+	}
+	out.insert("sha1", info->sha1);
+	out.insert("size", info->size);
+	out.insert("url", info->url);
+	return out;
+}
+
+MojangLibraryDownloadInfo::Ptr libDownloadInfoFromJson(const QJsonObject &libObj)
+{
+	auto out = std::make_shared<MojangLibraryDownloadInfo>();
+	auto dlObj = requireObject(libObj.value("downloads"));
+	if(dlObj.contains("artifact"))
+	{
+		out->artifact = downloadInfoFromJson(requireObject(dlObj, "artifact"));
+	}
+	if(dlObj.contains("classifiers"))
+	{
+		auto classifiersObj = requireObject(dlObj, "classifiers");
+		for(auto iter = classifiersObj.begin(); iter != classifiersObj.end(); iter++)
+		{
+			auto classifier = iter.key();
+			auto classifierObj = requireObject(iter.value());
+			out->classifiers[classifier] = downloadInfoFromJson(classifierObj);
+		}
+	}
+	return out;
+}
+
+QJsonObject libDownloadInfoToJson(MojangLibraryDownloadInfo::Ptr libinfo)
+{
+	QJsonObject out;
+	if(libinfo->artifact)
+	{
+		out.insert("artifact", downloadInfoToJson(libinfo->artifact));
+	}
+	if(libinfo->classifiers.size())
+	{
+		QJsonObject classifiersOut;
+		for(auto iter = libinfo->classifiers.begin(); iter != libinfo->classifiers.end(); iter++)
+		{
+			classifiersOut.insert(iter.key(), downloadInfoToJson(iter.value()));
+		}
+		out.insert("classifiers", classifiersOut);
+	}
+	return out;
+}
+
+QJsonObject assetIndexToJson(MojangAssetIndexInfo::Ptr info)
+{
+	QJsonObject out;
+	if(!info->path.isNull())
+	{
+		out.insert("path", info->path);
+	}
+	out.insert("sha1", info->sha1);
+	out.insert("size", info->size);
+	out.insert("url", info->url);
+	out.insert("totalSize", info->totalSize);
+	out.insert("id", info->id);
+	return out;
+}
+
+void MojangVersionFormat::readVersionProperties(const QJsonObject &in, VersionFile *out)
+{
+	Bits::readString(in, "id", out->minecraftVersion);
+	Bits::readString(in, "mainClass", out->mainClass);
+	Bits::readString(in, "minecraftArguments", out->minecraftArguments);
+	if(out->minecraftArguments.isEmpty())
+	{
+		QString processArguments;
+		Bits::readString(in, "processArguments", processArguments);
+		QString toCompare = processArguments.toLower();
+		if (toCompare == "legacy")
+		{
+			out->minecraftArguments = " ${auth_player_name} ${auth_session}";
+		}
+		else if (toCompare == "username_session")
+		{
+			out->minecraftArguments = "--username ${auth_player_name} --session ${auth_session}";
+		}
+		else if (toCompare == "username_session_version")
+		{
+			out->minecraftArguments = "--username ${auth_player_name} --session ${auth_session} --version ${profile_name}";
+		}
+		else if (!toCompare.isEmpty())
+		{
+			out->addProblem(PROBLEM_ERROR, QObject::tr("processArguments is set to unknown value '%1'").arg(processArguments));
+		}
+	}
+	Bits::readString(in, "type", out->type);
+
+	Bits::readString(in, "assets", out->assets);
+	if(in.contains("assetIndex"))
+	{
+		out->mojangAssetIndex = assetIndexFromJson(requireObject(in, "assetIndex"));
+	}
+	else if (!out->assets.isNull())
+	{
+		out->mojangAssetIndex = std::make_shared<MojangAssetIndexInfo>(out->assets);
+	}
+
+	out->m_releaseTime = timeFromS3Time(in.value("releaseTime").toString(""));
+	out->m_updateTime = timeFromS3Time(in.value("time").toString(""));
+
+	if (in.contains("minimumLauncherVersion"))
+	{
+		out->minimumLauncherVersion = requireInteger(in.value("minimumLauncherVersion"));
+		if (out->minimumLauncherVersion > CURRENT_MINIMUM_LAUNCHER_VERSION)
+		{
+			out->addProblem(
+				PROBLEM_WARNING,
+				QObject::tr("The 'minimumLauncherVersion' value of this version (%1) is higher than supported by MultiMC (%2). It might not work properly!")
+					.arg(out->minimumLauncherVersion)
+					.arg(CURRENT_MINIMUM_LAUNCHER_VERSION));
+		}
+	}
+	if(in.contains("downloads"))
+	{
+		auto downloadsObj = requireObject(in, "downloads");
+		for(auto iter = downloadsObj.begin(); iter != downloadsObj.end(); iter++)
+		{
+			auto classifier = iter.key();
+			auto classifierObj = requireObject(iter.value());
+			out->mojangDownloads[classifier] = downloadInfoFromJson(classifierObj);
+		}
+	}
+}
+
+VersionFilePtr MojangVersionFormat::versionFileFromJson(const QJsonDocument &doc, const QString &filename)
+{
+	VersionFilePtr out(new VersionFile());
+	if (doc.isEmpty() || doc.isNull())
+	{
+		throw JSONValidationError(filename + " is empty or null");
+	}
+	if (!doc.isObject())
+	{
+		throw JSONValidationError(filename + " is not an object");
+	}
+
+	QJsonObject root = doc.object();
+
+	readVersionProperties(root, out.get());
+
+	out->name = "Minecraft";
+	out->fileId = "net.minecraft";
+	out->version = out->minecraftVersion;
+	out->filename = filename;
+
+
+	if (root.contains("libraries"))
+	{
+		for (auto libVal : requireArray(root.value("libraries")))
+		{
+			auto libObj = requireObject(libVal);
+
+			auto lib = MojangVersionFormat::libraryFromJson(libObj, filename);
+			out->libraries.append(lib);
+		}
+	}
+	return out;
+}
+
+void MojangVersionFormat::writeVersionProperties(const VersionFile* in, QJsonObject& out)
+{
+	writeString(out, "id", in->minecraftVersion);
+	writeString(out, "mainClass", in->mainClass);
+	writeString(out, "minecraftArguments", in->minecraftArguments);
+	writeString(out, "type", in->type);
+	if(!in->m_releaseTime.isNull())
+	{
+		writeString(out, "releaseTime", timeToS3Time(in->m_releaseTime));
+	}
+	if(!in->m_updateTime.isNull())
+	{
+		writeString(out, "time", timeToS3Time(in->m_updateTime));
+	}
+	if(in->minimumLauncherVersion != -1)
+	{
+		out.insert("minimumLauncherVersion", in->minimumLauncherVersion);
+	}
+	writeString(out, "assets", in->assets);
+	if(in->mojangAssetIndex && in->mojangAssetIndex->known)
+	{
+		out.insert("assetIndex", assetIndexToJson(in->mojangAssetIndex));
+	}
+	if(in->mojangDownloads.size())
+	{
+		QJsonObject downloadsOut;
+		for(auto iter = in->mojangDownloads.begin(); iter != in->mojangDownloads.end(); iter++)
+		{
+			downloadsOut.insert(iter.key(), downloadInfoToJson(iter.value()));
+		}
+		out.insert("downloads", downloadsOut);
+	}
+}
+
+QJsonDocument MojangVersionFormat::versionFileToJson(const VersionFilePtr &patch)
+{
+	QJsonObject root;
+	writeVersionProperties(patch.get(), root);
+	if (!patch->libraries.isEmpty())
+	{
+		QJsonArray array;
+		for (auto value: patch->libraries)
+		{
+			array.append(MojangVersionFormat::libraryToJson(value.get()));
+		}
+		root.insert("libraries", array);
+	}
+
+	// write the contents to a json document.
+	{
+		QJsonDocument out;
+		out.setObject(root);
+		return out;
+	}
+}
+
+LibraryPtr MojangVersionFormat::libraryFromJson(const QJsonObject &libObj, const QString &filename)
+{
+	LibraryPtr out(new Library());
+	if (!libObj.contains("name"))
+	{
+		throw JSONValidationError(filename + "contains a library that doesn't have a 'name' field");
+	}
+	out->m_name = libObj.value("name").toString();
+
+	Bits::readString(libObj, "url", out->m_repositoryURL);
+	if (libObj.contains("extract"))
+	{
+		out->m_hasExcludes = true;
+		auto extractObj = requireObject(libObj.value("extract"));
+		for (auto excludeVal : requireArray(extractObj.value("exclude")))
+		{
+			out->m_extractExcludes.append(requireString(excludeVal));
+		}
+	}
+	if (libObj.contains("natives"))
+	{
+		QJsonObject nativesObj = requireObject(libObj.value("natives"));
+		for (auto it = nativesObj.begin(); it != nativesObj.end(); ++it)
+		{
+			if (!it.value().isString())
+			{
+				qWarning() << filename << "contains an invalid native (skipping)";
+			}
+			OpSys opSys = OpSys_fromString(it.key());
+			if (opSys != Os_Other)
+			{
+				out->m_nativeClassifiers[opSys] = it.value().toString();
+			}
+		}
+	}
+	if (libObj.contains("rules"))
+	{
+		out->applyRules = true;
+		out->m_rules = rulesFromJsonV4(libObj);
+	}
+	if (libObj.contains("downloads"))
+	{
+		out->m_mojangDownloads = libDownloadInfoFromJson(libObj);
+	}
+	return out;
+}
+
+QJsonObject MojangVersionFormat::libraryToJson(Library *library)
+{
+	QJsonObject libRoot;
+	libRoot.insert("name", (QString)library->m_name);
+	if (!library->m_repositoryURL.isEmpty())
+	{
+		libRoot.insert("url", library->m_repositoryURL);
+	}
+	if (library->isNative())
+	{
+		QJsonObject nativeList;
+		auto iter = library->m_nativeClassifiers.begin();
+		while (iter != library->m_nativeClassifiers.end())
+		{
+			nativeList.insert(OpSys_toString(iter.key()), iter.value());
+			iter++;
+		}
+		libRoot.insert("natives", nativeList);
+		if (library->m_extractExcludes.size())
+		{
+			QJsonArray excludes;
+			QJsonObject extract;
+			for (auto exclude : library->m_extractExcludes)
+			{
+				excludes.append(exclude);
+			}
+			extract.insert("exclude", excludes);
+			libRoot.insert("extract", extract);
+		}
+	}
+	if (library->m_rules.size())
+	{
+		QJsonArray allRules;
+		for (auto &rule : library->m_rules)
+		{
+			QJsonObject ruleObj = rule->toJson();
+			allRules.append(ruleObj);
+		}
+		libRoot.insert("rules", allRules);
+	}
+	if(library->m_mojangDownloads)
+	{
+		auto downloadsObj = libDownloadInfoToJson(library->m_mojangDownloads);
+		libRoot.insert("downloads", downloadsObj);
+	}
+	return libRoot;
+}
diff --git a/libraries/logic/minecraft/MojangVersionFormat.h b/libraries/logic/minecraft/MojangVersionFormat.h
new file mode 100644
index 00000000..4e141088
--- /dev/null
+++ b/libraries/logic/minecraft/MojangVersionFormat.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include <minecraft/VersionFile.h>
+#include <minecraft/Library.h>
+#include <QJsonDocument>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT MojangVersionFormat
+{
+friend class OneSixVersionFormat;
+protected:
+	// does not include libraries
+	static void readVersionProperties(const QJsonObject& in, VersionFile* out);
+	// does not include libraries
+	static void writeVersionProperties(const VersionFile* in, QJsonObject& out);
+public:
+	// version files / profile patches
+	static VersionFilePtr versionFileFromJson(const QJsonDocument &doc, const QString &filename);
+	static QJsonDocument versionFileToJson(const VersionFilePtr &patch);
+
+	// libraries
+	static LibraryPtr libraryFromJson(const QJsonObject &libObj, const QString &filename);
+	static QJsonObject libraryToJson(Library *library);
+};
diff --git a/libraries/logic/minecraft/OpSys.cpp b/libraries/logic/minecraft/OpSys.cpp
new file mode 100644
index 00000000..4c2a236d
--- /dev/null
+++ b/libraries/logic/minecraft/OpSys.cpp
@@ -0,0 +1,42 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "OpSys.h"
+
+OpSys OpSys_fromString(QString name)
+{
+	if (name == "linux")
+		return Os_Linux;
+	if (name == "windows")
+		return Os_Windows;
+	if (name == "osx")
+		return Os_OSX;
+	return Os_Other;
+}
+
+QString OpSys_toString(OpSys name)
+{
+	switch (name)
+	{
+	case Os_Linux:
+		return "linux";
+	case Os_OSX:
+		return "osx";
+	case Os_Windows:
+		return "windows";
+	default:
+		return "other";
+	}
+}
\ No newline at end of file
diff --git a/libraries/logic/minecraft/OpSys.h b/libraries/logic/minecraft/OpSys.h
new file mode 100644
index 00000000..9ebea3de
--- /dev/null
+++ b/libraries/logic/minecraft/OpSys.h
@@ -0,0 +1,37 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QString>
+enum OpSys
+{
+	Os_Windows,
+	Os_Linux,
+	Os_OSX,
+	Os_Other
+};
+
+OpSys OpSys_fromString(QString);
+QString OpSys_toString(OpSys);
+
+#ifdef Q_OS_WIN32
+#define currentSystem Os_Windows
+#else
+#ifdef Q_OS_MAC
+#define currentSystem Os_OSX
+#else
+#define currentSystem Os_Linux
+#endif
+#endif
\ No newline at end of file
diff --git a/libraries/logic/minecraft/ParseUtils.cpp b/libraries/logic/minecraft/ParseUtils.cpp
new file mode 100644
index 00000000..ca188432
--- /dev/null
+++ b/libraries/logic/minecraft/ParseUtils.cpp
@@ -0,0 +1,34 @@
+#include <QDateTime>
+#include <QString>
+#include "ParseUtils.h"
+#include <QDebug>
+#include <cstdlib>
+
+QDateTime timeFromS3Time(QString str)
+{
+	return QDateTime::fromString(str, Qt::ISODate);
+}
+
+QString timeToS3Time(QDateTime time)
+{
+	// this all because Qt can't format timestamps right.
+	int offsetRaw = time.offsetFromUtc();
+	bool negative = offsetRaw < 0;
+	int offsetAbs = std::abs(offsetRaw);
+
+	int offsetSeconds = offsetAbs % 60;
+	offsetAbs -= offsetSeconds;
+
+	int offsetMinutes = offsetAbs % 3600;
+	offsetAbs -= offsetMinutes;
+	offsetMinutes /= 60;
+	
+	int offsetHours = offsetAbs / 3600;
+
+	QString raw = time.toString("yyyy-MM-ddTHH:mm:ss");
+	raw += (negative ? QChar('-') : QChar('+'));
+	raw += QString("%1").arg(offsetHours, 2, 10, QChar('0'));
+	raw += ":";
+	raw += QString("%1").arg(offsetMinutes, 2, 10, QChar('0'));
+	return raw;
+}
diff --git a/libraries/logic/minecraft/ParseUtils.h b/libraries/logic/minecraft/ParseUtils.h
new file mode 100644
index 00000000..2b367a10
--- /dev/null
+++ b/libraries/logic/minecraft/ParseUtils.h
@@ -0,0 +1,11 @@
+#pragma once
+#include <QString>
+#include <QDateTime>
+
+#include "multimc_logic_export.h"
+
+/// take the timestamp used by S3 and turn it into QDateTime
+MULTIMC_LOGIC_EXPORT QDateTime timeFromS3Time(QString str);
+
+/// take a timestamp and convert it into an S3 timestamp
+MULTIMC_LOGIC_EXPORT QString timeToS3Time(QDateTime);
diff --git a/libraries/logic/minecraft/ProfilePatch.h b/libraries/logic/minecraft/ProfilePatch.h
new file mode 100644
index 00000000..f0c65360
--- /dev/null
+++ b/libraries/logic/minecraft/ProfilePatch.h
@@ -0,0 +1,104 @@
+#pragma once
+
+#include <memory>
+#include <QList>
+#include <QJsonDocument>
+#include <QDateTime>
+#include "JarMod.h"
+
+class MinecraftProfile;
+
+enum ProblemSeverity
+{
+	PROBLEM_NONE,
+	PROBLEM_WARNING,
+	PROBLEM_ERROR
+};
+
+/// where is a version from?
+enum VersionSource
+{
+	Local, //!< version loaded from a file in the cache.
+	Remote, //!< incomplete version on a remote server.
+};
+
+class PatchProblem
+{
+public:
+	PatchProblem(ProblemSeverity severity, const QString & description)
+	{
+		m_severity = severity;
+		m_description = description;
+	}
+	const QString & getDescription() const
+	{
+		return m_description;
+	}
+	const ProblemSeverity getSeverity() const
+	{
+		return m_severity;
+	}
+private:
+	ProblemSeverity m_severity;
+	QString m_description;
+};
+
+class ProfilePatch : public std::enable_shared_from_this<ProfilePatch>
+{
+public:
+	virtual ~ProfilePatch(){};
+	virtual void applyTo(MinecraftProfile *profile) = 0;
+
+	virtual bool isMinecraftVersion() = 0;
+	virtual bool hasJarMods() = 0;
+	virtual QList<JarmodPtr> getJarMods() = 0;
+
+	virtual bool isMoveable() = 0;
+	virtual bool isCustomizable() = 0;
+	virtual bool isRevertible() = 0;
+	virtual bool isRemovable() = 0;
+	virtual bool isCustom() = 0;
+	virtual bool isEditable() = 0;
+	virtual bool isVersionChangeable() = 0;
+
+	virtual void setOrder(int order) = 0;
+	virtual int getOrder() = 0;
+
+	virtual QString getID() = 0;
+	virtual QString getName() = 0;
+	virtual QString getVersion() = 0;
+	virtual QDateTime getReleaseDateTime() = 0;
+
+	virtual QString getFilename() = 0;
+
+	virtual VersionSource getVersionSource() = 0;
+
+	virtual std::shared_ptr<class VersionFile> getVersionFile() = 0;
+
+	virtual const QList<PatchProblem>& getProblems()
+	{
+		return m_problems;
+	}
+	virtual void addProblem(ProblemSeverity severity, const QString &description)
+	{
+		if(severity > m_problemSeverity)
+		{
+			m_problemSeverity = severity;
+		}
+		m_problems.append(PatchProblem(severity, description));
+	}
+	virtual ProblemSeverity getProblemSeverity()
+	{
+		return m_problemSeverity;
+	}
+	virtual bool hasFailed()
+	{
+		return getProblemSeverity() == PROBLEM_ERROR;
+	}
+
+protected:
+	QList<PatchProblem> m_problems;
+	ProblemSeverity m_problemSeverity = PROBLEM_NONE;
+};
+
+typedef std::shared_ptr<ProfilePatch> ProfilePatchPtr;
diff --git a/libraries/logic/minecraft/ProfileStrategy.h b/libraries/logic/minecraft/ProfileStrategy.h
new file mode 100644
index 00000000..b4dfc4b3
--- /dev/null
+++ b/libraries/logic/minecraft/ProfileStrategy.h
@@ -0,0 +1,35 @@
+#pragma once
+
+#include "ProfileUtils.h"
+
+class MinecraftProfile;
+
+class ProfileStrategy
+{
+	friend class MinecraftProfile;
+public:
+	virtual ~ProfileStrategy(){};
+
+	/// load the patch files into the profile
+	virtual void load() = 0;
+
+	/// reset the order of patches
+	virtual bool resetOrder() = 0;
+
+	/// save the order of patches, given the order
+	virtual bool saveOrder(ProfileUtils::PatchOrder order) = 0;
+
+	/// install a list of jar mods into the instance
+	virtual bool installJarMods(QStringList filepaths) = 0;
+
+	/// remove any files or records that constitute the version patch
+	virtual bool removePatch(ProfilePatchPtr jarMod) = 0;
+
+	/// make the patch custom, if possible
+	virtual bool customizePatch(ProfilePatchPtr patch) = 0;
+
+	/// revert the custom patch to 'vanilla', if possible
+	virtual bool revertPatch(ProfilePatchPtr patch) = 0;
+protected:
+	MinecraftProfile *profile;
+};
diff --git a/libraries/logic/minecraft/ProfileUtils.cpp b/libraries/logic/minecraft/ProfileUtils.cpp
new file mode 100644
index 00000000..ef9b3b28
--- /dev/null
+++ b/libraries/logic/minecraft/ProfileUtils.cpp
@@ -0,0 +1,191 @@
+#include "ProfileUtils.h"
+#include "minecraft/VersionFilterData.h"
+#include "minecraft/onesix/OneSixVersionFormat.h"
+#include "Json.h"
+#include <QDebug>
+
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QRegularExpression>
+#include <QSaveFile>
+
+namespace ProfileUtils
+{
+
+static const int currentOrderFileVersion = 1;
+
+bool writeOverrideOrders(QString path, const PatchOrder &order)
+{
+	QJsonObject obj;
+	obj.insert("version", currentOrderFileVersion);
+	QJsonArray orderArray;
+	for(auto str: order)
+	{
+		orderArray.append(str);
+	}
+	obj.insert("order", orderArray);
+	QSaveFile orderFile(path);
+	if (!orderFile.open(QFile::WriteOnly))
+	{
+		qCritical() << "Couldn't open" << orderFile.fileName()
+					 << "for writing:" << orderFile.errorString();
+		return false;
+	}
+	auto data = QJsonDocument(obj).toJson(QJsonDocument::Indented);
+	if(orderFile.write(data) != data.size())
+	{
+		qCritical() << "Couldn't write all the data into" << orderFile.fileName()
+					 << "because:" << orderFile.errorString();
+		return false;
+	}
+	if(!orderFile.commit())
+	{
+		qCritical() << "Couldn't save" << orderFile.fileName()
+					 << "because:" << orderFile.errorString();
+	}
+	return true;
+}
+
+bool readOverrideOrders(QString path, PatchOrder &order)
+{
+	QFile orderFile(path);
+	if (!orderFile.exists())
+	{
+		qWarning() << "Order file doesn't exist. Ignoring.";
+		return false;
+	}
+	if (!orderFile.open(QFile::ReadOnly))
+	{
+		qCritical() << "Couldn't open" << orderFile.fileName()
+					 << " for reading:" << orderFile.errorString();
+		qWarning() << "Ignoring overriden order";
+		return false;
+	}
+
+	// and it's valid JSON
+	QJsonParseError error;
+	QJsonDocument doc = QJsonDocument::fromJson(orderFile.readAll(), &error);
+	if (error.error != QJsonParseError::NoError)
+	{
+		qCritical() << "Couldn't parse" << orderFile.fileName() << ":" << error.errorString();
+		qWarning() << "Ignoring overriden order";
+		return false;
+	}
+
+	// and then read it and process it if all above is true.
+	try
+	{
+		auto obj = Json::requireObject(doc);
+		// check order file version.
+		auto version = Json::requireInteger(obj.value("version"));
+		if (version != currentOrderFileVersion)
+		{
+			throw JSONValidationError(QObject::tr("Invalid order file version, expected %1")
+										  .arg(currentOrderFileVersion));
+		}
+		auto orderArray = Json::requireArray(obj.value("order"));
+		for(auto item: orderArray)
+		{
+			order.append(Json::requireString(item));
+		}
+	}
+	catch (JSONValidationError &err)
+	{
+		qCritical() << "Couldn't parse" << orderFile.fileName() << ": bad file format";
+		qWarning() << "Ignoring overriden order";
+		order.clear();
+		return false;
+	}
+	return true;
+}
+
+static VersionFilePtr createErrorVersionFile(QString fileId, QString filepath, QString error)
+{
+	auto outError = std::make_shared<VersionFile>();
+	outError->fileId = outError->name = fileId;
+	outError->filename = filepath;
+	outError->addProblem(PROBLEM_ERROR, error);
+	return outError;
+}
+
+static VersionFilePtr guardedParseJson(const QJsonDocument & doc,const QString &fileId,const QString &filepath,const bool &requireOrder)
+{
+	try
+	{
+		return OneSixVersionFormat::versionFileFromJson(doc, filepath, requireOrder);
+	}
+	catch (Exception & e)
+	{
+		return createErrorVersionFile(fileId, filepath, e.cause());
+	}
+}
+
+VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder)
+{
+	QFile file(fileInfo.absoluteFilePath());
+	if (!file.open(QFile::ReadOnly))
+	{
+		auto errorStr = QObject::tr("Unable to open the version file %1: %2.").arg(fileInfo.fileName(), file.errorString());
+		return createErrorVersionFile(fileInfo.completeBaseName(), fileInfo.absoluteFilePath(), errorStr);
+	}
+	QJsonParseError error;
+	auto data = file.readAll();
+	QJsonDocument doc = QJsonDocument::fromJson(data, &error);
+	file.close();
+	if (error.error != QJsonParseError::NoError)
+	{
+		int line = 1;
+		int column = 0;
+		for(int i = 0; i < error.offset; i++)
+		{
+			if(data[i] == '\n')
+			{
+				line++;
+				column = 0;
+				continue;
+			}
+			column++;
+		}
+		auto errorStr = QObject::tr("Unable to process the version file %1: %2 at line %3 column %4.")
+				.arg(fileInfo.fileName(), error.errorString())
+				.arg(line).arg(column);
+		return createErrorVersionFile(fileInfo.completeBaseName(), fileInfo.absoluteFilePath(), errorStr);
+	}
+	return guardedParseJson(doc, fileInfo.completeBaseName(), fileInfo.absoluteFilePath(), requireOrder);
+}
+
+VersionFilePtr parseBinaryJsonFile(const QFileInfo &fileInfo)
+{
+	QFile file(fileInfo.absoluteFilePath());
+	if (!file.open(QFile::ReadOnly))
+	{
+		auto errorStr = QObject::tr("Unable to open the version file %1: %2.").arg(fileInfo.fileName(), file.errorString());
+		return createErrorVersionFile(fileInfo.completeBaseName(), fileInfo.absoluteFilePath(), errorStr);
+	}
+	QJsonDocument doc = QJsonDocument::fromBinaryData(file.readAll());
+	file.close();
+	if (doc.isNull())
+	{
+		file.remove();
+		throw JSONValidationError(QObject::tr("Unable to process the version file %1.").arg(fileInfo.fileName()));
+	}
+	return guardedParseJson(doc, fileInfo.completeBaseName(), fileInfo.absoluteFilePath(), false);
+}
+
+void removeLwjglFromPatch(VersionFilePtr patch)
+{
+	auto filter = [](QList<LibraryPtr>& libs)
+	{
+		QList<LibraryPtr> filteredLibs;
+		for (auto lib : libs)
+		{
+			if (!g_VersionFilterData.lwjglWhitelist.contains(lib->artifactPrefix()))
+			{
+				filteredLibs.append(lib);
+			}
+		}
+		libs = filteredLibs;
+	};
+	filter(patch->libraries);
+}
+}
diff --git a/libraries/logic/minecraft/ProfileUtils.h b/libraries/logic/minecraft/ProfileUtils.h
new file mode 100644
index 00000000..267fd42b
--- /dev/null
+++ b/libraries/logic/minecraft/ProfileUtils.h
@@ -0,0 +1,25 @@
+#pragma once
+#include "Library.h"
+#include "VersionFile.h"
+
+namespace ProfileUtils
+{
+typedef QStringList PatchOrder;
+
+/// Read and parse a OneSix format order file
+bool readOverrideOrders(QString path, PatchOrder &order);
+
+/// Write a OneSix format order file
+bool writeOverrideOrders(QString path, const PatchOrder &order);
+
+
+/// Parse a version file in JSON format
+VersionFilePtr parseJsonFile(const QFileInfo &fileInfo, const bool requireOrder);
+
+/// Parse a version file in binary JSON format
+VersionFilePtr parseBinaryJsonFile(const QFileInfo &fileInfo);
+
+/// Remove LWJGL from a patch file. This is applied to all Mojang-like profile files.
+void removeLwjglFromPatch(VersionFilePtr patch);
+
+}
diff --git a/libraries/logic/minecraft/Rule.cpp b/libraries/logic/minecraft/Rule.cpp
new file mode 100644
index 00000000..c8ba297b
--- /dev/null
+++ b/libraries/logic/minecraft/Rule.cpp
@@ -0,0 +1,93 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QJsonObject>
+#include <QJsonArray>
+
+#include "Rule.h"
+
+RuleAction RuleAction_fromString(QString name)
+{
+	if (name == "allow")
+		return Allow;
+	if (name == "disallow")
+		return Disallow;
+	return Defer;
+}
+
+QList<std::shared_ptr<Rule>> rulesFromJsonV4(const QJsonObject &objectWithRules)
+{
+	QList<std::shared_ptr<Rule>> rules;
+	auto rulesVal = objectWithRules.value("rules");
+	if (!rulesVal.isArray())
+		return rules;
+
+	QJsonArray ruleList = rulesVal.toArray();
+	for (auto ruleVal : ruleList)
+	{
+		std::shared_ptr<Rule> rule;
+		if (!ruleVal.isObject())
+			continue;
+		auto ruleObj = ruleVal.toObject();
+		auto actionVal = ruleObj.value("action");
+		if (!actionVal.isString())
+			continue;
+		auto action = RuleAction_fromString(actionVal.toString());
+		if (action == Defer)
+			continue;
+
+		auto osVal = ruleObj.value("os");
+		if (!osVal.isObject())
+		{
+			// add a new implicit action rule
+			rules.append(ImplicitRule::create(action));
+			continue;
+		}
+
+		auto osObj = osVal.toObject();
+		auto osNameVal = osObj.value("name");
+		if (!osNameVal.isString())
+			continue;
+		OpSys requiredOs = OpSys_fromString(osNameVal.toString());
+		QString versionRegex = osObj.value("version").toString();
+		// add a new OS rule
+		rules.append(OsRule::create(action, requiredOs, versionRegex));
+	}
+    return rules;
+}
+
+QJsonObject ImplicitRule::toJson()
+{
+	QJsonObject ruleObj;
+	ruleObj.insert("action", m_result == Allow ? QString("allow") : QString("disallow"));
+	return ruleObj;
+}
+
+QJsonObject OsRule::toJson()
+{
+	QJsonObject ruleObj;
+	ruleObj.insert("action", m_result == Allow ? QString("allow") : QString("disallow"));
+	QJsonObject osObj;
+	{
+		osObj.insert("name", OpSys_toString(m_system));
+		if(!m_version_regexp.isEmpty())
+		{
+			osObj.insert("version", m_version_regexp);
+		}
+	}
+	ruleObj.insert("os", osObj);
+	return ruleObj;
+}
+
diff --git a/libraries/logic/minecraft/Rule.h b/libraries/logic/minecraft/Rule.h
new file mode 100644
index 00000000..c8bf6eaa
--- /dev/null
+++ b/libraries/logic/minecraft/Rule.h
@@ -0,0 +1,101 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QList>
+#include <QJsonObject>
+#include <memory>
+#include "OpSys.h"
+
+class Library;
+class Rule;
+
+enum RuleAction
+{
+	Allow,
+	Disallow,
+	Defer
+};
+
+QList<std::shared_ptr<Rule>> rulesFromJsonV4(const QJsonObject &objectWithRules);
+
+class Rule
+{
+protected:
+	RuleAction m_result;
+	virtual bool applies(const Library *parent) = 0;
+
+public:
+	Rule(RuleAction result) : m_result(result)
+	{
+	}
+	virtual ~Rule() {};
+	virtual QJsonObject toJson() = 0;
+	RuleAction apply(const Library *parent)
+	{
+		if (applies(parent))
+			return m_result;
+		else
+			return Defer;
+	}
+};
+
+class OsRule : public Rule
+{
+private:
+	// the OS
+	OpSys m_system;
+	// the OS version regexp
+	QString m_version_regexp;
+
+protected:
+	virtual bool applies(const Library *)
+	{
+		return (m_system == currentSystem);
+	}
+	OsRule(RuleAction result, OpSys system, QString version_regexp)
+		: Rule(result), m_system(system), m_version_regexp(version_regexp)
+	{
+	}
+
+public:
+	virtual QJsonObject toJson();
+	static std::shared_ptr<OsRule> create(RuleAction result, OpSys system,
+										  QString version_regexp)
+	{
+		return std::shared_ptr<OsRule>(new OsRule(result, system, version_regexp));
+	}
+};
+
+class ImplicitRule : public Rule
+{
+protected:
+	virtual bool applies(const Library *)
+	{
+		return true;
+	}
+	ImplicitRule(RuleAction result) : Rule(result)
+	{
+	}
+
+public:
+	virtual QJsonObject toJson();
+	static std::shared_ptr<ImplicitRule> create(RuleAction result)
+	{
+		return std::shared_ptr<ImplicitRule>(new ImplicitRule(result));
+	}
+};
diff --git a/libraries/logic/minecraft/VersionBuildError.h b/libraries/logic/minecraft/VersionBuildError.h
new file mode 100644
index 00000000..fda453e5
--- /dev/null
+++ b/libraries/logic/minecraft/VersionBuildError.h
@@ -0,0 +1,58 @@
+#include "Exception.h"
+
+class VersionBuildError : public Exception
+{
+public:
+	explicit VersionBuildError(QString cause) : Exception(cause) {}
+	virtual ~VersionBuildError() noexcept
+	{
+	}
+};
+
+/**
+ * the base version file was meant for a newer version of the vanilla launcher than we support
+ */
+class LauncherVersionError : public VersionBuildError
+{
+public:
+	LauncherVersionError(int actual, int supported)
+		: VersionBuildError(QObject::tr(
+			  "The base version file of this instance was meant for a newer (%1) "
+			  "version of the vanilla launcher than this version of MultiMC supports (%2).")
+								.arg(actual)
+								.arg(supported)) {};
+	virtual ~LauncherVersionError() noexcept
+	{
+	}
+};
+
+/**
+ * some patch was intended for a different version of minecraft
+ */
+class MinecraftVersionMismatch : public VersionBuildError
+{
+public:
+	MinecraftVersionMismatch(QString fileId, QString mcVersion, QString parentMcVersion)
+		: VersionBuildError(QObject::tr("The patch %1 is for a different version of Minecraft "
+										"(%2) than that of the instance (%3).")
+								.arg(fileId)
+								.arg(mcVersion)
+								.arg(parentMcVersion)) {};
+	virtual ~MinecraftVersionMismatch() noexcept
+	{
+	}
+};
+
+/**
+ * files required for the version are not (yet?) present
+ */
+class VersionIncomplete : public VersionBuildError
+{
+public:
+	VersionIncomplete(QString missingPatch)
+		: VersionBuildError(QObject::tr("Version is incomplete: missing %1.")
+								.arg(missingPatch)) {};
+	virtual ~VersionIncomplete() noexcept
+	{
+	}
+};
diff --git a/libraries/logic/minecraft/VersionFile.cpp b/libraries/logic/minecraft/VersionFile.cpp
new file mode 100644
index 00000000..573c4cb4
--- /dev/null
+++ b/libraries/logic/minecraft/VersionFile.cpp
@@ -0,0 +1,60 @@
+#include <QJsonArray>
+#include <QJsonDocument>
+
+#include <QDebug>
+
+#include "minecraft/VersionFile.h"
+#include "minecraft/Library.h"
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/JarMod.h"
+#include "ParseUtils.h"
+
+#include "VersionBuildError.h"
+#include <Version.h>
+
+bool VersionFile::isMinecraftVersion()
+{
+	return fileId == "net.minecraft";
+}
+
+bool VersionFile::hasJarMods()
+{
+	return !jarMods.isEmpty();
+}
+
+void VersionFile::applyTo(MinecraftProfile *profile)
+{
+	auto theirVersion = profile->getMinecraftVersion();
+	if (!theirVersion.isNull() && !dependsOnMinecraftVersion.isNull())
+	{
+		if (QRegExp(dependsOnMinecraftVersion, Qt::CaseInsensitive, QRegExp::Wildcard).indexIn(theirVersion) == -1)
+		{
+			throw MinecraftVersionMismatch(fileId, dependsOnMinecraftVersion, theirVersion);
+		}
+	}
+	profile->applyMinecraftVersion(minecraftVersion);
+	profile->applyMainClass(mainClass);
+	profile->applyAppletClass(appletClass);
+	profile->applyMinecraftArguments(minecraftArguments);
+	if (isMinecraftVersion())
+	{
+		profile->applyMinecraftVersionType(type);
+	}
+	profile->applyMinecraftAssets(mojangAssetIndex);
+	profile->applyTweakers(addTweakers);
+
+	profile->applyJarMods(jarMods);
+	profile->applyTraits(traits);
+
+	for (auto library : libraries)
+	{
+		profile->applyLibrary(library);
+	}
+	profile->applyProblemSeverity(getProblemSeverity());
+	auto iter = mojangDownloads.begin();
+	while(iter != mojangDownloads.end())
+	{
+		profile->applyMojangDownload(iter.key(), iter.value());
+		iter++;
+	}
+}
diff --git a/libraries/logic/minecraft/VersionFile.h b/libraries/logic/minecraft/VersionFile.h
new file mode 100644
index 00000000..1b692f0f
--- /dev/null
+++ b/libraries/logic/minecraft/VersionFile.h
@@ -0,0 +1,195 @@
+#pragma once
+
+#include <QString>
+#include <QStringList>
+#include <QDateTime>
+#include <QSet>
+
+#include <memory>
+#include "minecraft/OpSys.h"
+#include "minecraft/Rule.h"
+#include "ProfilePatch.h"
+#include "Library.h"
+#include "JarMod.h"
+
+class MinecraftProfile;
+class VersionFile;
+struct MojangDownloadInfo;
+struct MojangAssetIndexInfo;
+
+typedef std::shared_ptr<VersionFile> VersionFilePtr;
+class VersionFile : public ProfilePatch
+{
+	friend class MojangVersionFormat;
+	friend class OneSixVersionFormat;
+public: /* methods */
+	virtual void applyTo(MinecraftProfile *profile) override;
+	virtual bool isMinecraftVersion() override;
+	virtual bool hasJarMods() override;
+	virtual int getOrder() override
+	{
+		return order;
+	}
+	virtual void setOrder(int order) override
+	{
+		this->order = order;
+	}
+	virtual QList<JarmodPtr> getJarMods() override
+	{
+		return jarMods;
+	}
+	virtual QString getID() override
+	{
+		return fileId;
+	}
+	virtual QString getName() override
+	{
+		return name;
+	}
+	virtual QString getVersion() override
+	{
+		return version;
+	}
+	virtual QString getFilename() override
+	{
+		return filename;
+	}
+	virtual QDateTime getReleaseDateTime() override
+	{
+		return m_releaseTime;
+	}
+	VersionSource getVersionSource() override
+	{
+		return Local;
+	}
+
+	std::shared_ptr<class VersionFile> getVersionFile() override
+	{
+		return std::dynamic_pointer_cast<VersionFile>(shared_from_this());
+	}
+
+	virtual bool isCustom() override
+	{
+		return !m_isVanilla;
+	};
+	virtual bool isCustomizable() override
+	{
+		return m_isCustomizable;
+	}
+	virtual bool isRemovable() override
+	{
+		return m_isRemovable;
+	}
+	virtual bool isRevertible() override
+	{
+		return m_isRevertible;
+	}
+    virtual bool isMoveable() override
+	{
+		return m_isMovable;
+	}
+    virtual bool isEditable() override
+	{
+		return isCustom();
+	}
+	virtual bool isVersionChangeable() override
+	{
+		return false;
+	}
+
+	void setVanilla (bool state)
+	{
+		m_isVanilla = state;
+	}
+	void setRemovable (bool state)
+	{
+		m_isRemovable = state;
+	}
+	void setRevertible (bool state)
+	{
+		m_isRevertible = state;
+	}
+	void setCustomizable (bool state)
+	{
+		m_isCustomizable = state;
+	}
+	void setMovable (bool state)
+	{
+		m_isMovable = state;
+	}
+
+
+public: /* data */
+	/// MultiMC: order hint for this version file if no explicit order is set
+	int order = 0;
+
+	// Flags for UI and version file manipulation in general
+	bool m_isVanilla = false;
+	bool m_isRemovable = false;
+	bool m_isRevertible = false;
+	bool m_isCustomizable = false;
+	bool m_isMovable = false;
+
+	/// MultiMC: filename of the file this was loaded from
+	QString filename;
+
+	/// MultiMC: human readable name of this package
+	QString name;
+
+	/// MultiMC: package ID of this package
+	QString fileId;
+
+	/// MultiMC: version of this package
+	QString version;
+
+	/// MultiMC: dependency on a Minecraft version
+	QString dependsOnMinecraftVersion;
+
+	/// Mojang: used to version the Mojang version format
+	int minimumLauncherVersion = -1;
+
+	/// Mojang: version of Minecraft this is
+	QString minecraftVersion;
+
+	/// Mojang: class to launch Minecraft with
+	QString mainClass;
+
+	/// MultiMC: DEPRECATED class to launch legacy Minecraft with (ambed in a custom window)
+	QString appletClass;
+
+	/// Mojang: Minecraft launch arguments (may contain placeholders for variable substitution)
+	QString minecraftArguments;
+
+	/// Mojang: type of the Minecraft version
+	QString type;
+
+	/// Mojang: the time this version was actually released by Mojang
+	QDateTime m_releaseTime;
+
+	/// Mojang: the time this version was last updated by Mojang
+	QDateTime m_updateTime;
+
+	/// Mojang: DEPRECATED asset group to be used with Minecraft
+	QString assets;
+
+	/// MultiMC: list of tweaker mod arguments for launchwrapper
+	QStringList addTweakers;
+
+	/// Mojang: list of libraries to add to the version
+	QList<LibraryPtr> libraries;
+
+	/// MultiMC: list of attached traits of this version file - used to enable features
+	QSet<QString> traits;
+
+	/// MultiMC: list of jar mods added to this version
+	QList<JarmodPtr> jarMods;
+
+public:
+	// Mojang: list of 'downloads' - client jar, server jar, windows server exe, maybe more.
+	QMap <QString, std::shared_ptr<MojangDownloadInfo>> mojangDownloads;
+
+	// Mojang: extended asset index download information
+	std::shared_ptr<MojangAssetIndexInfo> mojangAssetIndex;
+};
+
+
diff --git a/libraries/logic/minecraft/VersionFilterData.cpp b/libraries/logic/minecraft/VersionFilterData.cpp
new file mode 100644
index 00000000..0c4a6e3d
--- /dev/null
+++ b/libraries/logic/minecraft/VersionFilterData.cpp
@@ -0,0 +1,75 @@
+#include "VersionFilterData.h"
+#include "ParseUtils.h"
+
+VersionFilterData g_VersionFilterData = VersionFilterData();
+
+VersionFilterData::VersionFilterData()
+{
+	// 1.3.*
+	auto libs13 =
+		QList<FMLlib>{{"argo-2.25.jar", "bb672829fde76cb163004752b86b0484bd0a7f4b", false},
+					  {"guava-12.0.1.jar", "b8e78b9af7bf45900e14c6f958486b6ca682195f", false},
+					  {"asm-all-4.0.jar", "98308890597acb64047f7e896638e0d98753ae82", false}};
+
+	fmlLibsMapping["1.3.2"] = libs13;
+
+	// 1.4.*
+	auto libs14 = QList<FMLlib>{
+		{"argo-2.25.jar", "bb672829fde76cb163004752b86b0484bd0a7f4b", false},
+		{"guava-12.0.1.jar", "b8e78b9af7bf45900e14c6f958486b6ca682195f", false},
+		{"asm-all-4.0.jar", "98308890597acb64047f7e896638e0d98753ae82", false},
+		{"bcprov-jdk15on-147.jar", "b6f5d9926b0afbde9f4dbe3db88c5247be7794bb", false}};
+
+	fmlLibsMapping["1.4"] = libs14;
+	fmlLibsMapping["1.4.1"] = libs14;
+	fmlLibsMapping["1.4.2"] = libs14;
+	fmlLibsMapping["1.4.3"] = libs14;
+	fmlLibsMapping["1.4.4"] = libs14;
+	fmlLibsMapping["1.4.5"] = libs14;
+	fmlLibsMapping["1.4.6"] = libs14;
+	fmlLibsMapping["1.4.7"] = libs14;
+
+	// 1.5
+	fmlLibsMapping["1.5"] = QList<FMLlib>{
+		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
+		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
+		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
+		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
+		{"deobfuscation_data_1.5.zip", "5f7c142d53776f16304c0bbe10542014abad6af8", false},
+		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
+
+	// 1.5.1
+	fmlLibsMapping["1.5.1"] = QList<FMLlib>{
+		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
+		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
+		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
+		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
+		{"deobfuscation_data_1.5.1.zip", "22e221a0d89516c1f721d6cab056a7e37471d0a6", false},
+		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
+
+	// 1.5.2
+	fmlLibsMapping["1.5.2"] = QList<FMLlib>{
+		{"argo-small-3.2.jar", "58912ea2858d168c50781f956fa5b59f0f7c6b51", false},
+		{"guava-14.0-rc3.jar", "931ae21fa8014c3ce686aaa621eae565fefb1a6a", false},
+		{"asm-all-4.1.jar", "054986e962b88d8660ae4566475658469595ef58", false},
+		{"bcprov-jdk15on-148.jar", "960dea7c9181ba0b17e8bab0c06a43f0a5f04e65", true},
+		{"deobfuscation_data_1.5.2.zip", "446e55cd986582c70fcf12cb27bc00114c5adfd9", false},
+		{"scala-library.jar", "458d046151ad179c85429ed7420ffb1eaf6ddf85", true}};
+
+	// don't use installers for those.
+	forgeInstallerBlacklist = QSet<QString>({"1.5.2"});
+	// these won't show up in version lists because they are extremely bad and dangerous
+	legacyBlacklist = QSet<QString>({"rd-160052"});
+	/*
+	 * nothing older than this will be accepted from Mojang servers
+	 * (these versions need to be tested by us first)
+	 */
+	legacyCutoffDate = timeFromS3Time("2013-06-25T15:08:56+02:00");
+	lwjglWhitelist =
+		QSet<QString>{"net.java.jinput:jinput",	 "net.java.jinput:jinput-platform",
+					  "net.java.jutils:jutils",	 "org.lwjgl.lwjgl:lwjgl",
+					  "org.lwjgl.lwjgl:lwjgl_util", "org.lwjgl.lwjgl:lwjgl-platform"};
+
+	// Version list magic
+	recommendedMinecraftVersion = "1.7.10";
+}
diff --git a/libraries/logic/minecraft/VersionFilterData.h b/libraries/logic/minecraft/VersionFilterData.h
new file mode 100644
index 00000000..f7d4ebe7
--- /dev/null
+++ b/libraries/logic/minecraft/VersionFilterData.h
@@ -0,0 +1,32 @@
+#pragma once
+#include <QMap>
+#include <QString>
+#include <QSet>
+#include <QDateTime>
+
+#include "multimc_logic_export.h"
+
+struct FMLlib
+{
+	QString filename;
+	QString checksum;
+	bool ours;
+};
+
+struct VersionFilterData
+{
+	VersionFilterData();
+	// mapping between minecraft versions and FML libraries required
+	QMap<QString, QList<FMLlib>> fmlLibsMapping;
+	// set of minecraft versions for which using forge installers is blacklisted
+	QSet<QString> forgeInstallerBlacklist;
+	// set of 'legacy' versions that will not show up in the version lists.
+	QSet<QString> legacyBlacklist;
+	// no new versions below this date will be accepted from Mojang servers
+	QDateTime legacyCutoffDate;
+	// Libraries that belong to LWJGL
+	QSet<QString> lwjglWhitelist;
+	// Currently recommended minecraft version
+	QString recommendedMinecraftVersion;
+};
+extern VersionFilterData MULTIMC_LOGIC_EXPORT g_VersionFilterData;
diff --git a/libraries/logic/minecraft/World.cpp b/libraries/logic/minecraft/World.cpp
new file mode 100644
index 00000000..6081a8ec
--- /dev/null
+++ b/libraries/logic/minecraft/World.cpp
@@ -0,0 +1,385 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QDir>
+#include <QString>
+#include <QDebug>
+#include <QSaveFile>
+#include "World.h"
+
+#include "GZip.h"
+#include <MMCZip.h>
+#include <FileSystem.h>
+#include <sstream>
+#include <io/stream_reader.h>
+#include <tag_string.h>
+#include <tag_primitive.h>
+#include <quazip.h>
+#include <quazipfile.h>
+#include <quazipdir.h>
+
+std::unique_ptr <nbt::tag_compound> parseLevelDat(QByteArray data)
+{
+	QByteArray output;
+	if(!GZip::unzip(data, output))
+	{
+		return nullptr;
+	}
+	std::istringstream foo(std::string(output.constData(), output.size()));
+	auto pair = nbt::io::read_compound(foo);
+
+	if(pair.first != "")
+		return nullptr;
+
+	if(pair.second == nullptr)
+		return nullptr;
+
+	return std::move(pair.second);
+}
+
+QByteArray serializeLevelDat(nbt::tag_compound * levelInfo)
+{
+	std::ostringstream s;
+	nbt::io::write_tag("", *levelInfo, s);
+	QByteArray val( s.str().data(), (int) s.str().size() );
+	return val;
+}
+
+QString getLevelDatFromFS(const QFileInfo &file)
+{
+	QDir worldDir(file.filePath());
+	if(!file.isDir() || !worldDir.exists("level.dat"))
+	{
+		return QString();
+	}
+	return worldDir.absoluteFilePath("level.dat");
+}
+
+QByteArray getLevelDatDataFromFS(const QFileInfo &file)
+{
+	auto fullFilePath = getLevelDatFromFS(file);
+	if(fullFilePath.isNull())
+	{
+		return QByteArray();
+	}
+	QFile f(fullFilePath);
+	if(!f.open(QIODevice::ReadOnly))
+	{
+		return QByteArray();
+	}
+	return f.readAll();
+}
+
+bool putLevelDatDataToFS(const QFileInfo &file, QByteArray & data)
+{
+	auto fullFilePath =  getLevelDatFromFS(file);
+	if(fullFilePath.isNull())
+	{
+		return false;
+	}
+	QSaveFile f(fullFilePath);
+	if(!f.open(QIODevice::WriteOnly))
+	{
+		return false;
+	}
+	QByteArray compressed;
+	if(!GZip::zip(data, compressed))
+	{
+		return false;
+	}
+	if(f.write(compressed) != compressed.size())
+	{
+		f.cancelWriting();
+		return false;
+	}
+	return f.commit();
+}
+
+World::World(const QFileInfo &file)
+{
+	repath(file);
+}
+
+void World::repath(const QFileInfo &file)
+{
+	m_containerFile = file;
+	m_folderName = file.fileName();
+	if(file.isFile() && file.suffix() == "zip")
+	{
+		readFromZip(file);
+	}
+	else if(file.isDir())
+	{
+		readFromFS(file);
+	}
+}
+
+void World::readFromFS(const QFileInfo &file)
+{
+	auto bytes = getLevelDatDataFromFS(file);
+	if(bytes.isEmpty())
+	{
+		is_valid = false;
+		return;
+	}
+	loadFromLevelDat(bytes);
+	levelDatTime = file.lastModified();
+}
+
+void World::readFromZip(const QFileInfo &file)
+{
+	QuaZip zip(file.absoluteFilePath());
+	is_valid = zip.open(QuaZip::mdUnzip);
+	if (!is_valid)
+	{
+		return;
+	}
+	auto location = MMCZip::findFileInZip(&zip, "level.dat");
+	is_valid = !location.isEmpty();
+	if (!is_valid)
+	{
+		return;
+	}
+	m_containerOffsetPath = location;
+	QuaZipFile zippedFile(&zip);
+	// read the install profile
+	is_valid = zip.setCurrentFile(location + "level.dat");
+	if (!is_valid)
+	{
+		return;
+	}
+	is_valid = zippedFile.open(QIODevice::ReadOnly);
+	QuaZipFileInfo64 levelDatInfo;
+	zippedFile.getFileInfo(&levelDatInfo);
+	auto modTime = levelDatInfo.getNTFSmTime();
+	if(!modTime.isValid())
+	{
+		modTime = levelDatInfo.dateTime;
+	}
+	levelDatTime = modTime;
+	if (!is_valid)
+	{
+		return;
+	}
+	loadFromLevelDat(zippedFile.readAll());
+	zippedFile.close();
+}
+
+bool World::install(const QString &to, const QString &name)
+{
+	auto finalPath = FS::PathCombine(to, FS::DirNameFromString(m_actualName, to));
+	if(!FS::ensureFolderPathExists(finalPath))
+	{
+		return false;
+	}
+	bool ok = false;
+	if(m_containerFile.isFile())
+	{
+		QuaZip zip(m_containerFile.absoluteFilePath());
+		if (!zip.open(QuaZip::mdUnzip))
+		{
+			return false;
+		}
+		ok = !MMCZip::extractSubDir(&zip, m_containerOffsetPath, finalPath).isEmpty();
+	}
+	else if(m_containerFile.isDir())
+	{
+		QString from = m_containerFile.filePath();
+		ok = FS::copy(from, finalPath)();
+	}
+
+	if(ok && !name.isEmpty() && m_actualName != name)
+	{
+		World newWorld(finalPath);
+		if(newWorld.isValid())
+		{
+			newWorld.rename(name);
+		}
+	}
+	return ok;
+}
+
+bool World::rename(const QString &newName)
+{
+	if(m_containerFile.isFile())
+	{
+		return false;
+	}
+
+	auto data = getLevelDatDataFromFS(m_containerFile);
+	if(data.isEmpty())
+	{
+		return false;
+	}
+
+	auto worldData = parseLevelDat(data);
+	if(!worldData)
+	{
+		return false;
+	}
+	auto &val = worldData->at("Data");
+	if(val.get_type() != nbt::tag_type::Compound)
+	{
+		return false;
+	}
+	auto &dataCompound = val.as<nbt::tag_compound>();
+	dataCompound.put("LevelName", nbt::value_initializer(newName.toUtf8().data()));
+	data = serializeLevelDat(worldData.get());
+
+	putLevelDatDataToFS(m_containerFile, data);
+
+	m_actualName = newName;
+
+	QDir parentDir(m_containerFile.absoluteFilePath());
+	parentDir.cdUp();
+	QFile container(m_containerFile.absoluteFilePath());
+	auto dirName = FS::DirNameFromString(m_actualName, parentDir.absolutePath());
+	container.rename(parentDir.absoluteFilePath(dirName));
+
+	return true;
+}
+
+static QString read_string (nbt::value& parent, const char * name, const QString & fallback = QString())
+{
+	try
+	{
+		auto &namedValue = parent.at(name);
+		if(namedValue.get_type() != nbt::tag_type::String)
+		{
+			return fallback;
+		}
+		auto & tag_str = namedValue.as<nbt::tag_string>();
+		return QString::fromStdString(tag_str.get());
+	}
+	catch(std::out_of_range e)
+	{
+		// fallback for old world formats
+		qWarning() << "String NBT tag" << name << "could not be found. Defaulting to" << fallback;
+		return fallback;
+	}
+	catch(std::bad_cast e)
+	{
+		// type mismatch
+		qWarning() << "NBT tag" << name << "could not be converted to string. Defaulting to" << fallback;
+		return fallback;
+	}
+};
+
+static int64_t read_long (nbt::value& parent, const char * name, const int64_t & fallback = 0)
+{
+	try
+	{
+		auto &namedValue = parent.at(name);
+		if(namedValue.get_type() != nbt::tag_type::Long)
+		{
+			return fallback;
+		}
+		auto & tag_str = namedValue.as<nbt::tag_long>();
+		return tag_str.get();
+	}
+	catch(std::out_of_range e)
+	{
+		// fallback for old world formats
+		qWarning() << "Long NBT tag" << name << "could not be found. Defaulting to" << fallback;
+		return fallback;
+	}
+	catch(std::bad_cast e)
+	{
+		// type mismatch
+		qWarning() << "NBT tag" << name << "could not be converted to long. Defaulting to" << fallback;
+		return fallback;
+	}
+};
+
+void World::loadFromLevelDat(QByteArray data)
+{
+	try
+	{
+		auto levelData = parseLevelDat(data);
+		if(!levelData)
+		{
+			is_valid = false;
+			return;
+		}
+
+		auto &val = levelData->at("Data");
+		is_valid = val.get_type() == nbt::tag_type::Compound;
+		if(!is_valid)
+			return;
+
+		m_actualName = read_string(val, "LevelName", m_folderName);
+
+
+		int64_t temp = read_long(val, "LastPlayed", 0);
+		if(temp == 0)
+		{
+			m_lastPlayed = levelDatTime;
+		}
+		else
+		{
+			m_lastPlayed = QDateTime::fromMSecsSinceEpoch(temp);
+		}
+
+		m_randomSeed = read_long(val, "RandomSeed", 0);
+
+		qDebug() << "World Name:" << m_actualName;
+		qDebug() << "Last Played:" << m_lastPlayed.toString();
+		qDebug() << "Seed:" << m_randomSeed;
+	}
+	catch (nbt::io::input_error e)
+	{
+		qWarning() << "Unable to load" << m_folderName << ":" << e.what();
+		is_valid = false;
+		return;
+	}
+}
+
+bool World::replace(World &with)
+{
+	if (!destroy())
+		return false;
+	bool success = FS::copy(with.m_containerFile.filePath(), m_containerFile.path())();
+	if (success)
+	{
+		m_folderName = with.m_folderName;
+		m_containerFile.refresh();
+	}
+	return success;
+}
+
+bool World::destroy()
+{
+	if(!is_valid) return false;
+	if (m_containerFile.isDir())
+	{
+		QDir d(m_containerFile.filePath());
+		return d.removeRecursively();
+	}
+	else if(m_containerFile.isFile())
+	{
+		QFile file(m_containerFile.absoluteFilePath());
+		return file.remove();
+	}
+	return true;
+}
+
+bool World::operator==(const World &other) const
+{
+	return is_valid == other.is_valid && folderName() == other.folderName();
+}
+bool World::strongCompare(const World &other) const
+{
+	return is_valid == other.is_valid && folderName() == other.folderName();
+}
diff --git a/libraries/logic/minecraft/World.h b/libraries/logic/minecraft/World.h
new file mode 100644
index 00000000..3cde5ea4
--- /dev/null
+++ b/libraries/logic/minecraft/World.h
@@ -0,0 +1,83 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QFileInfo>
+#include <QDateTime>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT World
+{
+public:
+	World(const QFileInfo &file);
+	QString folderName() const
+	{
+		return m_folderName;
+	}
+	QString name() const
+	{
+		return m_actualName;
+	}
+	QDateTime lastPlayed() const
+	{
+		return m_lastPlayed;
+	}
+	int64_t seed() const
+	{
+		return m_randomSeed;
+	}
+	bool isValid() const
+	{
+		return is_valid;
+	}
+	bool isOnFS() const
+	{
+		return m_containerFile.isDir();
+	}
+	QFileInfo container() const
+	{
+		return m_containerFile;
+	}
+	// delete all the files of this world
+	bool destroy();
+	// replace this world with a copy of the other
+	bool replace(World &with);
+	// change the world's filesystem path (used by world lists for *MAGIC* purposes)
+	void repath(const QFileInfo &file);
+
+	bool rename(const QString &to);
+	bool install(const QString &to, const QString &name= QString());
+
+	// WEAK compare operator - used for replacing worlds
+	bool operator==(const World &other) const;
+	bool strongCompare(const World &other) const;
+
+private:
+	void readFromZip(const QFileInfo &file);
+	void readFromFS(const QFileInfo &file);
+	void loadFromLevelDat(QByteArray data);
+
+protected:
+
+	QFileInfo m_containerFile;
+	QString m_containerOffsetPath;
+	QString m_folderName;
+	QString m_actualName;
+	QDateTime levelDatTime;
+	QDateTime m_lastPlayed;
+	int64_t m_randomSeed = 0;
+	bool is_valid = false;
+};
diff --git a/libraries/logic/minecraft/WorldList.cpp b/libraries/logic/minecraft/WorldList.cpp
new file mode 100644
index 00000000..42c8a3e6
--- /dev/null
+++ b/libraries/logic/minecraft/WorldList.cpp
@@ -0,0 +1,355 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WorldList.h"
+#include <FileSystem.h>
+#include <QMimeData>
+#include <QUrl>
+#include <QUuid>
+#include <QString>
+#include <QFileSystemWatcher>
+#include <QDebug>
+
+WorldList::WorldList(const QString &dir)
+	: QAbstractListModel(), m_dir(dir)
+{
+	FS::ensureFolderPathExists(m_dir.absolutePath());
+	m_dir.setFilter(QDir::Readable | QDir::NoDotAndDotDot | QDir::Files | QDir::Dirs |
+					QDir::NoSymLinks);
+	m_dir.setSorting(QDir::Name | QDir::IgnoreCase | QDir::LocaleAware);
+	m_watcher = new QFileSystemWatcher(this);
+	is_watching = false;
+	connect(m_watcher, SIGNAL(directoryChanged(QString)), this,
+			SLOT(directoryChanged(QString)));
+}
+
+void WorldList::startWatching()
+{
+	update();
+	is_watching = m_watcher->addPath(m_dir.absolutePath());
+	if (is_watching)
+	{
+		qDebug() << "Started watching " << m_dir.absolutePath();
+	}
+	else
+	{
+		qDebug() << "Failed to start watching " << m_dir.absolutePath();
+	}
+}
+
+void WorldList::stopWatching()
+{
+	is_watching = !m_watcher->removePath(m_dir.absolutePath());
+	if (!is_watching)
+	{
+		qDebug() << "Stopped watching " << m_dir.absolutePath();
+	}
+	else
+	{
+		qDebug() << "Failed to stop watching " << m_dir.absolutePath();
+	}
+}
+
+bool WorldList::update()
+{
+	if (!isValid())
+		return false;
+
+	QList<World> newWorlds;
+	m_dir.refresh();
+	auto folderContents = m_dir.entryInfoList();
+	// if there are any untracked files...
+	for (QFileInfo entry : folderContents)
+	{
+		if(!entry.isDir())
+			continue;
+
+		World w(entry);
+		if(w.isValid())
+		{
+			newWorlds.append(w);
+		}
+	}
+	beginResetModel();
+	worlds.swap(newWorlds);
+	endResetModel();
+	return true;
+}
+
+void WorldList::directoryChanged(QString path)
+{
+	update();
+}
+
+bool WorldList::isValid()
+{
+	return m_dir.exists() && m_dir.isReadable();
+}
+
+bool WorldList::deleteWorld(int index)
+{
+	if (index >= worlds.size() || index < 0)
+		return false;
+	World &m = worlds[index];
+	if (m.destroy())
+	{
+		beginRemoveRows(QModelIndex(), index, index);
+		worlds.removeAt(index);
+		endRemoveRows();
+		emit changed();
+		return true;
+	}
+	return false;
+}
+
+bool WorldList::deleteWorlds(int first, int last)
+{
+	for (int i = first; i <= last; i++)
+	{
+		World &m = worlds[i];
+		m.destroy();
+	}
+	beginRemoveRows(QModelIndex(), first, last);
+	worlds.erase(worlds.begin() + first, worlds.begin() + last + 1);
+	endRemoveRows();
+	emit changed();
+	return true;
+}
+
+int WorldList::columnCount(const QModelIndex &parent) const
+{
+	return 2;
+}
+
+QVariant WorldList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	int row = index.row();
+	int column = index.column();
+
+	if (row < 0 || row >= worlds.size())
+		return QVariant();
+
+	auto & world = worlds[row];
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (column)
+		{
+		case NameColumn:
+			return world.name();
+
+		case LastPlayedColumn:
+			return world.lastPlayed();
+
+		default:
+			return QVariant();
+		}
+
+	case Qt::ToolTipRole:
+	{
+		return world.folderName();
+	}
+	case ObjectRole:
+	{
+		return QVariant::fromValue<void *>((void *)&world);
+	}
+	case FolderRole:
+	{
+		return QDir::toNativeSeparators(dir().absoluteFilePath(world.folderName()));
+	}
+	case SeedRole:
+	{
+		return qVariantFromValue<qlonglong>(world.seed());
+	}
+	case NameRole:
+	{
+		return world.name();
+	}
+	case LastPlayedRole:
+	{
+		return world.lastPlayed();
+	}
+	default:
+		return QVariant();
+	}
+}
+
+QVariant WorldList::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (section)
+		{
+		case NameColumn:
+			return tr("Name");
+		case LastPlayedColumn:
+			return tr("Last Played");
+		default:
+			return QVariant();
+		}
+
+	case Qt::ToolTipRole:
+		switch (section)
+		{
+		case NameColumn:
+			return tr("The name of the world.");
+		case LastPlayedColumn:
+			return tr("Date and time the world was last played.");
+		default:
+			return QVariant();
+		}
+	default:
+		return QVariant();
+	}
+	return QVariant();
+}
+
+QStringList WorldList::mimeTypes() const
+{
+	QStringList types;
+	types << "text/uri-list";
+	return types;
+}
+
+class WorldMimeData : public QMimeData
+{
+Q_OBJECT
+
+public:
+	WorldMimeData(QList<World> worlds)
+	{
+		m_worlds = worlds;
+
+	}
+	QStringList formats() const
+	{
+		return QMimeData::formats() << "text/uri-list";
+	}
+
+protected:
+	QVariant retrieveData(const QString &mimetype, QVariant::Type type) const
+	{
+		QList<QUrl> urls;
+		for(auto &world: m_worlds)
+		{
+			if(!world.isValid() || !world.isOnFS())
+				continue;
+			QString worldPath = world.container().absoluteFilePath();
+			qDebug() << worldPath;
+			urls.append(QUrl::fromLocalFile(worldPath));
+		}
+		const_cast<WorldMimeData*>(this)->setUrls(urls);
+		return QMimeData::retrieveData(mimetype, type);
+	}
+private:
+	QList<World> m_worlds;
+};
+
+QMimeData *WorldList::mimeData(const QModelIndexList &indexes) const
+{
+	if (indexes.size() == 0)
+		return new QMimeData();
+
+	QList<World> worlds;
+	for(auto idx : indexes)
+	{
+		if(idx.column() != 0)
+			continue;
+		int row = idx.row();
+		if (row < 0 || row >= this->worlds.size())
+			continue;
+		worlds.append(this->worlds[row]);
+	}
+	if(!worlds.size())
+	{
+		return new QMimeData();
+	}
+	return new WorldMimeData(worlds);
+}
+
+Qt::ItemFlags WorldList::flags(const QModelIndex &index) const
+{
+	Qt::ItemFlags defaultFlags = QAbstractListModel::flags(index);
+	if (index.isValid())
+		return Qt::ItemIsUserCheckable | Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled |
+			   defaultFlags;
+	else
+		return Qt::ItemIsDropEnabled | defaultFlags;
+}
+
+Qt::DropActions WorldList::supportedDragActions() const
+{
+	// move to other mod lists or VOID
+	return Qt::MoveAction;
+}
+
+Qt::DropActions WorldList::supportedDropActions() const
+{
+	// copy from outside, move from within and other mod lists
+	return Qt::CopyAction | Qt::MoveAction;
+}
+
+void WorldList::installWorld(QFileInfo filename)
+{
+	qDebug() << "installing: " << filename.absoluteFilePath();
+	World w(filename);
+	if(!w.isValid())
+	{
+		return;
+	}
+	w.install(m_dir.absolutePath());
+}
+
+bool WorldList::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column,
+							 const QModelIndex &parent)
+{
+	if (action == Qt::IgnoreAction)
+		return true;
+	// check if the action is supported
+	if (!data || !(action & supportedDropActions()))
+		return false;
+	// files dropped from outside?
+	if (data->hasUrls())
+	{
+		bool was_watching = is_watching;
+		if (was_watching)
+			stopWatching();
+		auto urls = data->urls();
+		for (auto url : urls)
+		{
+			// only local files may be dropped...
+			if (!url.isLocalFile())
+				continue;
+			QString filename = url.toLocalFile();
+
+			QFileInfo worldInfo(filename);
+
+			if(!m_dir.entryInfoList().contains(worldInfo))
+			{
+				installWorld(worldInfo);
+			}
+		}
+		if (was_watching)
+			startWatching();
+		return true;
+	}
+	return false;
+}
+
+#include "WorldList.moc"
diff --git a/libraries/logic/minecraft/WorldList.h b/libraries/logic/minecraft/WorldList.h
new file mode 100644
index 00000000..34b30e9c
--- /dev/null
+++ b/libraries/logic/minecraft/WorldList.h
@@ -0,0 +1,125 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QList>
+#include <QString>
+#include <QDir>
+#include <QAbstractListModel>
+#include <QMimeData>
+#include "minecraft/World.h"
+
+#include "multimc_logic_export.h"
+
+class QFileSystemWatcher;
+
+class MULTIMC_LOGIC_EXPORT WorldList : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	enum Columns
+	{
+		NameColumn,
+		LastPlayedColumn
+	};
+
+	enum Roles
+	{
+		ObjectRole = Qt::UserRole + 1,
+		FolderRole,
+		SeedRole,
+		NameRole,
+		LastPlayedRole
+	};
+
+	WorldList(const QString &dir);
+
+	virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
+
+	virtual int rowCount(const QModelIndex &parent = QModelIndex()) const
+	{
+		return size();
+	};
+	virtual QVariant headerData(int section, Qt::Orientation orientation,
+								int role = Qt::DisplayRole) const;
+	virtual int columnCount(const QModelIndex &parent) const;
+
+	size_t size() const
+	{
+		return worlds.size();
+	};
+	bool empty() const
+	{
+		return size() == 0;
+	}
+	World &operator[](size_t index)
+	{
+		return worlds[index];
+	}
+
+	/// Reloads the mod list and returns true if the list changed.
+	virtual bool update();
+
+	/// Install a world from location
+	void installWorld(QFileInfo filename);
+
+	/// Deletes the mod at the given index.
+	virtual bool deleteWorld(int index);
+
+	/// Deletes all the selected mods
+	virtual bool deleteWorlds(int first, int last);
+
+	/// flags, mostly to support drag&drop
+	virtual Qt::ItemFlags flags(const QModelIndex &index) const;
+	/// get data for drag action
+	virtual QMimeData *mimeData(const QModelIndexList &indexes) const;
+	/// get the supported mime types
+	virtual QStringList mimeTypes() const;
+	/// process data from drop action
+	virtual bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent);
+	/// what drag actions do we support?
+	virtual Qt::DropActions supportedDragActions() const;
+
+	/// what drop actions do we support?
+	virtual Qt::DropActions supportedDropActions() const;
+
+	void startWatching();
+	void stopWatching();
+
+	virtual bool isValid();
+
+	QDir dir() const
+	{
+		return m_dir;
+	}
+
+	const QList<World> &allWorlds() const
+	{
+		return worlds;
+	}
+
+private slots:
+	void directoryChanged(QString path);
+
+signals:
+	void changed();
+
+protected:
+	QFileSystemWatcher *m_watcher;
+	bool is_watching;
+	QDir m_dir;
+	QList<World> worlds;
+};
diff --git a/libraries/logic/minecraft/auth/AuthSession.cpp b/libraries/logic/minecraft/auth/AuthSession.cpp
new file mode 100644
index 00000000..8758bfbd
--- /dev/null
+++ b/libraries/logic/minecraft/auth/AuthSession.cpp
@@ -0,0 +1,30 @@
+#include "AuthSession.h"
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QStringList>
+
+QString AuthSession::serializeUserProperties()
+{
+	QJsonObject userAttrs;
+	for (auto key : u.properties.keys())
+	{
+		auto array = QJsonArray::fromStringList(u.properties.values(key));
+		userAttrs.insert(key, array);
+	}
+	QJsonDocument value(userAttrs);
+	return value.toJson(QJsonDocument::Compact);
+
+}
+
+bool AuthSession::MakeOffline(QString offline_playername)
+{
+	if (status != PlayableOffline && status != PlayableOnline)
+	{
+		return false;
+	}
+	session = "-";
+	player_name = offline_playername;
+	status = PlayableOffline;
+	return true;
+}
diff --git a/libraries/logic/minecraft/auth/AuthSession.h b/libraries/logic/minecraft/auth/AuthSession.h
new file mode 100644
index 00000000..dede90a9
--- /dev/null
+++ b/libraries/logic/minecraft/auth/AuthSession.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#include <QString>
+#include <QMultiMap>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+struct User
+{
+	QString id;
+	QMultiMap<QString, QString> properties;
+};
+
+struct MULTIMC_LOGIC_EXPORT AuthSession
+{
+	bool MakeOffline(QString offline_playername);
+
+	QString serializeUserProperties();
+
+	enum Status
+	{
+		Undetermined,
+		RequiresPassword,
+		PlayableOffline,
+		PlayableOnline
+	} status = Undetermined;
+
+	User u;
+
+	// client token
+	QString client_token;
+	// account user name
+	QString username;
+	// combined session ID
+	QString session;
+	// volatile auth token
+	QString access_token;
+	// profile name
+	QString player_name;
+	// profile ID
+	QString uuid;
+	// 'legacy' or 'mojang', depending on account type
+	QString user_type;
+	// Did the auth server reply?
+	bool auth_server_online = false;
+	// Did the user request online mode?
+	bool wants_online = true;
+};
+
+typedef std::shared_ptr<AuthSession> AuthSessionPtr;
diff --git a/libraries/logic/minecraft/auth/MojangAccount.cpp b/libraries/logic/minecraft/auth/MojangAccount.cpp
new file mode 100644
index 00000000..69a24c09
--- /dev/null
+++ b/libraries/logic/minecraft/auth/MojangAccount.cpp
@@ -0,0 +1,278 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MojangAccount.h"
+#include "flows/RefreshTask.h"
+#include "flows/AuthenticateTask.h"
+
+#include <QUuid>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QRegExp>
+#include <QStringList>
+#include <QJsonDocument>
+
+#include <QDebug>
+
+MojangAccountPtr MojangAccount::loadFromJson(const QJsonObject &object)
+{
+	// The JSON object must at least have a username for it to be valid.
+	if (!object.value("username").isString())
+	{
+		qCritical() << "Can't load Mojang account info from JSON object. Username field is "
+						"missing or of the wrong type.";
+		return nullptr;
+	}
+
+	QString username = object.value("username").toString("");
+	QString clientToken = object.value("clientToken").toString("");
+	QString accessToken = object.value("accessToken").toString("");
+
+	QJsonArray profileArray = object.value("profiles").toArray();
+	if (profileArray.size() < 1)
+	{
+		qCritical() << "Can't load Mojang account with username \"" << username
+					 << "\". No profiles found.";
+		return nullptr;
+	}
+
+	QList<AccountProfile> profiles;
+	for (QJsonValue profileVal : profileArray)
+	{
+		QJsonObject profileObject = profileVal.toObject();
+		QString id = profileObject.value("id").toString("");
+		QString name = profileObject.value("name").toString("");
+		bool legacy = profileObject.value("legacy").toBool(false);
+		if (id.isEmpty() || name.isEmpty())
+		{
+			qWarning() << "Unable to load a profile because it was missing an ID or a name.";
+			continue;
+		}
+		profiles.append({id, name, legacy});
+	}
+
+	MojangAccountPtr account(new MojangAccount());
+	if (object.value("user").isObject())
+	{
+		User u;
+		QJsonObject userStructure = object.value("user").toObject();
+		u.id = userStructure.value("id").toString();
+		/*
+		QJsonObject propMap = userStructure.value("properties").toObject();
+		for(auto key: propMap.keys())
+		{
+			auto values = propMap.operator[](key).toArray();
+			for(auto value: values)
+				u.properties.insert(key, value.toString());
+		}
+		*/
+		account->m_user = u;
+	}
+	account->m_username = username;
+	account->m_clientToken = clientToken;
+	account->m_accessToken = accessToken;
+	account->m_profiles = profiles;
+
+	// Get the currently selected profile.
+	QString currentProfile = object.value("activeProfile").toString("");
+	if (!currentProfile.isEmpty())
+		account->setCurrentProfile(currentProfile);
+
+	return account;
+}
+
+MojangAccountPtr MojangAccount::createFromUsername(const QString &username)
+{
+	MojangAccountPtr account(new MojangAccount());
+	account->m_clientToken = QUuid::createUuid().toString().remove(QRegExp("[{}-]"));
+	account->m_username = username;
+	return account;
+}
+
+QJsonObject MojangAccount::saveToJson() const
+{
+	QJsonObject json;
+	json.insert("username", m_username);
+	json.insert("clientToken", m_clientToken);
+	json.insert("accessToken", m_accessToken);
+
+	QJsonArray profileArray;
+	for (AccountProfile profile : m_profiles)
+	{
+		QJsonObject profileObj;
+		profileObj.insert("id", profile.id);
+		profileObj.insert("name", profile.name);
+		profileObj.insert("legacy", profile.legacy);
+		profileArray.append(profileObj);
+	}
+	json.insert("profiles", profileArray);
+
+	QJsonObject userStructure;
+	{
+		userStructure.insert("id", m_user.id);
+		/*
+		QJsonObject userAttrs;
+		for(auto key: m_user.properties.keys())
+		{
+			auto array = QJsonArray::fromStringList(m_user.properties.values(key));
+			userAttrs.insert(key, array);
+		}
+		userStructure.insert("properties", userAttrs);
+		*/
+	}
+	json.insert("user", userStructure);
+
+	if (m_currentProfile != -1)
+		json.insert("activeProfile", currentProfile()->id);
+
+	return json;
+}
+
+bool MojangAccount::setCurrentProfile(const QString &profileId)
+{
+	for (int i = 0; i < m_profiles.length(); i++)
+	{
+		if (m_profiles[i].id == profileId)
+		{
+			m_currentProfile = i;
+			return true;
+		}
+	}
+	return false;
+}
+
+const AccountProfile *MojangAccount::currentProfile() const
+{
+	if (m_currentProfile == -1)
+		return nullptr;
+	return &m_profiles[m_currentProfile];
+}
+
+AccountStatus MojangAccount::accountStatus() const
+{
+	if (m_accessToken.isEmpty())
+		return NotVerified;
+	else
+		return Verified;
+}
+
+std::shared_ptr<YggdrasilTask> MojangAccount::login(AuthSessionPtr session,
+													QString password)
+{
+	Q_ASSERT(m_currentTask.get() == nullptr);
+
+	// take care of the true offline status
+	if (accountStatus() == NotVerified && password.isEmpty())
+	{
+		if (session)
+		{
+			session->status = AuthSession::RequiresPassword;
+			fillSession(session);
+		}
+		return nullptr;
+	}
+
+	if (password.isEmpty())
+	{
+		m_currentTask.reset(new RefreshTask(this));
+	}
+	else
+	{
+		m_currentTask.reset(new AuthenticateTask(this, password));
+	}
+	m_currentTask->assignSession(session);
+
+	connect(m_currentTask.get(), SIGNAL(succeeded()), SLOT(authSucceeded()));
+	connect(m_currentTask.get(), SIGNAL(failed(QString)), SLOT(authFailed(QString)));
+	return m_currentTask;
+}
+
+void MojangAccount::authSucceeded()
+{
+	auto session = m_currentTask->getAssignedSession();
+	if (session)
+	{
+		session->status =
+			session->wants_online ? AuthSession::PlayableOnline : AuthSession::PlayableOffline;
+		fillSession(session);
+		session->auth_server_online = true;
+	}
+	m_currentTask.reset();
+	emit changed();
+}
+
+void MojangAccount::authFailed(QString reason)
+{
+	auto session = m_currentTask->getAssignedSession();
+	// This is emitted when the yggdrasil tasks time out or are cancelled.
+	// -> we treat the error as no-op
+	if (m_currentTask->state() == YggdrasilTask::STATE_FAILED_SOFT)
+	{
+		if (session)
+		{
+			session->status = accountStatus() == Verified ? AuthSession::PlayableOffline
+														  : AuthSession::RequiresPassword;
+			session->auth_server_online = false;
+			fillSession(session);
+		}
+	}
+	else
+	{
+		m_accessToken = QString();
+		emit changed();
+		if (session)
+		{
+			session->status = AuthSession::RequiresPassword;
+			session->auth_server_online = true;
+			fillSession(session);
+		}
+	}
+	m_currentTask.reset();
+}
+
+void MojangAccount::fillSession(AuthSessionPtr session)
+{
+	// the user name. you have to have an user name
+	session->username = m_username;
+	// volatile auth token
+	session->access_token = m_accessToken;
+	// the semi-permanent client token
+	session->client_token = m_clientToken;
+	if (currentProfile())
+	{
+		// profile name
+		session->player_name = currentProfile()->name;
+		// profile ID
+		session->uuid = currentProfile()->id;
+		// 'legacy' or 'mojang', depending on account type
+		session->user_type = currentProfile()->legacy ? "legacy" : "mojang";
+		if (!session->access_token.isEmpty())
+		{
+			session->session = "token:" + m_accessToken + ":" + m_profiles[m_currentProfile].id;
+		}
+		else
+		{
+			session->session = "-";
+		}
+	}
+	else
+	{
+		session->player_name = "Player";
+		session->session = "-";
+	}
+	session->u = user();
+}
diff --git a/libraries/logic/minecraft/auth/MojangAccount.h b/libraries/logic/minecraft/auth/MojangAccount.h
new file mode 100644
index 00000000..2de0c19c
--- /dev/null
+++ b/libraries/logic/minecraft/auth/MojangAccount.h
@@ -0,0 +1,173 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QString>
+#include <QList>
+#include <QJsonObject>
+#include <QPair>
+#include <QMap>
+
+#include <memory>
+#include "AuthSession.h"
+
+#include "multimc_logic_export.h"
+
+class Task;
+class YggdrasilTask;
+class MojangAccount;
+
+typedef std::shared_ptr<MojangAccount> MojangAccountPtr;
+Q_DECLARE_METATYPE(MojangAccountPtr)
+
+/**
+ * A profile within someone's Mojang account.
+ *
+ * Currently, the profile system has not been implemented by Mojang yet,
+ * but we might as well add some things for it in MultiMC right now so
+ * we don't have to rip the code to pieces to add it later.
+ */
+struct AccountProfile
+{
+	QString id;
+	QString name;
+	bool legacy;
+};
+
+enum AccountStatus
+{
+	NotVerified,
+	Verified
+};
+
+/**
+ * Object that stores information about a certain Mojang account.
+ *
+ * Said information may include things such as that account's username, client token, and access
+ * token if the user chose to stay logged in.
+ */
+class MULTIMC_LOGIC_EXPORT MojangAccount : public QObject
+{
+	Q_OBJECT
+public: /* construction */
+	//! Do not copy accounts. ever.
+	explicit MojangAccount(const MojangAccount &other, QObject *parent) = delete;
+
+	//! Default constructor
+	explicit MojangAccount(QObject *parent = 0) : QObject(parent) {};
+
+	//! Creates an empty account for the specified user name.
+	static MojangAccountPtr createFromUsername(const QString &username);
+
+	//! Loads a MojangAccount from the given JSON object.
+	static MojangAccountPtr loadFromJson(const QJsonObject &json);
+
+	//! Saves a MojangAccount to a JSON object and returns it.
+	QJsonObject saveToJson() const;
+
+public: /* manipulation */
+		/**
+	 * Sets the currently selected profile to the profile with the given ID string.
+	 * If profileId is not in the list of available profiles, the function will simply return
+	 * false.
+	 */
+	bool setCurrentProfile(const QString &profileId);
+
+	/**
+	 * Attempt to login. Empty password means we use the token.
+	 * If the attempt fails because we already are performing some task, it returns false.
+	 */
+	std::shared_ptr<YggdrasilTask> login(AuthSessionPtr session,
+										 QString password = QString());
+
+public: /* queries */
+	const QString &username() const
+	{
+		return m_username;
+	}
+
+	const QString &clientToken() const
+	{
+		return m_clientToken;
+	}
+
+	const QString &accessToken() const
+	{
+		return m_accessToken;
+	}
+
+	const QList<AccountProfile> &profiles() const
+	{
+		return m_profiles;
+	}
+
+	const User &user()
+	{
+		return m_user;
+	}
+
+	//! Returns the currently selected profile (if none, returns nullptr)
+	const AccountProfile *currentProfile() const;
+
+	//! Returns whether the account is NotVerified, Verified or Online
+	AccountStatus accountStatus() const;
+
+signals:
+	/**
+	 * This signal is emitted when the account changes
+	 */
+	void changed();
+
+	// TODO: better signalling for the various possible state changes - especially errors
+
+protected: /* variables */
+	QString m_username;
+
+	// Used to identify the client - the user can have multiple clients for the same account
+	// Think: different launchers, all connecting to the same account/profile
+	QString m_clientToken;
+
+	// Blank if not logged in.
+	QString m_accessToken;
+
+	// Index of the selected profile within the list of available
+	// profiles. -1 if nothing is selected.
+	int m_currentProfile = -1;
+
+	// List of available profiles.
+	QList<AccountProfile> m_profiles;
+
+	// the user structure, whatever it is.
+	User m_user;
+
+	// current task we are executing here
+	std::shared_ptr<YggdrasilTask> m_currentTask;
+
+private
+slots:
+	void authSucceeded();
+	void authFailed(QString reason);
+
+private:
+	void fillSession(AuthSessionPtr session);
+
+public:
+	friend class YggdrasilTask;
+	friend class AuthenticateTask;
+	friend class ValidateTask;
+	friend class RefreshTask;
+};
diff --git a/libraries/logic/minecraft/auth/MojangAccountList.cpp b/libraries/logic/minecraft/auth/MojangAccountList.cpp
new file mode 100644
index 00000000..26cbc81a
--- /dev/null
+++ b/libraries/logic/minecraft/auth/MojangAccountList.cpp
@@ -0,0 +1,427 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "MojangAccountList.h"
+#include "MojangAccount.h"
+
+#include <QIODevice>
+#include <QFile>
+#include <QTextStream>
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QJsonObject>
+#include <QJsonParseError>
+#include <QDir>
+
+#include <QDebug>
+
+#include <FileSystem.h>
+
+#define ACCOUNT_LIST_FORMAT_VERSION 2
+
+MojangAccountList::MojangAccountList(QObject *parent) : QAbstractListModel(parent)
+{
+}
+
+MojangAccountPtr MojangAccountList::findAccount(const QString &username) const
+{
+	for (int i = 0; i < count(); i++)
+	{
+		MojangAccountPtr account = at(i);
+		if (account->username() == username)
+			return account;
+	}
+	return nullptr;
+}
+
+const MojangAccountPtr MojangAccountList::at(int i) const
+{
+	return MojangAccountPtr(m_accounts.at(i));
+}
+
+void MojangAccountList::addAccount(const MojangAccountPtr account)
+{
+	beginResetModel();
+	connect(account.get(), SIGNAL(changed()), SLOT(accountChanged()));
+	m_accounts.append(account);
+	endResetModel();
+	onListChanged();
+}
+
+void MojangAccountList::removeAccount(const QString &username)
+{
+	beginResetModel();
+	for (auto account : m_accounts)
+	{
+		if (account->username() == username)
+		{
+			m_accounts.removeOne(account);
+			return;
+		}
+	}
+	endResetModel();
+	onListChanged();
+}
+
+void MojangAccountList::removeAccount(QModelIndex index)
+{
+	beginResetModel();
+	m_accounts.removeAt(index.row());
+	endResetModel();
+	onListChanged();
+}
+
+MojangAccountPtr MojangAccountList::activeAccount() const
+{
+	return m_activeAccount;
+}
+
+void MojangAccountList::setActiveAccount(const QString &username)
+{
+	beginResetModel();
+	if (username.isEmpty())
+	{
+		m_activeAccount = nullptr;
+	}
+	else
+	{
+		for (MojangAccountPtr account : m_accounts)
+		{
+			if (account->username() == username)
+				m_activeAccount = account;
+		}
+	}
+	endResetModel();
+	onActiveChanged();
+}
+
+void MojangAccountList::accountChanged()
+{
+	// the list changed. there is no doubt.
+	onListChanged();
+}
+
+void MojangAccountList::onListChanged()
+{
+	if (m_autosave)
+		// TODO: Alert the user if this fails.
+		saveList();
+
+	emit listChanged();
+}
+
+void MojangAccountList::onActiveChanged()
+{
+	if (m_autosave)
+		saveList();
+
+	emit activeAccountChanged();
+}
+
+int MojangAccountList::count() const
+{
+	return m_accounts.count();
+}
+
+QVariant MojangAccountList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	MojangAccountPtr account = at(index.row());
+
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (index.column())
+		{
+		case NameColumn:
+			return account->username();
+
+		default:
+			return QVariant();
+		}
+
+	case Qt::ToolTipRole:
+		return account->username();
+
+	case PointerRole:
+		return qVariantFromValue(account);
+
+	case Qt::CheckStateRole:
+		switch (index.column())
+		{
+		case ActiveColumn:
+			return account == m_activeAccount;
+		}
+
+	default:
+		return QVariant();
+	}
+}
+
+QVariant MojangAccountList::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (section)
+		{
+		case ActiveColumn:
+			return tr("Active?");
+
+		case NameColumn:
+			return tr("Name");
+
+		default:
+			return QVariant();
+		}
+
+	case Qt::ToolTipRole:
+		switch (section)
+		{
+		case NameColumn:
+			return tr("The name of the version.");
+
+		default:
+			return QVariant();
+		}
+
+	default:
+		return QVariant();
+	}
+}
+
+int MojangAccountList::rowCount(const QModelIndex &parent) const
+{
+	// Return count
+	return count();
+}
+
+int MojangAccountList::columnCount(const QModelIndex &parent) const
+{
+	return 2;
+}
+
+Qt::ItemFlags MojangAccountList::flags(const QModelIndex &index) const
+{
+	if (index.row() < 0 || index.row() >= rowCount(index) || !index.isValid())
+	{
+		return Qt::NoItemFlags;
+	}
+
+	return Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+}
+
+bool MojangAccountList::setData(const QModelIndex &index, const QVariant &value, int role)
+{
+	if (index.row() < 0 || index.row() >= rowCount(index) || !index.isValid())
+	{
+		return false;
+	}
+
+	if(role == Qt::CheckStateRole)
+	{
+		if(value == Qt::Checked)
+		{
+			MojangAccountPtr account = this->at(index.row());
+			this->setActiveAccount(account->username());
+		}
+	}
+
+	emit dataChanged(index, index);
+	return true;
+}
+
+void MojangAccountList::updateListData(QList<MojangAccountPtr> versions)
+{
+	beginResetModel();
+	m_accounts = versions;
+	endResetModel();
+}
+
+bool MojangAccountList::loadList(const QString &filePath)
+{
+	QString path = filePath;
+	if (path.isEmpty())
+		path = m_listFilePath;
+	if (path.isEmpty())
+	{
+		qCritical() << "Can't load Mojang account list. No file path given and no default set.";
+		return false;
+	}
+
+	QFile file(path);
+
+	// Try to open the file and fail if we can't.
+	// TODO: We should probably report this error to the user.
+	if (!file.open(QIODevice::ReadOnly))
+	{
+		qCritical() << QString("Failed to read the account list file (%1).").arg(path).toUtf8();
+		return false;
+	}
+
+	// Read the file and close it.
+	QByteArray jsonData = file.readAll();
+	file.close();
+
+	QJsonParseError parseError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &parseError);
+
+	// Fail if the JSON is invalid.
+	if (parseError.error != QJsonParseError::NoError)
+	{
+		qCritical() << QString("Failed to parse account list file: %1 at offset %2")
+							.arg(parseError.errorString(), QString::number(parseError.offset))
+							.toUtf8();
+		return false;
+	}
+
+	// Make sure the root is an object.
+	if (!jsonDoc.isObject())
+	{
+		qCritical() << "Invalid account list JSON: Root should be an array.";
+		return false;
+	}
+
+	QJsonObject root = jsonDoc.object();
+
+	// Make sure the format version matches.
+	if (root.value("formatVersion").toVariant().toInt() != ACCOUNT_LIST_FORMAT_VERSION)
+	{
+		QString newName = "accounts-old.json";
+		qWarning() << "Format version mismatch when loading account list. Existing one will be renamed to"
+					<< newName;
+
+		// Attempt to rename the old version.
+		file.rename(newName);
+		return false;
+	}
+
+	// Now, load the accounts array.
+	beginResetModel();
+	QJsonArray accounts = root.value("accounts").toArray();
+	for (QJsonValue accountVal : accounts)
+	{
+		QJsonObject accountObj = accountVal.toObject();
+		MojangAccountPtr account = MojangAccount::loadFromJson(accountObj);
+		if (account.get() != nullptr)
+		{
+			connect(account.get(), SIGNAL(changed()), SLOT(accountChanged()));
+			m_accounts.append(account);
+		}
+		else
+		{
+			qWarning() << "Failed to load an account.";
+		}
+	}
+	// Load the active account.
+	m_activeAccount = findAccount(root.value("activeAccount").toString(""));
+	endResetModel();
+	return true;
+}
+
+bool MojangAccountList::saveList(const QString &filePath)
+{
+	QString path(filePath);
+	if (path.isEmpty())
+		path = m_listFilePath;
+	if (path.isEmpty())
+	{
+		qCritical() << "Can't save Mojang account list. No file path given and no default set.";
+		return false;
+	}
+
+	// make sure the parent folder exists
+	if(!FS::ensureFilePathExists(path))
+		return false;
+
+	// make sure the file wasn't overwritten with a folder before (fixes a bug)
+	QFileInfo finfo(path);
+	if(finfo.isDir())
+	{
+		QDir badDir(path);
+		badDir.removeRecursively();
+	}
+
+	qDebug() << "Writing account list to" << path;
+
+	qDebug() << "Building JSON data structure.";
+	// Build the JSON document to write to the list file.
+	QJsonObject root;
+
+	root.insert("formatVersion", ACCOUNT_LIST_FORMAT_VERSION);
+
+	// Build a list of accounts.
+	qDebug() << "Building account array.";
+	QJsonArray accounts;
+	for (MojangAccountPtr account : m_accounts)
+	{
+		QJsonObject accountObj = account->saveToJson();
+		accounts.append(accountObj);
+	}
+
+	// Insert the account list into the root object.
+	root.insert("accounts", accounts);
+
+	if(m_activeAccount)
+	{
+		// Save the active account.
+		root.insert("activeAccount", m_activeAccount->username());
+	}
+
+	// Create a JSON document object to convert our JSON to bytes.
+	QJsonDocument doc(root);
+
+	// Now that we're done building the JSON object, we can write it to the file.
+	qDebug() << "Writing account list to file.";
+	QFile file(path);
+
+	// Try to open the file and fail if we can't.
+	// TODO: We should probably report this error to the user.
+	if (!file.open(QIODevice::WriteOnly))
+	{
+		qCritical() << QString("Failed to read the account list file (%1).").arg(path).toUtf8();
+		return false;
+	}
+
+	// Write the JSON to the file.
+	file.write(doc.toJson());
+	file.setPermissions(QFile::ReadOwner|QFile::WriteOwner|QFile::ReadUser|QFile::WriteUser);
+	file.close();
+
+	qDebug() << "Saved account list to" << path;
+
+	return true;
+}
+
+void MojangAccountList::setListFilePath(QString path, bool autosave)
+{
+	m_listFilePath = path;
+	m_autosave = autosave;
+}
+
+bool MojangAccountList::anyAccountIsValid()
+{
+	for(auto account:m_accounts)
+	{
+		if(account->accountStatus() != NotVerified)
+			return true;
+	}
+	return false;
+}
diff --git a/libraries/logic/minecraft/auth/MojangAccountList.h b/libraries/logic/minecraft/auth/MojangAccountList.h
new file mode 100644
index 00000000..c40fa6a3
--- /dev/null
+++ b/libraries/logic/minecraft/auth/MojangAccountList.h
@@ -0,0 +1,201 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "MojangAccount.h"
+
+#include <QObject>
+#include <QVariant>
+#include <QAbstractListModel>
+#include <QSharedPointer>
+
+#include "multimc_logic_export.h"
+
+/*!
+ * \brief List of available Mojang accounts.
+ * This should be loaded in the background by MultiMC on startup.
+ *
+ * This class also inherits from QAbstractListModel. Methods from that
+ * class determine how this list shows up in a list view. Said methods
+ * all have a default implementation, but they can be overridden by subclasses to
+ * change the behavior of the list.
+ */
+class MULTIMC_LOGIC_EXPORT MojangAccountList : public QAbstractListModel
+{
+	Q_OBJECT
+public:
+	enum ModelRoles
+	{
+		PointerRole = 0x34B1CB48
+	};
+
+	enum VListColumns
+	{
+		// TODO: Add icon column.
+
+		// First column - Active?
+		ActiveColumn = 0,
+
+		// Second column - Name
+		NameColumn,
+	};
+
+	explicit MojangAccountList(QObject *parent = 0);
+
+	//! Gets the account at the given index.
+	virtual const MojangAccountPtr at(int i) const;
+
+	//! Returns the number of accounts in the list.
+	virtual int count() const;
+
+	//////// List Model Functions ////////
+	virtual QVariant data(const QModelIndex &index, int role) const;
+	virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const;
+	virtual int rowCount(const QModelIndex &parent) const;
+	virtual int columnCount(const QModelIndex &parent) const;
+	virtual Qt::ItemFlags flags(const QModelIndex &index) const;
+	virtual bool setData(const QModelIndex &index, const QVariant &value, int role);
+
+	/*!
+	 * Adds a the given Mojang account to the account list.
+	 */
+	virtual void addAccount(const MojangAccountPtr account);
+
+	/*!
+	 * Removes the mojang account with the given username from the account list.
+	 */
+	virtual void removeAccount(const QString &username);
+
+	/*!
+	 * Removes the account at the given QModelIndex.
+	 */
+	virtual void removeAccount(QModelIndex index);
+
+	/*!
+	 * \brief Finds an account by its username.
+	 * \param The username of the account to find.
+	 * \return A const pointer to the account with the given username. NULL if
+	 * one doesn't exist.
+	 */
+	virtual MojangAccountPtr findAccount(const QString &username) const;
+
+	/*!
+	 * Sets the default path to save the list file to.
+	 * If autosave is true, this list will automatically save to the given path whenever it changes.
+	 * THIS FUNCTION DOES NOT LOAD THE LIST. If you set autosave, be sure to call loadList() immediately
+	 * after calling this function to ensure an autosaved change doesn't overwrite the list you intended
+	 * to load.
+	 */
+	virtual void setListFilePath(QString path, bool autosave = false);
+
+	/*!
+	 * \brief Loads the account list from the given file path.
+	 * If the given file is an empty string (default), will load from the default account list file.
+	 * \return True if successful, otherwise false.
+	 */
+	virtual bool loadList(const QString &file = "");
+
+	/*!
+	 * \brief Saves the account list to the given file.
+	 * If the given file is an empty string (default), will save from the default account list file.
+	 * \return True if successful, otherwise false.
+	 */
+	virtual bool saveList(const QString &file = "");
+
+	/*!
+	 * \brief Gets a pointer to the account that the user has selected as their "active" account.
+	 * Which account is active can be overridden on a per-instance basis, but this will return the one that
+	 * is set as active globally.
+	 * \return The currently active MojangAccount. If there isn't an active account, returns a null pointer.
+	 */
+	virtual MojangAccountPtr activeAccount() const;
+
+	/*!
+	 * Sets the given account as the current active account.
+	 * If the username given is an empty string, sets the active account to nothing.
+	 */
+	virtual void setActiveAccount(const QString &username);
+
+	/*!
+	 * Returns true if any of the account is at least Validated
+	 */
+	bool anyAccountIsValid();
+
+signals:
+	/*!
+	 * Signal emitted to indicate that the account list has changed.
+	 * This will also fire if the value of an element in the list changes (will be implemented
+	 * later).
+	 */
+	void listChanged();
+
+	/*!
+	 * Signal emitted to indicate that the active account has changed.
+	 */
+	void activeAccountChanged();
+
+public
+slots:
+	/**
+	 * This is called when one of the accounts changes and the list needs to be updated
+	 */
+	void accountChanged();
+
+protected:
+	/*!
+	 * Called whenever the list changes.
+	 * This emits the listChanged() signal and autosaves the list (if autosave is enabled).
+	 */
+	void onListChanged();
+
+	/*!
+	 * Called whenever the active account changes.
+	 * Emits the activeAccountChanged() signal and autosaves the list if enabled.
+	 */
+	void onActiveChanged();
+
+	QList<MojangAccountPtr> m_accounts;
+
+	/*!
+	 * Account that is currently active.
+	 */
+	MojangAccountPtr m_activeAccount;
+
+	//! Path to the account list file. Empty string if there isn't one.
+	QString m_listFilePath;
+
+	/*!
+	 * If true, the account list will automatically save to the account list path when it changes.
+	 * Ignored if m_listFilePath is blank.
+	 */
+	bool m_autosave = false;
+
+protected
+slots:
+	/*!
+	 * Updates this list with the given list of accounts.
+	 * This is done by copying each account in the given list and inserting it
+	 * into this one.
+	 * We need to do this so that we can set the parents of the accounts are set to this
+	 * account list. This can't be done in the load task, because the accounts the load
+	 * task creates are on the load task's thread and Qt won't allow their parents
+	 * to be set to something created on another thread.
+	 * To get around that problem, we invoke this method on the GUI thread, which
+	 * then copies the accounts and sets their parents correctly.
+	 * \param accounts List of accounts whose parents should be set.
+	 */
+	virtual void updateListData(QList<MojangAccountPtr> versions);
+};
diff --git a/libraries/logic/minecraft/auth/YggdrasilTask.cpp b/libraries/logic/minecraft/auth/YggdrasilTask.cpp
new file mode 100644
index 00000000..c6971c9f
--- /dev/null
+++ b/libraries/logic/minecraft/auth/YggdrasilTask.cpp
@@ -0,0 +1,255 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "YggdrasilTask.h"
+#include "MojangAccount.h"
+
+#include <QObject>
+#include <QString>
+#include <QJsonObject>
+#include <QJsonDocument>
+#include <QNetworkReply>
+#include <QByteArray>
+
+#include <Env.h>
+
+#include <net/URLConstants.h>
+
+#include <QDebug>
+
+YggdrasilTask::YggdrasilTask(MojangAccount *account, QObject *parent)
+	: Task(parent), m_account(account)
+{
+	changeState(STATE_CREATED);
+}
+
+void YggdrasilTask::executeTask()
+{
+	changeState(STATE_SENDING_REQUEST);
+
+	// Get the content of the request we're going to send to the server.
+	QJsonDocument doc(getRequestContent());
+
+	auto worker = ENV.qnam();
+	QUrl reqUrl("https://" + URLConstants::AUTH_BASE + getEndpoint());
+	QNetworkRequest netRequest(reqUrl);
+	netRequest.setHeader(QNetworkRequest::ContentTypeHeader, "application/json");
+
+	QByteArray requestData = doc.toJson();
+	m_netReply = worker->post(netRequest, requestData);
+	connect(m_netReply, &QNetworkReply::finished, this, &YggdrasilTask::processReply);
+	connect(m_netReply, &QNetworkReply::uploadProgress, this, &YggdrasilTask::refreshTimers);
+	connect(m_netReply, &QNetworkReply::downloadProgress, this, &YggdrasilTask::refreshTimers);
+	connect(m_netReply, &QNetworkReply::sslErrors, this, &YggdrasilTask::sslErrors);
+	timeout_keeper.setSingleShot(true);
+	timeout_keeper.start(timeout_max);
+	counter.setSingleShot(false);
+	counter.start(time_step);
+	progress(0, timeout_max);
+	connect(&timeout_keeper, &QTimer::timeout, this, &YggdrasilTask::abortByTimeout);
+	connect(&counter, &QTimer::timeout, this, &YggdrasilTask::heartbeat);
+}
+
+void YggdrasilTask::refreshTimers(qint64, qint64)
+{
+	timeout_keeper.stop();
+	timeout_keeper.start(timeout_max);
+	progress(count = 0, timeout_max);
+}
+void YggdrasilTask::heartbeat()
+{
+	count += time_step;
+	progress(count, timeout_max);
+}
+
+bool YggdrasilTask::abort()
+{
+	progress(timeout_max, timeout_max);
+	// TODO: actually use this in a meaningful way
+	m_aborted = YggdrasilTask::BY_USER;
+	m_netReply->abort();
+	return true;
+}
+
+void YggdrasilTask::abortByTimeout()
+{
+	progress(timeout_max, timeout_max);
+	// TODO: actually use this in a meaningful way
+	m_aborted = YggdrasilTask::BY_TIMEOUT;
+	m_netReply->abort();
+}
+
+void YggdrasilTask::sslErrors(QList<QSslError> errors)
+{
+	int i = 1;
+	for (auto error : errors)
+	{
+		qCritical() << "LOGIN SSL Error #" << i << " : " << error.errorString();
+		auto cert = error.certificate();
+		qCritical() << "Certificate in question:\n" << cert.toText();
+		i++;
+	}
+}
+
+void YggdrasilTask::processReply()
+{
+	changeState(STATE_PROCESSING_RESPONSE);
+
+	switch (m_netReply->error())
+	{
+	case QNetworkReply::NoError:
+		break;
+	case QNetworkReply::TimeoutError:
+		changeState(STATE_FAILED_SOFT, tr("Authentication operation timed out."));
+		return;
+	case QNetworkReply::OperationCanceledError:
+		changeState(STATE_FAILED_SOFT, tr("Authentication operation cancelled."));
+		return;
+	case QNetworkReply::SslHandshakeFailedError:
+		changeState(
+			STATE_FAILED_SOFT,
+			tr("<b>SSL Handshake failed.</b><br/>There might be a few causes for it:<br/>"
+			   "<ul>"
+			   "<li>You use Windows XP and need to <a "
+			   "href=\"http://www.microsoft.com/en-us/download/details.aspx?id=38918\">update "
+			   "your root certificates</a></li>"
+			   "<li>Some device on your network is interfering with SSL traffic. In that case, "
+			   "you have bigger worries than Minecraft not starting.</li>"
+			   "<li>Possibly something else. Check the MultiMC log file for details</li>"
+			   "</ul>"));
+		return;
+	// used for invalid credentials and similar errors. Fall through.
+	case QNetworkReply::ContentOperationNotPermittedError:
+		break;
+	default:
+		changeState(STATE_FAILED_SOFT,
+					tr("Authentication operation failed due to a network error: %1 (%2)")
+						.arg(m_netReply->errorString()).arg(m_netReply->error()));
+		return;
+	}
+
+	// Try to parse the response regardless of the response code.
+	// Sometimes the auth server will give more information and an error code.
+	QJsonParseError jsonError;
+	QByteArray replyData = m_netReply->readAll();
+	QJsonDocument doc = QJsonDocument::fromJson(replyData, &jsonError);
+	// Check the response code.
+	int responseCode = m_netReply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
+
+	if (responseCode == 200)
+	{
+		// If the response code was 200, then there shouldn't be an error. Make sure
+		// anyways.
+		// Also, sometimes an empty reply indicates success. If there was no data received,
+		// pass an empty json object to the processResponse function.
+		if (jsonError.error == QJsonParseError::NoError || replyData.size() == 0)
+		{
+			processResponse(replyData.size() > 0 ? doc.object() : QJsonObject());
+			return;
+		}
+		else
+		{
+			changeState(STATE_FAILED_SOFT, tr("Failed to parse authentication server response "
+											  "JSON response: %1 at offset %2.")
+											   .arg(jsonError.errorString())
+											   .arg(jsonError.offset));
+			qCritical() << replyData;
+		}
+		return;
+	}
+
+	// If the response code was not 200, then Yggdrasil may have given us information
+	// about the error.
+	// If we can parse the response, then get information from it. Otherwise just say
+	// there was an unknown error.
+	if (jsonError.error == QJsonParseError::NoError)
+	{
+		// We were able to parse the server's response. Woo!
+		// Call processError. If a subclass has overridden it then they'll handle their
+		// stuff there.
+		qDebug() << "The request failed, but the server gave us an error message. "
+						"Processing error.";
+		processError(doc.object());
+	}
+	else
+	{
+		// The server didn't say anything regarding the error. Give the user an unknown
+		// error.
+		qDebug()
+			<< "The request failed and the server gave no error message. Unknown error.";
+		changeState(STATE_FAILED_SOFT,
+					tr("An unknown error occurred when trying to communicate with the "
+					   "authentication server: %1").arg(m_netReply->errorString()));
+	}
+}
+
+void YggdrasilTask::processError(QJsonObject responseData)
+{
+	QJsonValue errorVal = responseData.value("error");
+	QJsonValue errorMessageValue = responseData.value("errorMessage");
+	QJsonValue causeVal = responseData.value("cause");
+
+	if (errorVal.isString() && errorMessageValue.isString())
+	{
+		m_error = std::shared_ptr<Error>(new Error{
+			errorVal.toString(""), errorMessageValue.toString(""), causeVal.toString("")});
+		changeState(STATE_FAILED_HARD, m_error->m_errorMessageVerbose);
+	}
+	else
+	{
+		// Error is not in standard format. Don't set m_error and return unknown error.
+		changeState(STATE_FAILED_HARD, tr("An unknown Yggdrasil error occurred."));
+	}
+}
+
+QString YggdrasilTask::getStateMessage() const
+{
+	switch (m_state)
+	{
+	case STATE_CREATED:
+		return "Waiting...";
+	case STATE_SENDING_REQUEST:
+		return tr("Sending request to auth servers...");
+	case STATE_PROCESSING_RESPONSE:
+		return tr("Processing response from servers...");
+	case STATE_SUCCEEDED:
+		return tr("Authentication task succeeded.");
+	case STATE_FAILED_SOFT:
+		return tr("Failed to contact the authentication server.");
+	case STATE_FAILED_HARD:
+		return tr("Failed to authenticate.");
+	default:
+		return tr("...");
+	}
+}
+
+void YggdrasilTask::changeState(YggdrasilTask::State newState, QString reason)
+{
+	m_state = newState;
+	setStatus(getStateMessage());
+	if (newState == STATE_SUCCEEDED)
+	{
+		emitSucceeded();
+	}
+	else if (newState == STATE_FAILED_HARD || newState == STATE_FAILED_SOFT)
+	{
+		emitFailed(reason);
+	}
+}
+
+YggdrasilTask::State YggdrasilTask::state()
+{
+	return m_state;
+}
diff --git a/libraries/logic/minecraft/auth/YggdrasilTask.h b/libraries/logic/minecraft/auth/YggdrasilTask.h
new file mode 100644
index 00000000..c84cfc06
--- /dev/null
+++ b/libraries/logic/minecraft/auth/YggdrasilTask.h
@@ -0,0 +1,150 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <tasks/Task.h>
+
+#include <QString>
+#include <QJsonObject>
+#include <QTimer>
+#include <qsslerror.h>
+
+#include "MojangAccount.h"
+
+class QNetworkReply;
+
+/**
+ * A Yggdrasil task is a task that performs an operation on a given mojang account.
+ */
+class YggdrasilTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit YggdrasilTask(MojangAccount * account, QObject *parent = 0);
+
+	/**
+	 * assign a session to this task. the session will be filled with required infomration
+	 * upon completion
+	 */
+	void assignSession(AuthSessionPtr session)
+	{
+		m_session = session;
+	}
+
+	/// get the assigned session for filling with information.
+	AuthSessionPtr getAssignedSession()
+	{
+		return m_session;
+	}
+
+	/**
+	 * Class describing a Yggdrasil error response.
+	 */
+	struct Error
+	{
+		QString m_errorMessageShort;
+		QString m_errorMessageVerbose;
+		QString m_cause;
+	};
+
+	enum AbortedBy
+	{
+		BY_NOTHING,
+		BY_USER,
+		BY_TIMEOUT
+	} m_aborted = BY_NOTHING;
+
+	/**
+	 * Enum for describing the state of the current task.
+	 * Used by the getStateMessage function to determine what the status message should be.
+	 */
+	enum State
+	{
+		STATE_CREATED,
+		STATE_SENDING_REQUEST,
+		STATE_PROCESSING_RESPONSE,
+		STATE_FAILED_SOFT, //!< soft failure. this generally means the user auth details haven't been invalidated
+		STATE_FAILED_HARD, //!< hard failure. auth is invalid
+		STATE_SUCCEEDED
+	} m_state = STATE_CREATED;
+
+protected:
+
+	virtual void executeTask() override;
+
+	/**
+	 * Gets the JSON object that will be sent to the authentication server.
+	 * Should be overridden by subclasses.
+	 */
+	virtual QJsonObject getRequestContent() const = 0;
+
+	/**
+	 * Gets the endpoint to POST to.
+	 * No leading slash.
+	 */
+	virtual QString getEndpoint() const = 0;
+
+	/**
+	 * Processes the response received from the server.
+	 * If an error occurred, this should emit a failed signal and return false.
+	 * If Yggdrasil gave an error response, it should call setError() first, and then return false.
+	 * Otherwise, it should return true.
+	 * Note: If the response from the server was blank, and the HTTP code was 200, this function is called with
+	 * an empty QJsonObject.
+	 */
+	virtual void processResponse(QJsonObject responseData) = 0;
+
+	/**
+	 * Processes an error response received from the server.
+	 * The default implementation will read data from Yggdrasil's standard error response format and set it as this task's Error.
+	 * \returns a QString error message that will be passed to emitFailed.
+	 */
+	virtual void processError(QJsonObject responseData);
+
+	/**
+	 * Returns the state message for the given state.
+	 * Used to set the status message for the task.
+	 * Should be overridden by subclasses that want to change messages for a given state.
+	 */
+	virtual QString getStateMessage() const;
+
+protected
+slots:
+	void processReply();
+	void refreshTimers(qint64, qint64);
+	void heartbeat();
+	void sslErrors(QList<QSslError>);
+
+	void changeState(State newState, QString reason=QString());
+public
+slots:
+	virtual bool abort() override;
+	void abortByTimeout();
+	State state();
+protected:
+	// FIXME: segfault disaster waiting to happen
+	MojangAccount *m_account = nullptr;
+	QNetworkReply *m_netReply = nullptr;
+	std::shared_ptr<Error> m_error;
+	QTimer timeout_keeper;
+	QTimer counter;
+	int count = 0; // num msec since time reset
+
+	const int timeout_max = 30000;
+	const int time_step = 50;
+
+	AuthSessionPtr m_session;
+};
diff --git a/libraries/logic/minecraft/auth/flows/AuthenticateTask.cpp b/libraries/logic/minecraft/auth/flows/AuthenticateTask.cpp
new file mode 100644
index 00000000..8d136f0b
--- /dev/null
+++ b/libraries/logic/minecraft/auth/flows/AuthenticateTask.cpp
@@ -0,0 +1,202 @@
+
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "AuthenticateTask.h"
+#include "../MojangAccount.h"
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QVariant>
+
+#include <QDebug>
+#include <QUuid>
+
+AuthenticateTask::AuthenticateTask(MojangAccount * account, const QString &password,
+								   QObject *parent)
+	: YggdrasilTask(account, parent), m_password(password)
+{
+}
+
+QJsonObject AuthenticateTask::getRequestContent() const
+{
+	/*
+	 * {
+	 *   "agent": {								// optional
+	 *   "name": "Minecraft",					// So far this is the only encountered value
+	 *   "version": 1							// This number might be increased
+	 * 											// by the vanilla client in the future
+	 *   },
+	 *   "username": "mojang account name",		// Can be an email address or player name for
+												// unmigrated accounts
+	 *  "password": "mojang account password",
+	 *  "clientToken": "client identifier"		// optional
+	 *  "requestUser": true/false               // request the user structure
+	 * }
+	 */
+	QJsonObject req;
+
+	{
+		QJsonObject agent;
+		// C++ makes string literals void* for some stupid reason, so we have to tell it
+		// QString... Thanks Obama.
+		agent.insert("name", QString("Minecraft"));
+		agent.insert("version", 1);
+		req.insert("agent", agent);
+	}
+
+	req.insert("username", m_account->username());
+	req.insert("password", m_password);
+	req.insert("requestUser", true);
+
+	// If we already have a client token, give it to the server.
+	// Otherwise, let the server give us one.
+
+	if(m_account->m_clientToken.isEmpty())
+	{
+		auto uuid = QUuid::createUuid();
+		auto uuidString = uuid.toString().remove('{').remove('-').remove('}');
+		m_account->m_clientToken = uuidString;
+	}
+	req.insert("clientToken", m_account->m_clientToken);
+
+	return req;
+}
+
+void AuthenticateTask::processResponse(QJsonObject responseData)
+{
+	// Read the response data. We need to get the client token, access token, and the selected
+	// profile.
+	qDebug() << "Processing authentication response.";
+	// qDebug() << responseData;
+	// If we already have a client token, make sure the one the server gave us matches our
+	// existing one.
+	qDebug() << "Getting client token.";
+	QString clientToken = responseData.value("clientToken").toString("");
+	if (clientToken.isEmpty())
+	{
+		// Fail if the server gave us an empty client token
+		changeState(STATE_FAILED_HARD, tr("Authentication server didn't send a client token."));
+		return;
+	}
+	if (!m_account->m_clientToken.isEmpty() && clientToken != m_account->m_clientToken)
+	{
+		changeState(STATE_FAILED_HARD, tr("Authentication server attempted to change the client token. This isn't supported."));
+		return;
+	}
+	// Set the client token.
+	m_account->m_clientToken = clientToken;
+
+	// Now, we set the access token.
+	qDebug() << "Getting access token.";
+	QString accessToken = responseData.value("accessToken").toString("");
+	if (accessToken.isEmpty())
+	{
+		// Fail if the server didn't give us an access token.
+		changeState(STATE_FAILED_HARD, tr("Authentication server didn't send an access token."));
+		return;
+	}
+	// Set the access token.
+	m_account->m_accessToken = accessToken;
+
+	// Now we load the list of available profiles.
+	// Mojang hasn't yet implemented the profile system,
+	// but we might as well support what's there so we
+	// don't have trouble implementing it later.
+	qDebug() << "Loading profile list.";
+	QJsonArray availableProfiles = responseData.value("availableProfiles").toArray();
+	QList<AccountProfile> loadedProfiles;
+	for (auto iter : availableProfiles)
+	{
+		QJsonObject profile = iter.toObject();
+		// Profiles are easy, we just need their ID and name.
+		QString id = profile.value("id").toString("");
+		QString name = profile.value("name").toString("");
+		bool legacy = profile.value("legacy").toBool(false);
+
+		if (id.isEmpty() || name.isEmpty())
+		{
+			// This should never happen, but we might as well
+			// warn about it if it does so we can debug it easily.
+			// You never know when Mojang might do something truly derpy.
+			qWarning() << "Found entry in available profiles list with missing ID or name "
+						   "field. Ignoring it.";
+		}
+
+		// Now, add a new AccountProfile entry to the list.
+		loadedProfiles.append({id, name, legacy});
+	}
+	// Put the list of profiles we loaded into the MojangAccount object.
+	m_account->m_profiles = loadedProfiles;
+
+	// Finally, we set the current profile to the correct value. This is pretty simple.
+	// We do need to make sure that the current profile that the server gave us
+	// is actually in the available profiles list.
+	// If it isn't, we'll just fail horribly (*shouldn't* ever happen, but you never know).
+	qDebug() << "Setting current profile.";
+	QJsonObject currentProfile = responseData.value("selectedProfile").toObject();
+	QString currentProfileId = currentProfile.value("id").toString("");
+	if (currentProfileId.isEmpty())
+	{
+		changeState(STATE_FAILED_HARD, tr("Authentication server didn't specify a currently selected profile. The account exists, but likely isn't premium."));
+		return;
+	}
+	if (!m_account->setCurrentProfile(currentProfileId))
+	{
+		changeState(STATE_FAILED_HARD, tr("Authentication server specified a selected profile that wasn't in the available profiles list."));
+		return;
+	}
+
+	// this is what the vanilla launcher passes to the userProperties launch param
+	if (responseData.contains("user"))
+	{
+		User u;
+		auto obj = responseData.value("user").toObject();
+		u.id = obj.value("id").toString();
+		auto propArray = obj.value("properties").toArray();
+		for (auto prop : propArray)
+		{
+			auto propTuple = prop.toObject();
+			auto name = propTuple.value("name").toString();
+			auto value = propTuple.value("value").toString();
+			u.properties.insert(name, value);
+		}
+		m_account->m_user = u;
+	}
+
+	// We've made it through the minefield of possible errors. Return true to indicate that
+	// we've succeeded.
+	qDebug() << "Finished reading authentication response.";
+	changeState(STATE_SUCCEEDED);
+}
+
+QString AuthenticateTask::getEndpoint() const
+{
+	return "authenticate";
+}
+
+QString AuthenticateTask::getStateMessage() const
+{
+	switch (m_state)
+	{
+	case STATE_SENDING_REQUEST:
+		return tr("Authenticating: Sending request...");
+	case STATE_PROCESSING_RESPONSE:
+		return tr("Authenticating: Processing response...");
+	default:
+		return YggdrasilTask::getStateMessage();
+	}
+}
diff --git a/libraries/logic/minecraft/auth/flows/AuthenticateTask.h b/libraries/logic/minecraft/auth/flows/AuthenticateTask.h
new file mode 100644
index 00000000..398fab98
--- /dev/null
+++ b/libraries/logic/minecraft/auth/flows/AuthenticateTask.h
@@ -0,0 +1,46 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "../YggdrasilTask.h"
+
+#include <QObject>
+#include <QString>
+#include <QJsonObject>
+
+/**
+ * The authenticate task takes a MojangAccount with no access token and password and attempts to
+ * authenticate with Mojang's servers.
+ * If successful, it will set the MojangAccount's access token.
+ */
+class AuthenticateTask : public YggdrasilTask
+{
+	Q_OBJECT
+public:
+	AuthenticateTask(MojangAccount *account, const QString &password, QObject *parent = 0);
+
+protected:
+	virtual QJsonObject getRequestContent() const override;
+
+	virtual QString getEndpoint() const override;
+
+	virtual void processResponse(QJsonObject responseData) override;
+
+	virtual QString getStateMessage() const override;
+
+private:
+	QString m_password;
+};
diff --git a/libraries/logic/minecraft/auth/flows/RefreshTask.cpp b/libraries/logic/minecraft/auth/flows/RefreshTask.cpp
new file mode 100644
index 00000000..a0fb2e48
--- /dev/null
+++ b/libraries/logic/minecraft/auth/flows/RefreshTask.cpp
@@ -0,0 +1,144 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "RefreshTask.h"
+#include "../MojangAccount.h"
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QVariant>
+
+#include <QDebug>
+
+RefreshTask::RefreshTask(MojangAccount *account) : YggdrasilTask(account)
+{
+}
+
+QJsonObject RefreshTask::getRequestContent() const
+{
+	/*
+	 * {
+	 *  "clientToken": "client identifier"
+	 *  "accessToken": "current access token to be refreshed"
+	 *  "selectedProfile":                      // specifying this causes errors
+	 *  {
+	 *   "id": "profile ID"
+	 *   "name": "profile name"
+	 *  }
+	 *  "requestUser": true/false               // request the user structure
+	 * }
+	 */
+	QJsonObject req;
+	req.insert("clientToken", m_account->m_clientToken);
+	req.insert("accessToken", m_account->m_accessToken);
+	/*
+	{
+		auto currentProfile = m_account->currentProfile();
+		QJsonObject profile;
+		profile.insert("id", currentProfile->id());
+		profile.insert("name", currentProfile->name());
+		req.insert("selectedProfile", profile);
+	}
+	*/
+	req.insert("requestUser", true);
+
+	return req;
+}
+
+void RefreshTask::processResponse(QJsonObject responseData)
+{
+	// Read the response data. We need to get the client token, access token, and the selected
+	// profile.
+	qDebug() << "Processing authentication response.";
+
+	// qDebug() << responseData;
+	// If we already have a client token, make sure the one the server gave us matches our
+	// existing one.
+	QString clientToken = responseData.value("clientToken").toString("");
+	if (clientToken.isEmpty())
+	{
+		// Fail if the server gave us an empty client token
+		changeState(STATE_FAILED_HARD, tr("Authentication server didn't send a client token."));
+		return;
+	}
+	if (!m_account->m_clientToken.isEmpty() && clientToken != m_account->m_clientToken)
+	{
+		changeState(STATE_FAILED_HARD, tr("Authentication server attempted to change the client token. This isn't supported."));
+		return;
+	}
+
+	// Now, we set the access token.
+	qDebug() << "Getting new access token.";
+	QString accessToken = responseData.value("accessToken").toString("");
+	if (accessToken.isEmpty())
+	{
+		// Fail if the server didn't give us an access token.
+		changeState(STATE_FAILED_HARD, tr("Authentication server didn't send an access token."));
+		return;
+	}
+
+	// we validate that the server responded right. (our current profile = returned current
+	// profile)
+	QJsonObject currentProfile = responseData.value("selectedProfile").toObject();
+	QString currentProfileId = currentProfile.value("id").toString("");
+	if (m_account->currentProfile()->id != currentProfileId)
+	{
+		changeState(STATE_FAILED_HARD, tr("Authentication server didn't specify the same prefile as expected."));
+		return;
+	}
+
+	// this is what the vanilla launcher passes to the userProperties launch param
+	if (responseData.contains("user"))
+	{
+		User u;
+		auto obj = responseData.value("user").toObject();
+		u.id = obj.value("id").toString();
+		auto propArray = obj.value("properties").toArray();
+		for (auto prop : propArray)
+		{
+			auto propTuple = prop.toObject();
+			auto name = propTuple.value("name").toString();
+			auto value = propTuple.value("value").toString();
+			u.properties.insert(name, value);
+		}
+		m_account->m_user = u;
+	}
+
+	// We've made it through the minefield of possible errors. Return true to indicate that
+	// we've succeeded.
+	qDebug() << "Finished reading refresh response.";
+	// Reset the access token.
+	m_account->m_accessToken = accessToken;
+	changeState(STATE_SUCCEEDED);
+}
+
+QString RefreshTask::getEndpoint() const
+{
+	return "refresh";
+}
+
+QString RefreshTask::getStateMessage() const
+{
+	switch (m_state)
+	{
+	case STATE_SENDING_REQUEST:
+		return tr("Refreshing login token...");
+	case STATE_PROCESSING_RESPONSE:
+		return tr("Refreshing login token: Processing response...");
+	default:
+		return YggdrasilTask::getStateMessage();
+	}
+}
diff --git a/libraries/logic/minecraft/auth/flows/RefreshTask.h b/libraries/logic/minecraft/auth/flows/RefreshTask.h
new file mode 100644
index 00000000..17714b4f
--- /dev/null
+++ b/libraries/logic/minecraft/auth/flows/RefreshTask.h
@@ -0,0 +1,44 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "../YggdrasilTask.h"
+
+#include <QObject>
+#include <QString>
+#include <QJsonObject>
+
+/**
+ * The authenticate task takes a MojangAccount with a possibly timed-out access token
+ * and attempts to authenticate with Mojang's servers.
+ * If successful, it will set the new access token. The token is considered validated.
+ */
+class RefreshTask : public YggdrasilTask
+{
+	Q_OBJECT
+public:
+	RefreshTask(MojangAccount * account);
+
+protected:
+	virtual QJsonObject getRequestContent() const override;
+
+	virtual QString getEndpoint() const override;
+
+	virtual void processResponse(QJsonObject responseData) override;
+
+	virtual QString getStateMessage() const override;
+};
+
diff --git a/libraries/logic/minecraft/auth/flows/ValidateTask.cpp b/libraries/logic/minecraft/auth/flows/ValidateTask.cpp
new file mode 100644
index 00000000..4deceb6a
--- /dev/null
+++ b/libraries/logic/minecraft/auth/flows/ValidateTask.cpp
@@ -0,0 +1,61 @@
+
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ValidateTask.h"
+#include "../MojangAccount.h"
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QVariant>
+
+#include <QDebug>
+
+ValidateTask::ValidateTask(MojangAccount * account, QObject *parent)
+	: YggdrasilTask(account, parent)
+{
+}
+
+QJsonObject ValidateTask::getRequestContent() const
+{
+	QJsonObject req;
+	req.insert("accessToken", m_account->m_accessToken);
+	return req;
+}
+
+void ValidateTask::processResponse(QJsonObject responseData)
+{
+	// Assume that if processError wasn't called, then the request was successful.
+	changeState(YggdrasilTask::STATE_SUCCEEDED);
+}
+
+QString ValidateTask::getEndpoint() const
+{
+	return "validate";
+}
+
+QString ValidateTask::getStateMessage() const
+{
+	switch (m_state)
+	{
+	case YggdrasilTask::STATE_SENDING_REQUEST:
+		return tr("Validating access token: Sending request...");
+	case YggdrasilTask::STATE_PROCESSING_RESPONSE:
+		return tr("Validating access token: Processing response...");
+	default:
+		return YggdrasilTask::getStateMessage();
+	}
+}
diff --git a/libraries/logic/minecraft/auth/flows/ValidateTask.h b/libraries/logic/minecraft/auth/flows/ValidateTask.h
new file mode 100644
index 00000000..77d628a0
--- /dev/null
+++ b/libraries/logic/minecraft/auth/flows/ValidateTask.h
@@ -0,0 +1,47 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * :FIXME: DEAD CODE, DEAD CODE, DEAD CODE! :FIXME:
+ */
+
+#pragma once
+
+#include "../YggdrasilTask.h"
+
+#include <QObject>
+#include <QString>
+#include <QJsonObject>
+
+/**
+ * The validate task takes a MojangAccount and checks to make sure its access token is valid.
+ */
+class ValidateTask : public YggdrasilTask
+{
+	Q_OBJECT
+public:
+	ValidateTask(MojangAccount *account, QObject *parent = 0);
+
+protected:
+	virtual QJsonObject getRequestContent() const override;
+
+	virtual QString getEndpoint() const override;
+
+	virtual void processResponse(QJsonObject responseData) override;
+
+	virtual QString getStateMessage() const override;
+
+private:
+};
diff --git a/libraries/logic/minecraft/forge/ForgeInstaller.cpp b/libraries/logic/minecraft/forge/ForgeInstaller.cpp
new file mode 100644
index 00000000..353328ab
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeInstaller.cpp
@@ -0,0 +1,458 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ForgeInstaller.h"
+#include "ForgeVersionList.h"
+
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/GradleSpecifier.h"
+#include "net/HttpMetaCache.h"
+#include "tasks/Task.h"
+#include "minecraft/onesix/OneSixInstance.h"
+#include <minecraft/onesix/OneSixVersionFormat.h>
+#include "minecraft/VersionFilterData.h"
+#include "minecraft/MinecraftVersion.h"
+#include "Env.h"
+#include "Exception.h"
+#include <FileSystem.h>
+
+#include <quazip.h>
+#include <quazipfile.h>
+#include <QStringList>
+#include <QRegularExpression>
+#include <QRegularExpressionMatch>
+
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QSaveFile>
+#include <QCryptographicHash>
+
+ForgeInstaller::ForgeInstaller() : BaseInstaller()
+{
+}
+
+void ForgeInstaller::prepare(const QString &filename, const QString &universalUrl)
+{
+	VersionFilePtr newVersion;
+	m_universal_url = universalUrl;
+
+	QuaZip zip(filename);
+	if (!zip.open(QuaZip::mdUnzip))
+		return;
+
+	QuaZipFile file(&zip);
+
+	// read the install profile
+	if (!zip.setCurrentFile("install_profile.json"))
+		return;
+
+	QJsonParseError jsonError;
+	if (!file.open(QIODevice::ReadOnly))
+		return;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(file.readAll(), &jsonError);
+	file.close();
+	if (jsonError.error != QJsonParseError::NoError)
+		return;
+
+	if (!jsonDoc.isObject())
+		return;
+
+	QJsonObject root = jsonDoc.object();
+
+	auto installVal = root.value("install");
+	auto versionInfoVal = root.value("versionInfo");
+	if (!installVal.isObject() || !versionInfoVal.isObject())
+		return;
+
+	try
+	{
+		newVersion = OneSixVersionFormat::versionFileFromJson(QJsonDocument(versionInfoVal.toObject()), QString(), false);
+	}
+	catch(Exception &err)
+	{
+		qWarning() << "Forge: Fatal error while parsing version file:" << err.what();
+		return;
+	}
+
+	for(auto problem: newVersion->getProblems())
+	{
+		qWarning() << "Forge: Problem found: " << problem.getDescription();
+	}
+	if(newVersion->getProblemSeverity() == ProblemSeverity::PROBLEM_ERROR)
+	{
+		qWarning() << "Forge: Errors found while parsing version file";
+		return;
+	}
+
+	QJsonObject installObj = installVal.toObject();
+	QString libraryName = installObj.value("path").toString();
+	internalPath = installObj.value("filePath").toString();
+	m_forgeVersionString = installObj.value("version").toString().remove("Forge", Qt::CaseInsensitive).trimmed();
+
+	// where do we put the library? decode the mojang path
+	GradleSpecifier lib(libraryName);
+
+	auto cacheentry = ENV.metacache()->resolveEntry("libraries", lib.toPath());
+	finalPath = "libraries/" + lib.toPath();
+	if (!FS::ensureFilePathExists(finalPath))
+		return;
+
+	if (!zip.setCurrentFile(internalPath))
+		return;
+	if (!file.open(QIODevice::ReadOnly))
+		return;
+	{
+		QByteArray data = file.readAll();
+		// extract file
+		QSaveFile extraction(finalPath);
+		if (!extraction.open(QIODevice::WriteOnly))
+			return;
+		if (extraction.write(data) != data.size())
+			return;
+		if (!extraction.commit())
+			return;
+		QCryptographicHash md5sum(QCryptographicHash::Md5);
+		md5sum.addData(data);
+
+		cacheentry->setStale(false);
+		cacheentry->setMD5Sum(md5sum.result().toHex().constData());
+		ENV.metacache()->updateEntry(cacheentry);
+	}
+	file.close();
+
+	m_forge_json = newVersion;
+}
+
+bool ForgeInstaller::add(OneSixInstance *to)
+{
+	if (!BaseInstaller::add(to))
+	{
+		return false;
+	}
+
+	if (!m_forge_json)
+	{
+		return false;
+	}
+
+	// A blacklist
+	QSet<QString> blacklist{"authlib", "realms"};
+	QList<QString> xzlist{"org.scala-lang", "com.typesafe"};
+
+	// get the minecraft version from the instance
+	VersionFilePtr minecraft;
+	auto minecraftPatch = to->getMinecraftProfile()->versionPatch("net.minecraft");
+	if(minecraftPatch)
+	{
+		minecraft = std::dynamic_pointer_cast<VersionFile>(minecraftPatch);
+		if(!minecraft)
+		{
+			auto mcWrap = std::dynamic_pointer_cast<MinecraftVersion>(minecraftPatch);
+			if(mcWrap)
+			{
+				minecraft = mcWrap->getVersionFile();
+			}
+		}
+	}
+
+	// for each library in the version we are adding (except for the blacklisted)
+	QMutableListIterator<LibraryPtr> iter(m_forge_json->libraries);
+	while (iter.hasNext())
+	{
+		auto library = iter.next();
+		QString libName = library->artifactId();
+		QString libVersion = library->version();
+		QString rawName = library->rawName();
+
+		// ignore lwjgl libraries.
+		if (g_VersionFilterData.lwjglWhitelist.contains(library->artifactPrefix()))
+		{
+			iter.remove();
+			continue;
+		}
+		// ignore other blacklisted (realms, authlib)
+		if (blacklist.contains(libName))
+		{
+			iter.remove();
+			continue;
+		}
+		// if minecraft version was found, ignore everything that is already in the minecraft version
+		if(minecraft)
+		{
+			bool found = false;
+			for (auto & lib: minecraft->libraries)
+			{
+				if(library->artifactPrefix() == lib->artifactPrefix() && library->version() == lib->version())
+				{
+					found = true;
+					break;
+				}
+			}
+			if (found)
+				continue;
+		}
+
+		// if this is the actual forge lib, set an absolute url for the download
+		if (m_forge_version->type == ForgeVersion::Gradle)
+		{
+			if (libName == "forge")
+			{
+				library->setClassifier("universal");
+			}
+			else if (libName == "minecraftforge")
+			{
+				QString forgeCoord("net.minecraftforge:forge:%1:universal");
+				// using insane form of the MC version...
+				QString longVersion = m_forge_version->mcver + "-" + m_forge_version->jobbuildver;
+				GradleSpecifier spec(forgeCoord.arg(longVersion));
+				library->setRawName(spec);
+			}
+		}
+		else
+		{
+			if (libName.contains("minecraftforge"))
+			{
+				library->setAbsoluteUrl(m_universal_url);
+			}
+		}
+
+		// mark bad libraries based on the xzlist above
+		for (auto entry : xzlist)
+		{
+			qDebug() << "Testing " << rawName << " : " << entry;
+			if (rawName.startsWith(entry))
+			{
+				library->setHint("forge-pack-xz");
+				break;
+			}
+		}
+	}
+	QString &args = m_forge_json->minecraftArguments;
+	QStringList tweakers;
+	{
+		QRegularExpression expression("--tweakClass ([a-zA-Z0-9\\.]*)");
+		QRegularExpressionMatch match = expression.match(args);
+		while (match.hasMatch())
+		{
+			tweakers.append(match.captured(1));
+			args.remove(match.capturedStart(), match.capturedLength());
+			match = expression.match(args);
+		}
+		if(tweakers.size())
+		{
+			args.operator=(args.trimmed());
+			m_forge_json->addTweakers = tweakers;
+		}
+	}
+	if(minecraft && args == minecraft->minecraftArguments)
+	{
+		args.clear();
+	}
+
+	m_forge_json->name = "Forge";
+	m_forge_json->fileId = id();
+	m_forge_json->version = m_forgeVersionString;
+	m_forge_json->dependsOnMinecraftVersion = to->intendedVersionId();
+	m_forge_json->order = 5;
+
+	// reset some things we do not want to be passed along.
+	m_forge_json->m_releaseTime = QDateTime();
+	m_forge_json->m_updateTime = QDateTime();
+	m_forge_json->minimumLauncherVersion = -1;
+	m_forge_json->type.clear();
+	m_forge_json->minecraftArguments.clear();
+	m_forge_json->minecraftVersion.clear();
+
+	QSaveFile file(filename(to->instanceRoot()));
+	if (!file.open(QFile::WriteOnly))
+	{
+		qCritical() << "Error opening" << file.fileName()
+					 << "for reading:" << file.errorString();
+		return false;
+	}
+	file.write(OneSixVersionFormat::versionFileToJson(m_forge_json, true).toJson());
+	file.commit();
+
+	return true;
+}
+
+bool ForgeInstaller::addLegacy(OneSixInstance *to)
+{
+	if (!BaseInstaller::add(to))
+	{
+		return false;
+	}
+	auto entry = ENV.metacache()->resolveEntry("minecraftforge", m_forge_version->filename());
+	finalPath = FS::PathCombine(to->jarModsDir(), m_forge_version->filename());
+	if (!FS::ensureFilePathExists(finalPath))
+	{
+		return false;
+	}
+	if (!QFile::copy(entry->getFullPath(), finalPath))
+	{
+		return false;
+	}
+	QJsonObject obj;
+	obj.insert("order", 5);
+	{
+		QJsonArray jarmodsPlus;
+		{
+			QJsonObject libObj;
+			libObj.insert("name", m_forge_version->universal_filename);
+			jarmodsPlus.append(libObj);
+		}
+		obj.insert("+jarMods", jarmodsPlus);
+	}
+
+	obj.insert("name", QString("Forge"));
+	obj.insert("fileId", id());
+	obj.insert("version", m_forge_version->jobbuildver);
+	obj.insert("mcVersion", to->intendedVersionId());
+	if (g_VersionFilterData.fmlLibsMapping.contains(m_forge_version->mcver))
+	{
+		QJsonArray traitsPlus;
+		traitsPlus.append(QString("legacyFML"));
+		obj.insert("+traits", traitsPlus);
+	}
+	auto fullversion = to->getMinecraftProfile();
+	fullversion->remove("net.minecraftforge");
+
+	QFile file(filename(to->instanceRoot()));
+	if (!file.open(QFile::WriteOnly))
+	{
+		qCritical() << "Error opening" << file.fileName()
+					 << "for reading:" << file.errorString();
+		return false;
+	}
+	file.write(QJsonDocument(obj).toJson());
+	file.close();
+	return true;
+}
+
+class ForgeInstallTask : public Task
+{
+	Q_OBJECT
+public:
+	ForgeInstallTask(ForgeInstaller *installer, OneSixInstance *instance,
+					 BaseVersionPtr version, QObject *parent = 0)
+		: Task(parent), m_installer(installer), m_instance(instance), m_version(version)
+	{
+	}
+
+protected:
+	void executeTask() override
+	{
+		setStatus(tr("Installing Forge..."));
+		ForgeVersionPtr forgeVersion = std::dynamic_pointer_cast<ForgeVersion>(m_version);
+		if (!forgeVersion)
+		{
+			emitFailed(tr("Unknown error occured"));
+			return;
+		}
+		prepare(forgeVersion);
+	}
+	void prepare(ForgeVersionPtr forgeVersion)
+	{
+		auto entry = ENV.metacache()->resolveEntry("minecraftforge", forgeVersion->filename());
+		auto installFunction = [this, entry, forgeVersion]()
+		{
+			if (!install(entry, forgeVersion))
+			{
+				qCritical() << "Failure installing Forge";
+				emitFailed(tr("Failure to install Forge"));
+			}
+			else
+			{
+				reload();
+			}
+		};
+
+		/*
+		 * HACK IF the local non-stale file is too small, mark is as stale
+		 *
+		 * This fixes some problems with bad files acquired because of unhandled HTTP redirects
+		 * in old versions of MultiMC.
+		 */
+		if (!entry->isStale())
+		{
+			QFileInfo localFile(entry->getFullPath());
+			if (localFile.size() <= 0x4000)
+			{
+				entry->setStale(true);
+			}
+		}
+
+		if (entry->isStale())
+		{
+			NetJob *fjob = new NetJob("Forge download");
+			fjob->addNetAction(CacheDownload::make(forgeVersion->url(), entry));
+			connect(fjob, &NetJob::progress, this, &Task::setProgress);
+			connect(fjob, &NetJob::status, this, &Task::setStatus);
+			connect(fjob, &NetJob::failed, [this](QString reason)
+			{ emitFailed(tr("Failure to download Forge:\n%1").arg(reason)); });
+			connect(fjob, &NetJob::succeeded, installFunction);
+			fjob->start();
+		}
+		else
+		{
+			installFunction();
+		}
+	}
+	bool install(const std::shared_ptr<MetaEntry> &entry, const ForgeVersionPtr &forgeVersion)
+	{
+		if (forgeVersion->usesInstaller())
+		{
+			QString forgePath = entry->getFullPath();
+			m_installer->prepare(forgePath, forgeVersion->universal_url);
+			return m_installer->add(m_instance);
+		}
+		else
+			return m_installer->addLegacy(m_instance);
+	}
+	void reload()
+	{
+		try
+		{
+			m_instance->reloadProfile();
+			emitSucceeded();
+		}
+		catch (Exception &e)
+		{
+			emitFailed(e.cause());
+		}
+		catch (...)
+		{
+			emitFailed(tr("Failed to load the version description file for reasons unknown."));
+		}
+	}
+
+private:
+	ForgeInstaller *m_installer;
+	OneSixInstance *m_instance;
+	BaseVersionPtr m_version;
+};
+
+Task *ForgeInstaller::createInstallTask(OneSixInstance *instance,
+													BaseVersionPtr version, QObject *parent)
+{
+	if (!version)
+	{
+		return nullptr;
+	}
+	m_forge_version = std::dynamic_pointer_cast<ForgeVersion>(version);
+	return new ForgeInstallTask(this, instance, version, parent);
+}
+
+#include "ForgeInstaller.moc"
diff --git a/libraries/logic/minecraft/forge/ForgeInstaller.h b/libraries/logic/minecraft/forge/ForgeInstaller.h
new file mode 100644
index 00000000..499a6fb3
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeInstaller.h
@@ -0,0 +1,52 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "BaseInstaller.h"
+
+#include <QString>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class VersionFile;
+class ForgeInstallTask;
+struct ForgeVersion;
+
+class MULTIMC_LOGIC_EXPORT ForgeInstaller : public BaseInstaller
+{
+	friend class ForgeInstallTask;
+public:
+	ForgeInstaller();
+	virtual ~ForgeInstaller(){}
+	virtual Task *createInstallTask(OneSixInstance *instance, BaseVersionPtr version, QObject *parent) override;
+	virtual QString id() const override { return "net.minecraftforge"; }
+
+protected:
+	void prepare(const QString &filename, const QString &universalUrl);
+	bool add(OneSixInstance *to) override;
+	bool addLegacy(OneSixInstance *to);
+
+private:
+	// the parsed version json, read from the installer
+	std::shared_ptr<VersionFile> m_forge_json;
+	// the actual forge version
+	std::shared_ptr<ForgeVersion> m_forge_version;
+	QString internalPath;
+	QString finalPath;
+	QString m_forgeVersionString;
+	QString m_universal_url;
+};
diff --git a/libraries/logic/minecraft/forge/ForgeVersion.cpp b/libraries/logic/minecraft/forge/ForgeVersion.cpp
new file mode 100644
index 00000000..b859a28c
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeVersion.cpp
@@ -0,0 +1,55 @@
+#include "ForgeVersion.h"
+#include "minecraft/VersionFilterData.h"
+#include <QObject>
+
+QString ForgeVersion::name()
+{
+	return "Forge " + jobbuildver;
+}
+
+QString ForgeVersion::descriptor()
+{
+	return universal_filename;
+}
+
+QString ForgeVersion::typeString() const
+{
+	if (is_recommended)
+		return QObject::tr("Recommended");
+	return QString();
+}
+
+bool ForgeVersion::operator<(BaseVersion &a)
+{
+	ForgeVersion *pa = dynamic_cast<ForgeVersion *>(&a);
+	if (!pa)
+		return true;
+	return m_buildnr < pa->m_buildnr;
+}
+
+bool ForgeVersion::operator>(BaseVersion &a)
+{
+	ForgeVersion *pa = dynamic_cast<ForgeVersion *>(&a);
+	if (!pa)
+		return false;
+	return m_buildnr > pa->m_buildnr;
+}
+
+bool ForgeVersion::usesInstaller()
+{
+	if(installer_url.isEmpty())
+		return false;
+	if(g_VersionFilterData.forgeInstallerBlacklist.contains(mcver))
+		return false;
+	return true;
+}
+
+QString ForgeVersion::filename()
+{
+	return usesInstaller() ? installer_filename : universal_filename;
+}
+
+QString ForgeVersion::url()
+{
+	return usesInstaller() ? installer_url : universal_url;
+}
diff --git a/libraries/logic/minecraft/forge/ForgeVersion.h b/libraries/logic/minecraft/forge/ForgeVersion.h
new file mode 100644
index 00000000..e77d32f1
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeVersion.h
@@ -0,0 +1,42 @@
+#pragma once
+#include <QString>
+#include <memory>
+#include "BaseVersion.h"
+
+struct ForgeVersion;
+typedef std::shared_ptr<ForgeVersion> ForgeVersionPtr;
+
+struct ForgeVersion : public BaseVersion
+{
+	virtual QString descriptor() override;
+	virtual QString name() override;
+	virtual QString typeString() const override;
+	virtual bool operator<(BaseVersion &a) override;
+	virtual bool operator>(BaseVersion &a) override;
+
+	QString filename();
+	QString url();
+	
+	enum
+	{
+		Invalid,
+		Legacy,
+		Gradle
+	} type = Invalid;
+	
+	bool usesInstaller();
+
+	int m_buildnr = 0;
+	QString branch;
+	QString universal_url;
+	QString changelog_url;
+	QString installer_url;
+	QString jobbuildver;
+	QString mcver;
+	QString mcver_sane;
+	QString universal_filename;
+	QString installer_filename;
+	bool is_recommended = false;
+};
+
+Q_DECLARE_METATYPE(ForgeVersionPtr)
diff --git a/libraries/logic/minecraft/forge/ForgeVersionList.cpp b/libraries/logic/minecraft/forge/ForgeVersionList.cpp
new file mode 100644
index 00000000..de185e5f
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeVersionList.cpp
@@ -0,0 +1,450 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ForgeVersionList.h"
+#include "ForgeVersion.h"
+
+#include "net/NetJob.h"
+#include "net/URLConstants.h"
+#include "Env.h"
+
+#include <QtNetwork>
+#include <QtXml>
+#include <QRegExp>
+
+#include <QDebug>
+
+ForgeVersionList::ForgeVersionList(QObject *parent) : BaseVersionList(parent)
+{
+}
+
+Task *ForgeVersionList::getLoadTask()
+{
+	return new ForgeListLoadTask(this);
+}
+
+bool ForgeVersionList::isLoaded()
+{
+	return m_loaded;
+}
+
+const BaseVersionPtr ForgeVersionList::at(int i) const
+{
+	return m_vlist.at(i);
+}
+
+int ForgeVersionList::count() const
+{
+	return m_vlist.count();
+}
+
+int ForgeVersionList::columnCount(const QModelIndex &parent) const
+{
+	return 1;
+}
+
+QVariant ForgeVersionList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	auto version = std::dynamic_pointer_cast<ForgeVersion>(m_vlist[index.row()]);
+	switch (role)
+	{
+	case VersionPointerRole:
+		return qVariantFromValue(m_vlist[index.row()]);
+
+	case VersionRole:
+		return version->name();
+
+	case VersionIdRole:
+		return version->descriptor();
+
+	case ParentGameVersionRole:
+		return version->mcver_sane;
+
+	case RecommendedRole:
+		return version->is_recommended;
+
+	case BranchRole:
+		return version->branch;
+
+	default:
+		return QVariant();
+	}
+}
+
+BaseVersionList::RoleList ForgeVersionList::providesRoles() const
+{
+	return {VersionPointerRole, VersionRole, VersionIdRole, ParentGameVersionRole, RecommendedRole, BranchRole};
+}
+
+BaseVersionPtr ForgeVersionList::getLatestStable() const
+{
+	return BaseVersionPtr();
+}
+
+void ForgeVersionList::updateListData(QList<BaseVersionPtr> versions)
+{
+	beginResetModel();
+	m_vlist = versions;
+	m_loaded = true;
+	endResetModel();
+	// NOW SORT!!
+	// sort();
+}
+
+void ForgeVersionList::sortVersions()
+{
+	// NO-OP for now
+}
+
+ForgeListLoadTask::ForgeListLoadTask(ForgeVersionList *vlist) : Task()
+{
+	m_list = vlist;
+}
+
+void ForgeListLoadTask::executeTask()
+{
+	setStatus(tr("Fetching Forge version lists..."));
+	auto job = new NetJob("Version index");
+	// we do not care if the version is stale or not.
+	auto forgeListEntry = ENV.metacache()->resolveEntry("minecraftforge", "list.json");
+	auto gradleForgeListEntry = ENV.metacache()->resolveEntry("minecraftforge", "json");
+
+	// verify by poking the server.
+	forgeListEntry->setStale(true);
+	gradleForgeListEntry->setStale(true);
+
+	job->addNetAction(listDownload = CacheDownload::make(QUrl(URLConstants::FORGE_LEGACY_URL),
+														 forgeListEntry));
+	job->addNetAction(gradleListDownload = CacheDownload::make(
+						  QUrl(URLConstants::FORGE_GRADLE_URL), gradleForgeListEntry));
+
+	connect(listDownload.get(), SIGNAL(failed(int)), SLOT(listFailed()));
+	connect(gradleListDownload.get(), SIGNAL(failed(int)), SLOT(gradleListFailed()));
+
+	listJob.reset(job);
+	connect(listJob.get(), SIGNAL(succeeded()), SLOT(listDownloaded()));
+	connect(listJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	listJob->start();
+}
+
+bool ForgeListLoadTask::abort()
+{
+	return listJob->abort();
+}
+
+bool ForgeListLoadTask::parseForgeList(QList<BaseVersionPtr> &out)
+{
+	QByteArray data;
+	{
+		auto dlJob = listDownload;
+		auto filename = std::dynamic_pointer_cast<CacheDownload>(dlJob)->getTargetFilepath();
+		QFile listFile(filename);
+		if (!listFile.open(QIODevice::ReadOnly))
+		{
+			return false;
+		}
+		data = listFile.readAll();
+		dlJob.reset();
+	}
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		emitFailed("Error parsing version list JSON:" + jsonError.errorString());
+		return false;
+	}
+
+	if (!jsonDoc.isObject())
+	{
+		emitFailed("Error parsing version list JSON: JSON root is not an object");
+		return false;
+	}
+
+	QJsonObject root = jsonDoc.object();
+
+	// Now, get the array of versions.
+	if (!root.value("builds").isArray())
+	{
+		emitFailed(
+			"Error parsing version list JSON: version list object is missing 'builds' array");
+		return false;
+	}
+	QJsonArray builds = root.value("builds").toArray();
+
+	for (int i = 0; i < builds.count(); i++)
+	{
+		// Load the version info.
+		if (!builds[i].isObject())
+		{
+			// FIXME: log this somewhere
+			continue;
+		}
+		QJsonObject obj = builds[i].toObject();
+		int build_nr = obj.value("build").toDouble(0);
+		if (!build_nr)
+			continue;
+		QJsonArray files = obj.value("files").toArray();
+		QString url, jobbuildver, mcver, buildtype, universal_filename;
+		QString changelog_url, installer_url;
+		QString installer_filename;
+		bool valid = false;
+		for (int j = 0; j < files.count(); j++)
+		{
+			if (!files[j].isObject())
+			{
+				continue;
+			}
+			QJsonObject file = files[j].toObject();
+			buildtype = file.value("buildtype").toString();
+			if ((buildtype == "client" || buildtype == "universal") && !valid)
+			{
+				mcver = file.value("mcver").toString();
+				url = file.value("url").toString();
+				jobbuildver = file.value("jobbuildver").toString();
+				int lastSlash = url.lastIndexOf('/');
+				universal_filename = url.mid(lastSlash + 1);
+				valid = true;
+			}
+			else if (buildtype == "changelog")
+			{
+				QString ext = file.value("ext").toString();
+				if (ext.isEmpty())
+				{
+					continue;
+				}
+				changelog_url = file.value("url").toString();
+			}
+			else if (buildtype == "installer")
+			{
+				installer_url = file.value("url").toString();
+				int lastSlash = installer_url.lastIndexOf('/');
+				installer_filename = installer_url.mid(lastSlash + 1);
+			}
+		}
+		if (valid)
+		{
+			// Now, we construct the version object and add it to the list.
+			std::shared_ptr<ForgeVersion> fVersion(new ForgeVersion());
+			fVersion->universal_url = url;
+			fVersion->changelog_url = changelog_url;
+			fVersion->installer_url = installer_url;
+			fVersion->jobbuildver = jobbuildver;
+			fVersion->mcver = fVersion->mcver_sane = mcver;
+			fVersion->installer_filename = installer_filename;
+			fVersion->universal_filename = universal_filename;
+			fVersion->m_buildnr = build_nr;
+			fVersion->type = ForgeVersion::Legacy;
+			out.append(fVersion);
+		}
+	}
+
+	return true;
+}
+
+bool ForgeListLoadTask::parseForgeGradleList(QList<BaseVersionPtr> &out)
+{
+	QMap<int, std::shared_ptr<ForgeVersion>> lookup;
+	QByteArray data;
+	{
+		auto dlJob = gradleListDownload;
+		auto filename = std::dynamic_pointer_cast<CacheDownload>(dlJob)->getTargetFilepath();
+		QFile listFile(filename);
+		if (!listFile.open(QIODevice::ReadOnly))
+		{
+			return false;
+		}
+		data = listFile.readAll();
+		dlJob.reset();
+	}
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		emitFailed("Error parsing gradle version list JSON:" + jsonError.errorString());
+		return false;
+	}
+
+	if (!jsonDoc.isObject())
+	{
+		emitFailed("Error parsing gradle version list JSON: JSON root is not an object");
+		return false;
+	}
+
+	QJsonObject root = jsonDoc.object();
+
+	// we probably could hard code these, but it might still be worth doing it this way
+	const QString webpath = root.value("webpath").toString();
+	const QString artifact = root.value("artifact").toString();
+
+	QJsonObject numbers = root.value("number").toObject();
+	for (auto it = numbers.begin(); it != numbers.end(); ++it)
+	{
+		QJsonObject number = it.value().toObject();
+		std::shared_ptr<ForgeVersion> fVersion(new ForgeVersion());
+		fVersion->m_buildnr = number.value("build").toDouble();
+		if(fVersion->m_buildnr >= 953 && fVersion->m_buildnr <= 965)
+		{
+			qDebug() << fVersion->m_buildnr;
+		}
+		fVersion->jobbuildver = number.value("version").toString();
+		fVersion->branch = number.value("branch").toString("");
+		fVersion->mcver = number.value("mcversion").toString();
+		fVersion->universal_filename = "";
+		fVersion->installer_filename = "";
+		// HACK: here, we fix the minecraft version used by forge.
+		// HACK: this will inevitably break (later)
+		// FIXME: replace with a dictionary
+		fVersion->mcver_sane = fVersion->mcver;
+		fVersion->mcver_sane.replace("_pre", "-pre");
+
+		QString universal_filename, installer_filename;
+		QJsonArray files = number.value("files").toArray();
+		for (auto fIt = files.begin(); fIt != files.end(); ++fIt)
+		{
+			// TODO with gradle we also get checksums, use them
+			QJsonArray file = (*fIt).toArray();
+			if (file.size() < 3)
+			{
+				continue;
+			}
+
+			QString extension = file.at(0).toString();
+			QString part = file.at(1).toString();
+			QString checksum = file.at(2).toString();
+
+			// insane form of mcver is used here
+			QString longVersion = fVersion->mcver + "-" + fVersion->jobbuildver;
+			if (!fVersion->branch.isEmpty())
+			{
+				longVersion = longVersion + "-" + fVersion->branch;
+			}
+			QString filename = artifact + "-" + longVersion + "-" + part + "." + extension;
+
+			QString url = QString("%1/%2/%3")
+							  .arg(webpath)
+							  .arg(longVersion)
+							  .arg(filename);
+
+			if (part == "installer")
+			{
+				fVersion->installer_url = url;
+				installer_filename = filename;
+			}
+			else if (part == "universal")
+			{
+				fVersion->universal_url = url;
+				universal_filename = filename;
+			}
+			else if (part == "changelog")
+			{
+				fVersion->changelog_url = url;
+			}
+		}
+		if (fVersion->installer_url.isEmpty() && fVersion->universal_url.isEmpty())
+		{
+			continue;
+		}
+		fVersion->universal_filename = universal_filename;
+		fVersion->installer_filename = installer_filename;
+		fVersion->type = ForgeVersion::Gradle;
+		out.append(fVersion);
+		lookup[fVersion->m_buildnr] = fVersion;
+	}
+	QJsonObject promos = root.value("promos").toObject();
+	for (auto it = promos.begin(); it != promos.end(); ++it)
+	{
+		QString key = it.key();
+		int build = it.value().toInt();
+		QRegularExpression regexp("^(?<mcversion>[0-9]+(.[0-9]+)*)-(?<label>[a-z]+)$");
+		auto match = regexp.match(key);
+		if(!match.hasMatch())
+		{
+			qDebug() << key << "doesn't match." << "build" << build;
+			continue;
+		}
+
+		QString label = match.captured("label");
+		if(label != "recommended")
+		{
+			continue;
+		}
+		QString mcversion = match.captured("mcversion");
+		qDebug() << "Forge build" << build << "is the" << label << "for Minecraft" << mcversion << QString("<%1>").arg(key);
+		lookup[build]->is_recommended = true;
+	}
+	return true;
+}
+
+void ForgeListLoadTask::listDownloaded()
+{
+	QList<BaseVersionPtr> list;
+	bool ret = true;
+	if (!parseForgeList(list))
+	{
+		ret = false;
+	}
+	if (!parseForgeGradleList(list))
+	{
+		ret = false;
+	}
+
+	if (!ret)
+	{
+		return;
+	}
+	std::sort(list.begin(), list.end(), [](const BaseVersionPtr & l, const BaseVersionPtr & r)
+	{ return (*l > *r); });
+
+	m_list->updateListData(list);
+
+	emitSucceeded();
+	return;
+}
+
+void ForgeListLoadTask::listFailed()
+{
+	auto &reply = listDownload->m_reply;
+	if (reply)
+	{
+		qCritical() << "Getting forge version list failed: " << reply->errorString();
+	}
+	else
+	{
+		qCritical() << "Getting forge version list failed for reasons unknown.";
+	}
+}
+
+void ForgeListLoadTask::gradleListFailed()
+{
+	auto &reply = gradleListDownload->m_reply;
+	if (reply)
+	{
+		qCritical() << "Getting forge version list failed: " << reply->errorString();
+	}
+	else
+	{
+		qCritical() << "Getting forge version list failed for reasons unknown.";
+	}
+}
diff --git a/libraries/logic/minecraft/forge/ForgeVersionList.h b/libraries/logic/minecraft/forge/ForgeVersionList.h
new file mode 100644
index 00000000..62c08b2a
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeVersionList.h
@@ -0,0 +1,90 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "ForgeVersion.h"
+
+#include <QObject>
+#include <QAbstractListModel>
+#include <QUrl>
+#include <QNetworkReply>
+
+#include "BaseVersionList.h"
+#include "tasks/Task.h"
+#include "net/NetJob.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT ForgeVersionList : public BaseVersionList
+{
+	Q_OBJECT
+public:
+	friend class ForgeListLoadTask;
+
+	explicit ForgeVersionList(QObject *parent = 0);
+
+	virtual Task *getLoadTask() override;
+	virtual bool isLoaded() override;
+	virtual const BaseVersionPtr at(int i) const override;
+	virtual int count() const override;
+	virtual void sortVersions() override;
+
+	virtual BaseVersionPtr getLatestStable() const override;
+
+	ForgeVersionPtr findVersionByVersionNr(QString version);
+
+	virtual QVariant data(const QModelIndex &index, int role) const override;
+	virtual RoleList providesRoles() const override;
+
+	virtual int columnCount(const QModelIndex &parent) const override;
+
+protected:
+	QList<BaseVersionPtr> m_vlist;
+
+	bool m_loaded = false;
+
+protected
+slots:
+	virtual void updateListData(QList<BaseVersionPtr> versions) override;
+};
+
+class ForgeListLoadTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit ForgeListLoadTask(ForgeVersionList *vlist);
+
+	virtual void executeTask();
+	virtual bool abort();
+
+protected
+slots:
+	void listDownloaded();
+	void listFailed();
+	void gradleListFailed();
+
+protected:
+	NetJobPtr listJob;
+	ForgeVersionList *m_list;
+
+	CacheDownloadPtr listDownload;
+	CacheDownloadPtr gradleListDownload;
+
+private:
+	bool parseForgeList(QList<BaseVersionPtr> &out);
+	bool parseForgeGradleList(QList<BaseVersionPtr> &out);
+};
diff --git a/libraries/logic/minecraft/forge/ForgeXzDownload.cpp b/libraries/logic/minecraft/forge/ForgeXzDownload.cpp
new file mode 100644
index 00000000..adf96552
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeXzDownload.cpp
@@ -0,0 +1,358 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Env.h"
+#include "ForgeXzDownload.h"
+#include <FileSystem.h>
+
+#include <QCryptographicHash>
+#include <QFileInfo>
+#include <QDateTime>
+#include <QDir>
+#include <QDebug>
+
+ForgeXzDownload::ForgeXzDownload(QString relative_path, MetaEntryPtr entry) : NetAction()
+{
+	m_entry = entry;
+	m_target_path = entry->getFullPath();
+	m_pack200_xz_file.setFileTemplate("./dl_temp.XXXXXX");
+	m_status = Job_NotStarted;
+	m_url_path = relative_path;
+	m_url = "http://files.minecraftforge.net/maven/" + m_url_path + ".pack.xz";
+}
+
+void ForgeXzDownload::start()
+{
+	m_status = Job_InProgress;
+	if (!m_entry->isStale())
+	{
+		m_status = Job_Finished;
+		emit succeeded(m_index_within_job);
+		return;
+	}
+	// can we actually create the real, final file?
+	if (!FS::ensureFilePathExists(m_target_path))
+	{
+		m_status = Job_Failed;
+		emit failed(m_index_within_job);
+		return;
+	}
+
+	qDebug() << "Downloading " << m_url.toString();
+	QNetworkRequest request(m_url);
+	request.setRawHeader(QString("If-None-Match").toLatin1(), m_entry->getETag().toLatin1());
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Cached)");
+
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->get(request);
+
+	m_reply.reset(rep);
+	connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
+			SLOT(downloadProgress(qint64, qint64)));
+	connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
+			SLOT(downloadError(QNetworkReply::NetworkError)));
+	connect(rep, SIGNAL(readyRead()), SLOT(downloadReadyRead()));
+}
+
+void ForgeXzDownload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
+{
+	m_total_progress = bytesTotal;
+	m_progress = bytesReceived;
+	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
+}
+
+void ForgeXzDownload::downloadError(QNetworkReply::NetworkError error)
+{
+	// error happened during download.
+	// TODO: log the reason why
+	m_status = Job_Failed;
+}
+
+void ForgeXzDownload::failAndTryNextMirror()
+{
+	m_status = Job_Failed;
+	emit failed(m_index_within_job);
+}
+
+void ForgeXzDownload::downloadFinished()
+{
+	// if the download succeeded
+	if (m_status != Job_Failed)
+	{
+		// nothing went wrong...
+		m_status = Job_Finished;
+		if (m_pack200_xz_file.isOpen())
+		{
+			// we actually downloaded something! process and isntall it
+			decompressAndInstall();
+			return;
+		}
+		else
+		{
+			// something bad happened -- on the local machine!
+			m_status = Job_Failed;
+			m_pack200_xz_file.remove();
+			m_reply.reset();
+			emit failed(m_index_within_job);
+			return;
+		}
+	}
+	// else the download failed
+	else
+	{
+		m_status = Job_Failed;
+		m_pack200_xz_file.close();
+		m_pack200_xz_file.remove();
+		m_reply.reset();
+		failAndTryNextMirror();
+		return;
+	}
+}
+
+void ForgeXzDownload::downloadReadyRead()
+{
+
+	if (!m_pack200_xz_file.isOpen())
+	{
+		if (!m_pack200_xz_file.open())
+		{
+			/*
+			* Can't open the file... the job failed
+			*/
+			m_reply->abort();
+			emit failed(m_index_within_job);
+			return;
+		}
+	}
+	m_pack200_xz_file.write(m_reply->readAll());
+}
+
+#include "xz.h"
+#include "unpack200.h"
+#include <stdexcept>
+#include <unistd.h>
+
+const size_t buffer_size = 8196;
+
+void ForgeXzDownload::decompressAndInstall()
+{
+	// rewind the downloaded temp file
+	m_pack200_xz_file.seek(0);
+	// de-xz'd file
+	QTemporaryFile pack200_file("./dl_temp.XXXXXX");
+	pack200_file.open();
+
+	bool xz_success = false;
+	// first, de-xz
+	{
+		uint8_t in[buffer_size];
+		uint8_t out[buffer_size];
+		struct xz_buf b;
+		struct xz_dec *s;
+		enum xz_ret ret;
+		xz_crc32_init();
+		xz_crc64_init();
+		s = xz_dec_init(XZ_DYNALLOC, 1 << 26);
+		if (s == nullptr)
+		{
+			xz_dec_end(s);
+			failAndTryNextMirror();
+			return;
+		}
+		b.in = in;
+		b.in_pos = 0;
+		b.in_size = 0;
+		b.out = out;
+		b.out_pos = 0;
+		b.out_size = buffer_size;
+		while (!xz_success)
+		{
+			if (b.in_pos == b.in_size)
+			{
+				b.in_size = m_pack200_xz_file.read((char *)in, sizeof(in));
+				b.in_pos = 0;
+			}
+
+			ret = xz_dec_run(s, &b);
+
+			if (b.out_pos == sizeof(out))
+			{
+				if (pack200_file.write((char *)out, b.out_pos) != b.out_pos)
+				{
+					// msg = "Write error\n";
+					xz_dec_end(s);
+					failAndTryNextMirror();
+					return;
+				}
+
+				b.out_pos = 0;
+			}
+
+			if (ret == XZ_OK)
+				continue;
+
+			if (ret == XZ_UNSUPPORTED_CHECK)
+			{
+				// unsupported check. this is OK, but we should log this
+				continue;
+			}
+
+			if (pack200_file.write((char *)out, b.out_pos) != b.out_pos)
+			{
+				// write error
+				pack200_file.close();
+				xz_dec_end(s);
+				return;
+			}
+
+			switch (ret)
+			{
+			case XZ_STREAM_END:
+				xz_dec_end(s);
+				xz_success = true;
+				break;
+
+			case XZ_MEM_ERROR:
+				qCritical() << "Memory allocation failed\n";
+				xz_dec_end(s);
+				failAndTryNextMirror();
+				return;
+
+			case XZ_MEMLIMIT_ERROR:
+				qCritical() << "Memory usage limit reached\n";
+				xz_dec_end(s);
+				failAndTryNextMirror();
+				return;
+
+			case XZ_FORMAT_ERROR:
+				qCritical() << "Not a .xz file\n";
+				xz_dec_end(s);
+				failAndTryNextMirror();
+				return;
+
+			case XZ_OPTIONS_ERROR:
+				qCritical() << "Unsupported options in the .xz headers\n";
+				xz_dec_end(s);
+				failAndTryNextMirror();
+				return;
+
+			case XZ_DATA_ERROR:
+			case XZ_BUF_ERROR:
+				qCritical() << "File is corrupt\n";
+				xz_dec_end(s);
+				failAndTryNextMirror();
+				return;
+
+			default:
+				qCritical() << "Bug!\n";
+				xz_dec_end(s);
+				failAndTryNextMirror();
+				return;
+			}
+		}
+	}
+	m_pack200_xz_file.remove();
+
+	// revert pack200
+	pack200_file.seek(0);
+	int handle_in = pack200_file.handle();
+	// FIXME: dispose of file handles, pointers and the like. Ideally wrap in objects.
+	if(handle_in == -1)
+	{
+		qCritical() << "Error reopening " << pack200_file.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	int handle_in_dup = dup (handle_in);
+	if(handle_in_dup == -1)
+	{
+		qCritical() << "Error reopening " << pack200_file.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	FILE *file_in = fdopen (handle_in_dup, "rb");
+	if(!file_in)
+	{
+		qCritical() << "Error reopening " << pack200_file.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	QFile qfile_out(m_target_path);
+	if(!qfile_out.open(QIODevice::WriteOnly))
+	{
+		qCritical() << "Error opening " << qfile_out.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	int handle_out = qfile_out.handle();
+	if(handle_out == -1)
+	{
+		qCritical() << "Error opening " << qfile_out.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	int handle_out_dup = dup (handle_out);
+	if(handle_out_dup == -1)
+	{
+		qCritical() << "Error reopening " << qfile_out.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	FILE *file_out = fdopen (handle_out_dup, "wb");
+	if(!file_out)
+	{
+		qCritical() << "Error opening " << qfile_out.fileName();
+		failAndTryNextMirror();
+		return;
+	}
+	try
+	{
+		// NOTE: this takes ownership of both FILE pointers. That's why we duplicate them above.
+		unpack_200(file_in, file_out);
+	}
+	catch (std::runtime_error &err)
+	{
+		m_status = Job_Failed;
+		qCritical() << "Error unpacking " << pack200_file.fileName() << " : " << err.what();
+		QFile f(m_target_path);
+		if (f.exists())
+			f.remove();
+		failAndTryNextMirror();
+		return;
+	}
+	pack200_file.remove();
+
+	QFile jar_file(m_target_path);
+
+	if (!jar_file.open(QIODevice::ReadOnly))
+	{
+		jar_file.remove();
+		failAndTryNextMirror();
+		return;
+	}
+	auto hash = QCryptographicHash::hash(jar_file.readAll(), QCryptographicHash::Md5);
+	m_entry->setMD5Sum(hash.toHex().constData());
+	jar_file.close();
+
+	QFileInfo output_file_info(m_target_path);
+	m_entry->setETag(m_reply->rawHeader("ETag").constData());
+	m_entry->setLocalChangedTimestamp(output_file_info.lastModified().toUTC().toMSecsSinceEpoch());
+	m_entry->setStale(false);
+	ENV.metacache()->updateEntry(m_entry);
+
+	m_reply.reset();
+	emit succeeded(m_index_within_job);
+}
diff --git a/libraries/logic/minecraft/forge/ForgeXzDownload.h b/libraries/logic/minecraft/forge/ForgeXzDownload.h
new file mode 100644
index 00000000..67524405
--- /dev/null
+++ b/libraries/logic/minecraft/forge/ForgeXzDownload.h
@@ -0,0 +1,59 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "net/NetAction.h"
+#include "net/HttpMetaCache.h"
+#include <QFile>
+#include <QTemporaryFile>
+
+typedef std::shared_ptr<class ForgeXzDownload> ForgeXzDownloadPtr;
+
+class ForgeXzDownload : public NetAction
+{
+	Q_OBJECT
+public:
+	MetaEntryPtr m_entry;
+	/// if saving to file, use the one specified in this string
+	QString m_target_path;
+	/// this is the output file, if any
+	QTemporaryFile m_pack200_xz_file;
+	/// path relative to the mirror base
+	QString m_url_path;
+
+public:
+	explicit ForgeXzDownload(QString relative_path, MetaEntryPtr entry);
+	static ForgeXzDownloadPtr make(QString relative_path, MetaEntryPtr entry)
+	{
+		return ForgeXzDownloadPtr(new ForgeXzDownload(relative_path, entry));
+	}
+	virtual ~ForgeXzDownload(){};
+
+protected
+slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	virtual void downloadError(QNetworkReply::NetworkError error);
+	virtual void downloadFinished();
+	virtual void downloadReadyRead();
+
+public
+slots:
+	virtual void start();
+
+private:
+	void decompressAndInstall();
+	void failAndTryNextMirror();
+};
diff --git a/libraries/logic/minecraft/forge/LegacyForge.cpp b/libraries/logic/minecraft/forge/LegacyForge.cpp
new file mode 100644
index 00000000..aa2c8063
--- /dev/null
+++ b/libraries/logic/minecraft/forge/LegacyForge.cpp
@@ -0,0 +1,56 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LegacyForge.h"
+
+MinecraftForge::MinecraftForge(const QString &file) : Mod(file)
+{
+}
+
+bool MinecraftForge::FixVersionIfNeeded(QString newVersion)
+{/*
+	wxString reportedVersion = GetModVersion();
+	if(reportedVersion == "..." || reportedVersion.empty())
+	{
+		std::auto_ptr<wxFFileInputStream> in(new wxFFileInputStream("forge.zip"));
+		wxTempFileOutputStream out("forge.zip");
+		wxTextOutputStream textout(out);
+		wxZipInputStream inzip(*in);
+		wxZipOutputStream outzip(out);
+		std::auto_ptr<wxZipEntry> entry;
+		// preserve metadata
+		outzip.CopyArchiveMetaData(inzip);
+		// copy all entries
+		while (entry.reset(inzip.GetNextEntry()), entry.get() != NULL)
+			if (!outzip.CopyEntry(entry.release(), inzip))
+				return false;
+		// release last entry
+		in.reset();
+		outzip.PutNextEntry("forgeversion.properties");
+
+		wxStringTokenizer tokenizer(newVersion,".");
+		wxString verFile;
+		verFile << wxString("forge.major.number=") << tokenizer.GetNextToken() << "\n";
+		verFile << wxString("forge.minor.number=") << tokenizer.GetNextToken() << "\n";
+		verFile << wxString("forge.revision.number=") << tokenizer.GetNextToken() << "\n";
+		verFile << wxString("forge.build.number=") << tokenizer.GetNextToken() << "\n";
+		auto buf = verFile.ToUTF8();
+		outzip.Write(buf.data(), buf.length());
+		// check if we succeeded
+		return inzip.Eof() && outzip.Close() && out.Commit();
+	}
+	*/
+	return true;
+}
diff --git a/libraries/logic/minecraft/forge/LegacyForge.h b/libraries/logic/minecraft/forge/LegacyForge.h
new file mode 100644
index 00000000..f51d5e85
--- /dev/null
+++ b/libraries/logic/minecraft/forge/LegacyForge.h
@@ -0,0 +1,25 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "minecraft/Mod.h"
+
+class MinecraftForge : public Mod
+{
+public:
+	MinecraftForge(const QString &file);
+	bool FixVersionIfNeeded(QString newVersion);
+};
diff --git a/libraries/logic/minecraft/ftb/FTBPlugin.cpp b/libraries/logic/minecraft/ftb/FTBPlugin.cpp
new file mode 100644
index 00000000..a142c106
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/FTBPlugin.cpp
@@ -0,0 +1,395 @@
+#include "FTBPlugin.h"
+#include <Env.h>
+#include "FTBVersion.h"
+#include "LegacyFTBInstance.h"
+#include "OneSixFTBInstance.h"
+#include <BaseInstance.h>
+#include <InstanceList.h>
+#include <minecraft/MinecraftVersionList.h>
+#include <settings/INISettingsObject.h>
+#include <FileSystem.h>
+#include "QDebug"
+#include <QXmlStreamReader>
+#include <QRegularExpression>
+
+struct FTBRecord
+{
+	QString dirName;
+	QString name;
+	QString logo;
+	QString iconKey;
+	QString mcVersion;
+	QString description;
+	QString instanceDir;
+	QString templateDir;
+	bool operator==(const FTBRecord other) const
+	{
+		return instanceDir == other.instanceDir;
+	}
+};
+
+inline uint qHash(FTBRecord record)
+{
+	return qHash(record.instanceDir);
+}
+
+QSet<FTBRecord> discoverFTBInstances(SettingsObjectPtr globalSettings)
+{
+	QSet<FTBRecord> records;
+	QDir dir = QDir(globalSettings->get("FTBLauncherLocal").toString());
+	QDir dataDir = QDir(globalSettings->get("FTBRoot").toString());
+	if (!dataDir.exists())
+	{
+		qDebug() << "The FTB directory specified does not exist. Please check your settings";
+		return records;
+	}
+	else if (!dir.exists())
+	{
+		qDebug() << "The FTB launcher data directory specified does not exist. Please check "
+					"your settings";
+		return records;
+	}
+	dir.cd("ModPacks");
+	auto allFiles = dir.entryList(QDir::Readable | QDir::Files, QDir::Name);
+	for (auto filename : allFiles)
+	{
+		if (!filename.endsWith(".xml"))
+			continue;
+		auto fpath = dir.absoluteFilePath(filename);
+		QFile f(fpath);
+		qDebug() << "Discovering FTB instances -- " << fpath;
+		if (!f.open(QFile::ReadOnly))
+			continue;
+
+		// read the FTB packs XML.
+		QXmlStreamReader reader(&f);
+		while (!reader.atEnd())
+		{
+			switch (reader.readNext())
+			{
+			case QXmlStreamReader::StartElement:
+			{
+				if (reader.name() == "modpack")
+				{
+					QXmlStreamAttributes attrs = reader.attributes();
+					FTBRecord record;
+					record.dirName = attrs.value("dir").toString();
+					record.instanceDir = dataDir.absoluteFilePath(record.dirName);
+					record.templateDir = dir.absoluteFilePath(record.dirName);
+					QDir test(record.instanceDir);
+					qDebug() << dataDir.absolutePath() << record.instanceDir << record.dirName;
+					if (!test.exists())
+						continue;
+					record.name = attrs.value("name").toString();
+					record.logo = attrs.value("logo").toString();
+					QString logo = record.logo;
+					record.iconKey = logo.remove(QRegularExpression("\\..*"));
+					auto customVersions = attrs.value("customMCVersions");
+					if (!customVersions.isNull())
+					{
+						QMap<QString, QString> versionMatcher;
+						QString customVersionsStr = customVersions.toString();
+						QStringList list = customVersionsStr.split(';');
+						for (auto item : list)
+						{
+							auto segment = item.split('^');
+							if (segment.size() != 2)
+							{
+								qCritical() << "FTB: Segment of size < 2 in "
+											<< customVersionsStr;
+								continue;
+							}
+							versionMatcher[segment[0]] = segment[1];
+						}
+						auto actualVersion = attrs.value("version").toString();
+						if (versionMatcher.contains(actualVersion))
+						{
+							record.mcVersion = versionMatcher[actualVersion];
+						}
+						else
+						{
+							record.mcVersion = attrs.value("mcVersion").toString();
+						}
+					}
+					else
+					{
+						record.mcVersion = attrs.value("mcVersion").toString();
+					}
+					record.description = attrs.value("description").toString();
+					records.insert(record);
+				}
+				break;
+			}
+			case QXmlStreamReader::EndElement:
+				break;
+			case QXmlStreamReader::Characters:
+				break;
+			default:
+				break;
+			}
+		}
+		f.close();
+	}
+	return records;
+}
+
+InstancePtr loadInstance(SettingsObjectPtr globalSettings, QMap<QString, QString> &groupMap, const FTBRecord & record)
+{
+	InstancePtr inst;
+
+	auto m_settings = std::make_shared<INISettingsObject>(FS::PathCombine(record.instanceDir, "instance.cfg"));
+	m_settings->registerSetting("InstanceType", "Legacy");
+
+	qDebug() << "Loading existing " << record.name;
+
+	QString inst_type = m_settings->get("InstanceType").toString();
+	if (inst_type == "LegacyFTB")
+	{
+		inst.reset(new LegacyFTBInstance(globalSettings, m_settings, record.instanceDir));
+	}
+	else if (inst_type == "OneSixFTB")
+	{
+		inst.reset(new OneSixFTBInstance(globalSettings, m_settings, record.instanceDir));
+	}
+	else
+	{
+		return nullptr;
+	}
+	qDebug() << "Construction " << record.instanceDir;
+
+	SettingsObject::Lock lock(inst->settings());
+	inst->init();
+	qDebug() << "Init " << record.instanceDir;
+	inst->setGroupInitial("FTB");
+	/**
+	 * FIXME: this does not respect the user's preferences. BUT, it would work nicely with the planned pack support
+	 *        -> instead of changing the user values, change pack values (defaults you can look at and revert to)
+	 */
+	/*
+	inst->setName(record.name);
+	inst->setIconKey(record.iconKey);
+	inst->setNotes(record.description);
+	*/
+	if (inst->intendedVersionId() != record.mcVersion)
+	{
+		inst->setIntendedVersionId(record.mcVersion);
+	}
+	qDebug() << "Post-Process " << record.instanceDir;
+	if (!InstanceList::continueProcessInstance(inst, InstanceList::NoCreateError, record.instanceDir, groupMap))
+	{
+		return nullptr;
+	}
+	qDebug() << "Final " << record.instanceDir;
+	return inst;
+}
+
+InstancePtr createInstance(SettingsObjectPtr globalSettings, QMap<QString, QString> &groupMap, const FTBRecord & record)
+{
+	QDir rootDir(record.instanceDir);
+
+	InstancePtr inst;
+
+	qDebug() << "Converting " << record.name << " as new.";
+
+	auto mcVersion = std::dynamic_pointer_cast<MinecraftVersion>(ENV.getVersion("net.minecraft", record.mcVersion));
+	if (!mcVersion)
+	{
+		qCritical() << "Can't load instance " << record.instanceDir
+					<< " because minecraft version " << record.mcVersion
+					<< " can't be resolved.";
+		return nullptr;
+	}
+
+	if (!rootDir.exists() && !rootDir.mkpath("."))
+	{
+		qCritical() << "Can't create instance folder" << record.instanceDir;
+		return nullptr;
+	}
+
+	auto m_settings = std::make_shared<INISettingsObject>(FS::PathCombine(record.instanceDir, "instance.cfg"));
+	m_settings->registerSetting("InstanceType", "Legacy");
+
+	if (mcVersion->usesLegacyLauncher())
+	{
+		m_settings->set("InstanceType", "LegacyFTB");
+		inst.reset(new LegacyFTBInstance(globalSettings, m_settings, record.instanceDir));
+	}
+	else
+	{
+		m_settings->set("InstanceType", "OneSixFTB");
+		inst.reset(new OneSixFTBInstance(globalSettings, m_settings, record.instanceDir));
+	}
+	// initialize
+	{
+		SettingsObject::Lock lock(inst->settings());
+		inst->setIntendedVersionId(mcVersion->descriptor());
+		inst->init();
+		inst->setGroupInitial("FTB");
+		inst->setName(record.name);
+		inst->setIconKey(record.iconKey);
+		inst->setNotes(record.description);
+		qDebug() << "Post-Process " << record.instanceDir;
+		if (!InstanceList::continueProcessInstance(inst, InstanceList::NoCreateError, record.instanceDir, groupMap))
+		{
+			return nullptr;
+		}
+	}
+	return inst;
+}
+
+void FTBPlugin::loadInstances(SettingsObjectPtr globalSettings, QMap<QString, QString> &groupMap, QList<InstancePtr> &tempList)
+{
+	// nothing to load when we don't have
+	if (globalSettings->get("TrackFTBInstances").toBool() != true)
+	{
+		return;
+	}
+
+	auto records = discoverFTBInstances(globalSettings);
+	if (!records.size())
+	{
+		qDebug() << "No FTB instances to load.";
+		return;
+	}
+	qDebug() << "Loading FTB instances! -- got " << records.size();
+	// process the records we acquired.
+	for (auto record : records)
+	{
+		qDebug() << "Loading FTB instance from " << record.instanceDir;
+		QString iconKey = record.iconKey;
+		// MMC->icons()->addIcon(iconKey, iconKey, FS::PathCombine(record.templateDir, record.logo), MMCIcon::Transient);
+		auto settingsFilePath = FS::PathCombine(record.instanceDir, "instance.cfg");
+		qDebug() << "ICON get!";
+
+		if (QFileInfo(settingsFilePath).exists())
+		{
+			auto instPtr = loadInstance(globalSettings, groupMap, record);
+			if (!instPtr)
+			{
+				qWarning() << "Couldn't load instance config:" << settingsFilePath;
+				if(!QFile::remove(settingsFilePath))
+				{
+					qWarning() << "Couldn't remove broken instance config!";
+					continue;
+				}
+				// failed to load, but removed the poisonous file
+			}
+			else
+			{
+				tempList.append(InstancePtr(instPtr));
+				continue;
+			}
+		}
+		auto instPtr = createInstance(globalSettings, groupMap, record);
+		if (!instPtr)
+		{
+			qWarning() << "Couldn't create FTB instance!";
+			continue;
+		}
+		tempList.append(InstancePtr(instPtr));
+	}
+}
+
+#ifdef Q_OS_WIN32
+#include <windows.h>
+static const int APPDATA_BUFFER_SIZE = 1024;
+#endif
+
+static QString getLocalCacheStorageLocation()
+{
+	QString ftbDefault;
+#ifdef Q_OS_WIN32
+	wchar_t buf[APPDATA_BUFFER_SIZE];
+	if (GetEnvironmentVariableW(L"LOCALAPPDATA", buf, APPDATA_BUFFER_SIZE)) // local
+	{
+		ftbDefault = QDir(QString::fromWCharArray(buf)).absoluteFilePath("ftblauncher");
+	}
+	else if (GetEnvironmentVariableW(L"APPDATA", buf, APPDATA_BUFFER_SIZE)) // roaming
+	{
+		ftbDefault = QDir(QString::fromWCharArray(buf)).absoluteFilePath("ftblauncher");
+	}
+	else
+	{
+		qCritical() << "Your LOCALAPPDATA and APPDATA folders are missing!"
+			" If you are on windows, this means your system is broken.";
+	}
+#elif defined(Q_OS_MAC)
+	ftbDefault = FS::PathCombine(QDir::homePath(), "Library/Application Support/ftblauncher");
+#else
+	ftbDefault = QDir::home().absoluteFilePath(".ftblauncher");
+#endif
+	return ftbDefault;
+}
+
+
+static QString getRoamingStorageLocation()
+{
+	QString ftbDefault;
+#ifdef Q_OS_WIN32
+	wchar_t buf[APPDATA_BUFFER_SIZE];
+	QString cacheStorage;
+	if (GetEnvironmentVariableW(L"APPDATA", buf, APPDATA_BUFFER_SIZE))
+	{
+		ftbDefault = QDir(QString::fromWCharArray(buf)).absoluteFilePath("ftblauncher");
+	}
+	else
+	{
+		qCritical() << "Your APPDATA folder is missing! If you are on windows, this means your system is broken.";
+	}
+#elif defined(Q_OS_MAC)
+	ftbDefault = FS::PathCombine(QDir::homePath(), "Library/Application Support/ftblauncher");
+#else
+	ftbDefault = QDir::home().absoluteFilePath(".ftblauncher");
+#endif
+	return ftbDefault;
+}
+
+void FTBPlugin::initialize(SettingsObjectPtr globalSettings)
+{
+	// FTB
+	globalSettings->registerSetting("TrackFTBInstances", false);
+	QString ftbRoaming = getRoamingStorageLocation();
+	QString ftbLocal = getLocalCacheStorageLocation();
+
+	globalSettings->registerSetting("FTBLauncherRoaming", ftbRoaming);
+	globalSettings->registerSetting("FTBLauncherLocal", ftbLocal);
+	qDebug() << "FTB Launcher paths:" << globalSettings->get("FTBLauncherRoaming").toString()
+			 << "and" << globalSettings->get("FTBLauncherLocal").toString();
+
+	globalSettings->registerSetting("FTBRoot");
+	if (globalSettings->get("FTBRoot").isNull())
+	{
+		QString ftbRoot;
+		QFile f(QDir(globalSettings->get("FTBLauncherRoaming").toString()).absoluteFilePath("ftblaunch.cfg"));
+		qDebug() << "Attempting to read" << f.fileName();
+		if (f.open(QFile::ReadOnly))
+		{
+			const QString data = QString::fromLatin1(f.readAll());
+			QRegularExpression exp("installPath=(.*)");
+			ftbRoot = QDir::cleanPath(exp.match(data).captured(1));
+#ifdef Q_OS_WIN32
+			if (!ftbRoot.isEmpty())
+			{
+				if (ftbRoot.at(0).isLetter() && ftbRoot.size() > 1 && ftbRoot.at(1) == '/')
+				{
+					ftbRoot.remove(1, 1);
+				}
+			}
+#endif
+			if (ftbRoot.isEmpty())
+			{
+				qDebug() << "Failed to get FTB root path";
+			}
+			else
+			{
+				qDebug() << "FTB is installed at" << ftbRoot;
+				globalSettings->set("FTBRoot", ftbRoot);
+			}
+		}
+		else
+		{
+			qWarning() << "Couldn't open" << f.fileName() << ":" << f.errorString();
+			qWarning() << "This is perfectly normal if you don't have FTB installed";
+		}
+	}
+}
diff --git a/libraries/logic/minecraft/ftb/FTBPlugin.h b/libraries/logic/minecraft/ftb/FTBPlugin.h
new file mode 100644
index 00000000..6851d8a5
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/FTBPlugin.h
@@ -0,0 +1,13 @@
+#pragma once
+
+#include <BaseInstance.h>
+
+#include "multimc_logic_export.h"
+
+// Pseudo-plugin for FTB related things. Super derpy!
+class MULTIMC_LOGIC_EXPORT FTBPlugin
+{
+public:
+	static void initialize(SettingsObjectPtr globalSettings);
+	static void loadInstances(SettingsObjectPtr globalSettings, QMap<QString, QString> &groupMap, QList<InstancePtr> &tempList);
+};
diff --git a/libraries/logic/minecraft/ftb/FTBProfileStrategy.cpp b/libraries/logic/minecraft/ftb/FTBProfileStrategy.cpp
new file mode 100644
index 00000000..f5faacae
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/FTBProfileStrategy.cpp
@@ -0,0 +1,128 @@
+#include "FTBProfileStrategy.h"
+#include "OneSixFTBInstance.h"
+
+#include "minecraft/VersionBuildError.h"
+#include "minecraft/MinecraftVersionList.h"
+#include <FileSystem.h>
+
+#include <QDir>
+#include <QUuid>
+#include <QJsonDocument>
+#include <QJsonArray>
+
+FTBProfileStrategy::FTBProfileStrategy(OneSixFTBInstance* instance) : OneSixProfileStrategy(instance)
+{
+}
+
+void FTBProfileStrategy::loadDefaultBuiltinPatches()
+{
+	// FIXME: this should be here, but it needs us to be able to deal with multiple libraries paths
+	// OneSixProfileStrategy::loadDefaultBuiltinPatches();
+	auto mcVersion = m_instance->intendedVersionId();
+	auto nativeInstance = dynamic_cast<OneSixFTBInstance *>(m_instance);
+
+	ProfilePatchPtr minecraftPatch;
+	{
+		auto mcJson = m_instance->versionsPath().absoluteFilePath(mcVersion + "/" + mcVersion + ".json");
+		// load up the base minecraft patch
+		if(QFile::exists(mcJson))
+		{
+			auto file = ProfileUtils::parseJsonFile(QFileInfo(mcJson), false);
+			file->fileId = "net.minecraft";
+			file->name = QObject::tr("Minecraft (tracked)");
+			file->setVanilla(true);
+			if(file->version.isEmpty())
+			{
+				file->version = mcVersion;
+			}
+			for(auto addLib: file->libraries)
+			{
+				addLib->setHint("local");
+				addLib->setStoragePrefix(nativeInstance->librariesPath().absolutePath());
+			}
+			minecraftPatch = std::dynamic_pointer_cast<ProfilePatch>(file);
+		}
+		else
+		{
+			throw VersionIncomplete("net.minecraft");
+		}
+		minecraftPatch->setOrder(-2);
+	}
+	profile->appendPatch(minecraftPatch);
+
+	ProfilePatchPtr packPatch;
+	{
+		auto mcJson = m_instance->minecraftRoot() + "/pack.json";
+		// load up the base minecraft patch
+		if(QFile::exists(mcJson))
+		{
+			auto file = ProfileUtils::parseJsonFile(QFileInfo(mcJson), false);
+
+			// adapt the loaded file - the FTB patch file format is different than ours.
+			file->minecraftVersion.clear();
+			for(auto addLib: file->libraries)
+			{
+				addLib->setHint("local");
+				addLib->setStoragePrefix(nativeInstance->librariesPath().absolutePath());
+			}
+			file->fileId = "org.multimc.ftb.pack";
+			file->setVanilla(true);
+			file->name = QObject::tr("%1 (FTB pack)").arg(m_instance->name());
+			if(file->version.isEmpty())
+			{
+				file->version = QObject::tr("Unknown");
+				QFile versionFile (FS::PathCombine(m_instance->instanceRoot(), "version"));
+				if(versionFile.exists())
+				{
+					if(versionFile.open(QIODevice::ReadOnly))
+					{
+						// FIXME: just guessing the encoding/charset here.
+						auto version = QString::fromUtf8(versionFile.readAll());
+						file->version = version;
+					}
+				}
+			}
+			packPatch = std::dynamic_pointer_cast<ProfilePatch>(file);
+		}
+		else
+		{
+			throw VersionIncomplete("org.multimc.ftb.pack");
+		}
+		packPatch->setOrder(1);
+	}
+	profile->appendPatch(packPatch);
+
+}
+
+void FTBProfileStrategy::load()
+{
+	profile->clearPatches();
+
+	loadDefaultBuiltinPatches();
+	loadUserPatches();
+}
+
+bool FTBProfileStrategy::saveOrder(ProfileUtils::PatchOrder order)
+{
+	return false;
+}
+
+bool FTBProfileStrategy::resetOrder()
+{
+	return false;
+}
+
+bool FTBProfileStrategy::installJarMods(QStringList filepaths)
+{
+	return false;
+}
+
+bool FTBProfileStrategy::customizePatch(ProfilePatchPtr patch)
+{
+	return false;
+}
+
+bool FTBProfileStrategy::revertPatch(ProfilePatchPtr patch)
+{
+	return false;
+}
diff --git a/libraries/logic/minecraft/ftb/FTBProfileStrategy.h b/libraries/logic/minecraft/ftb/FTBProfileStrategy.h
new file mode 100644
index 00000000..522af098
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/FTBProfileStrategy.h
@@ -0,0 +1,21 @@
+#pragma once
+#include "minecraft/ProfileStrategy.h"
+#include "minecraft/onesix/OneSixProfileStrategy.h"
+
+class OneSixFTBInstance;
+
+class FTBProfileStrategy : public OneSixProfileStrategy
+{
+public:
+	FTBProfileStrategy(OneSixFTBInstance * instance);
+	virtual ~FTBProfileStrategy() {};
+	virtual void load() override;
+	virtual bool resetOrder() override;
+	virtual bool saveOrder(ProfileUtils::PatchOrder order) override;
+	virtual bool installJarMods(QStringList filepaths) override;
+	virtual bool customizePatch (ProfilePatchPtr patch) override;
+	virtual bool revertPatch (ProfilePatchPtr patch) override;
+
+protected:
+	virtual void loadDefaultBuiltinPatches() override;
+};
diff --git a/libraries/logic/minecraft/ftb/FTBVersion.h b/libraries/logic/minecraft/ftb/FTBVersion.h
new file mode 100644
index 00000000..805319b4
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/FTBVersion.h
@@ -0,0 +1,32 @@
+#pragma once
+#include <minecraft/MinecraftVersion.h>
+
+class FTBVersion : public BaseVersion
+{
+public:
+	FTBVersion(MinecraftVersionPtr parent) : m_version(parent){};
+
+public:
+	virtual QString descriptor() override
+	{
+		return m_version->descriptor();
+	}
+
+	virtual QString name() override
+	{
+		return m_version->name();
+	}
+
+	virtual QString typeString() const override
+	{
+		return m_version->typeString();
+	}
+
+	MinecraftVersionPtr getMinecraftVersion()
+	{
+		return m_version;
+	}
+
+private:
+	MinecraftVersionPtr m_version;
+};
diff --git a/libraries/logic/minecraft/ftb/LegacyFTBInstance.cpp b/libraries/logic/minecraft/ftb/LegacyFTBInstance.cpp
new file mode 100644
index 00000000..a7091f1d
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/LegacyFTBInstance.cpp
@@ -0,0 +1,27 @@
+#include "LegacyFTBInstance.h"
+#include <settings/INISettingsObject.h>
+#include <QDir>
+
+LegacyFTBInstance::LegacyFTBInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir) :
+	LegacyInstance(globalSettings, settings, rootDir)
+{
+}
+
+QString LegacyFTBInstance::id() const
+{
+	return "FTB/" + BaseInstance::id();
+}
+
+void LegacyFTBInstance::copy(const QDir &newDir)
+{
+	// set the target instance to be plain Legacy
+	INISettingsObject settings_obj(newDir.absoluteFilePath("instance.cfg"));
+	settings_obj.registerSetting("InstanceType", "Legacy");
+	QString inst_type = settings_obj.get("InstanceType").toString();
+	settings_obj.set("InstanceType", "Legacy");
+}
+
+QString LegacyFTBInstance::typeName() const
+{
+	return tr("Legacy FTB");
+}
diff --git a/libraries/logic/minecraft/ftb/LegacyFTBInstance.h b/libraries/logic/minecraft/ftb/LegacyFTBInstance.h
new file mode 100644
index 00000000..7178bca4
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/LegacyFTBInstance.h
@@ -0,0 +1,17 @@
+#pragma once
+
+#include "minecraft/legacy/LegacyInstance.h"
+
+class LegacyFTBInstance : public LegacyInstance
+{
+	Q_OBJECT
+public:
+	explicit LegacyFTBInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+	virtual QString id() const;
+	virtual void copy(const QDir &newDir);
+	virtual QString typeName() const;
+	bool canExport() const override
+	{
+		return false;
+	}
+};
diff --git a/libraries/logic/minecraft/ftb/OneSixFTBInstance.cpp b/libraries/logic/minecraft/ftb/OneSixFTBInstance.cpp
new file mode 100644
index 00000000..81e939a1
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/OneSixFTBInstance.cpp
@@ -0,0 +1,138 @@
+#include "OneSixFTBInstance.h"
+#include "FTBProfileStrategy.h"
+
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/GradleSpecifier.h"
+#include "tasks/SequentialTask.h"
+#include <settings/INISettingsObject.h>
+#include <FileSystem.h>
+
+#include <QJsonArray>
+
+OneSixFTBInstance::OneSixFTBInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir) :
+	OneSixInstance(globalSettings, settings, rootDir)
+{
+	m_globalSettings = globalSettings;
+}
+
+void OneSixFTBInstance::copy(const QDir &newDir)
+{
+	QStringList libraryNames;
+	// create patch file
+	{
+		qDebug()<< "Creating patch file for FTB instance...";
+		QFile f(minecraftRoot() + "/pack.json");
+		if (!f.open(QFile::ReadOnly))
+		{
+			qCritical() << "Couldn't open" << f.fileName() << ":" << f.errorString();
+			return;
+		}
+		QJsonObject root = QJsonDocument::fromJson(f.readAll()).object();
+		QJsonArray libs = root.value("libraries").toArray();
+		QJsonArray outLibs;
+		for (auto lib : libs)
+		{
+			QJsonObject libObj = lib.toObject();
+			libObj.insert("MMC-hint", QString("local"));
+			libObj.insert("insert", QString("prepend"));
+			libraryNames.append(libObj.value("name").toString());
+			outLibs.append(libObj);
+		}
+		root.remove("libraries");
+		root.remove("id");
+
+		// HACK HACK HACK HACK
+		// A workaround for a problem in MultiMC, triggered by a historical problem in FTB,
+		// triggered by Mojang getting their library versions wrong in 1.7.10
+		if(intendedVersionId() == "1.7.10")
+		{
+			auto insert = [&outLibs, &libraryNames](QString name)
+			{
+				QJsonObject libObj;
+				libObj.insert("insert", QString("replace"));
+				libObj.insert("name", name);
+				libraryNames.push_back(name);
+				outLibs.prepend(libObj);
+			};
+			insert("com.google.guava:guava:16.0");
+			insert("org.apache.commons:commons-lang3:3.2.1");
+		}
+		root.insert("+libraries", outLibs);
+		root.insert("order", 1);
+		root.insert("fileId", QString("org.multimc.ftb.pack.json"));
+		root.insert("name", name());
+		root.insert("mcVersion", intendedVersionId());
+		root.insert("version", intendedVersionId());
+		FS::ensureFilePathExists(newDir.absoluteFilePath("patches/ftb.json"));
+		QFile out(newDir.absoluteFilePath("patches/ftb.json"));
+		if (!out.open(QFile::WriteOnly | QFile::Truncate))
+		{
+			qCritical() << "Couldn't open" << out.fileName() << ":" << out.errorString();
+			return;
+		}
+		out.write(QJsonDocument(root).toJson());
+	}
+	// copy libraries
+	{
+		qDebug() << "Copying FTB libraries";
+		for (auto library : libraryNames)
+		{
+			GradleSpecifier lib(library);
+			const QString out = QDir::current().absoluteFilePath("libraries/" + lib.toPath());
+			if (QFile::exists(out))
+			{
+				continue;
+			}
+			if (!FS::ensureFilePathExists(out))
+			{
+				qCritical() << "Couldn't create folder structure for" << out;
+			}
+			if (!QFile::copy(librariesPath().absoluteFilePath(lib.toPath()), out))
+			{
+				qCritical() << "Couldn't copy" << QString(lib);
+			}
+		}
+	}
+	// now set the target instance to be plain OneSix
+	INISettingsObject settings_obj(newDir.absoluteFilePath("instance.cfg"));
+	settings_obj.registerSetting("InstanceType", "Legacy");
+	QString inst_type = settings_obj.get("InstanceType").toString();
+	settings_obj.set("InstanceType", "OneSix");
+}
+
+QString OneSixFTBInstance::id() const
+{
+	return "FTB/" + BaseInstance::id();
+}
+
+QDir OneSixFTBInstance::librariesPath() const
+{
+	return QDir(m_globalSettings->get("FTBRoot").toString() + "/libraries");
+}
+
+QDir OneSixFTBInstance::versionsPath() const
+{
+	return QDir(m_globalSettings->get("FTBRoot").toString() + "/versions");
+}
+
+bool OneSixFTBInstance::providesVersionFile() const
+{
+	return true;
+}
+
+void OneSixFTBInstance::createProfile()
+{
+	m_profile.reset(new MinecraftProfile(new FTBProfileStrategy(this)));
+}
+
+std::shared_ptr<Task> OneSixFTBInstance::createUpdateTask()
+{
+	return OneSixInstance::createUpdateTask();
+}
+
+QString OneSixFTBInstance::typeName() const
+{
+	return tr("OneSix FTB");
+}
+
+#include "OneSixFTBInstance.moc"
diff --git a/libraries/logic/minecraft/ftb/OneSixFTBInstance.h b/libraries/logic/minecraft/ftb/OneSixFTBInstance.h
new file mode 100644
index 00000000..e7f8f485
--- /dev/null
+++ b/libraries/logic/minecraft/ftb/OneSixFTBInstance.h
@@ -0,0 +1,30 @@
+#pragma once
+
+#include "minecraft/onesix/OneSixInstance.h"
+
+class OneSixFTBInstance : public OneSixInstance
+{
+	Q_OBJECT
+public:
+	explicit OneSixFTBInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+    virtual ~OneSixFTBInstance(){};
+
+	void copy(const QDir &newDir) override;
+
+	virtual void createProfile() override;
+
+	virtual std::shared_ptr<Task> createUpdateTask() override;
+
+	virtual QString id() const override;
+
+	QDir librariesPath() const override;
+	QDir versionsPath() const override;
+	bool providesVersionFile() const override;
+	virtual QString typeName() const override;
+	bool canExport() const override
+	{
+		return false;
+	}
+private:
+	SettingsObjectPtr m_globalSettings;
+};
diff --git a/libraries/logic/minecraft/legacy/LegacyInstance.cpp b/libraries/logic/minecraft/legacy/LegacyInstance.cpp
new file mode 100644
index 00000000..f8264f20
--- /dev/null
+++ b/libraries/logic/minecraft/legacy/LegacyInstance.cpp
@@ -0,0 +1,453 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QFileInfo>
+#include <QDir>
+#include <settings/Setting.h>
+
+#include "LegacyInstance.h"
+
+#include "minecraft/legacy/LegacyUpdate.h"
+#include "launch/LaunchTask.h"
+#include <launch/steps/LaunchMinecraft.h>
+#include <launch/steps/PostLaunchCommand.h>
+#include <launch/steps/ModMinecraftJar.h>
+#include <launch/steps/Update.h>
+#include <launch/steps/PreLaunchCommand.h>
+#include <launch/steps/TextPrint.h>
+#include <launch/steps/CheckJava.h>
+#include "minecraft/ModList.h"
+#include "minecraft/WorldList.h"
+#include <MMCZip.h>
+#include <FileSystem.h>
+
+LegacyInstance::LegacyInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir)
+	: MinecraftInstance(globalSettings, settings, rootDir)
+{
+	m_lwjglFolderSetting = globalSettings->getSetting("LWJGLDir");
+	settings->registerSetting("NeedsRebuild", true);
+	settings->registerSetting("ShouldUpdate", false);
+	settings->registerSetting("JarVersion", "Unknown");
+	settings->registerSetting("LwjglVersion", "2.9.0");
+	settings->registerSetting("IntendedJarVersion", "");
+	/*
+	 * custom base jar has no default. it is determined in code... see the accessor methods for
+	 *it
+	 *
+	 * for instances that DO NOT have the CustomBaseJar setting (legacy instances),
+	 * [.]minecraft/bin/mcbackup.jar is the default base jar
+	 */
+	settings->registerSetting("UseCustomBaseJar", true);
+	settings->registerSetting("CustomBaseJar", "");
+}
+
+QString LegacyInstance::baseJar() const
+{
+	bool customJar = m_settings->get("UseCustomBaseJar").toBool();
+	if (customJar)
+	{
+		return customBaseJar();
+	}
+	else
+		return defaultBaseJar();
+}
+
+QString LegacyInstance::customBaseJar() const
+{
+	QString value = m_settings->get("CustomBaseJar").toString();
+	if (value.isNull() || value.isEmpty())
+	{
+		return defaultCustomBaseJar();
+	}
+	return value;
+}
+
+void LegacyInstance::setCustomBaseJar(QString val)
+{
+	if (val.isNull() || val.isEmpty() || val == defaultCustomBaseJar())
+		m_settings->reset("CustomBaseJar");
+	else
+		m_settings->set("CustomBaseJar", val);
+}
+
+void LegacyInstance::setShouldUseCustomBaseJar(bool val)
+{
+	m_settings->set("UseCustomBaseJar", val);
+}
+
+bool LegacyInstance::shouldUseCustomBaseJar() const
+{
+	return m_settings->get("UseCustomBaseJar").toBool();
+}
+
+
+std::shared_ptr<Task> LegacyInstance::createUpdateTask()
+{
+	// make sure the jar mods list is initialized by asking for it.
+	auto list = jarModList();
+	// create an update task
+	return std::shared_ptr<Task>(new LegacyUpdate(this, this));
+}
+
+std::shared_ptr<LaunchTask> LegacyInstance::createLaunchTask(AuthSessionPtr session)
+{
+	auto process = LaunchTask::create(std::dynamic_pointer_cast<MinecraftInstance>(getSharedPtr()));
+	auto pptr = process.get();
+
+	// print a header
+	{
+		process->appendStep(std::make_shared<TextPrint>(pptr, "Minecraft folder is:\n" + minecraftRoot() + "\n\n", MessageLevel::MultiMC));
+	}
+	{
+		auto step = std::make_shared<CheckJava>(pptr);
+		process->appendStep(step);
+	}
+	// run pre-launch command if that's needed
+	if(getPreLaunchCommand().size())
+	{
+		auto step = std::make_shared<PreLaunchCommand>(pptr);
+		step->setWorkingDirectory(minecraftRoot());
+		process->appendStep(step);
+	}
+	// if we aren't in offline mode,.
+	if(session->status != AuthSession::PlayableOffline)
+	{
+		process->appendStep(std::make_shared<Update>(pptr));
+	}
+	// if there are any jar mods
+	if(getJarMods().size())
+	{
+		auto step = std::make_shared<ModMinecraftJar>(pptr);
+		process->appendStep(step);
+	}
+	// actually launch the game
+	{
+		auto step = std::make_shared<LaunchMinecraft>(pptr);
+		step->setWorkingDirectory(minecraftRoot());
+		step->setAuthSession(session);
+		process->appendStep(step);
+	}
+	// run post-exit command if that's needed
+	if(getPostExitCommand().size())
+	{
+		auto step = std::make_shared<PostLaunchCommand>(pptr);
+		step->setWorkingDirectory(minecraftRoot());
+		process->appendStep(step);
+	}
+	if (session)
+	{
+		process->setCensorFilter(createCensorFilterFromSession(session));
+	}
+	return process;
+}
+
+std::shared_ptr<Task> LegacyInstance::createJarModdingTask()
+{
+	class JarModTask : public Task
+	{
+	public:
+		explicit JarModTask(std::shared_ptr<LegacyInstance> inst) : Task(nullptr), m_inst(inst)
+		{
+		}
+		virtual void executeTask()
+		{
+			if (!m_inst->shouldRebuild())
+			{
+				emitSucceeded();
+				return;
+			}
+
+			// Get the mod list
+			auto modList = m_inst->getJarMods();
+
+			QFileInfo runnableJar(m_inst->runnableJar());
+			QFileInfo baseJar(m_inst->baseJar());
+			bool base_is_custom = m_inst->shouldUseCustomBaseJar();
+
+			// Nothing to do if there are no jar mods to install, no backup and just the mc jar
+			if (base_is_custom)
+			{
+				// yes, this can happen if the instance only has the runnable jar and not the base jar
+				// it *could* be assumed that such an instance is vanilla, but that wouldn't be safe
+				// because that's not something mmc4 guarantees
+				if (runnableJar.isFile() && !baseJar.exists() && modList.empty())
+				{
+					m_inst->setShouldRebuild(false);
+					emitSucceeded();
+					return;
+				}
+
+				setStatus(tr("Installing mods: Backing up minecraft.jar ..."));
+				if (!baseJar.exists() && !QFile::copy(runnableJar.filePath(), baseJar.filePath()))
+				{
+					emitFailed("It seems both the active and base jar are gone. A fresh base jar will "
+							"be used on next run.");
+					m_inst->setShouldRebuild(true);
+					m_inst->setShouldUpdate(true);
+					m_inst->setShouldUseCustomBaseJar(false);
+					return;
+				}
+			}
+
+			if (!baseJar.exists())
+			{
+				emitFailed("The base jar " + baseJar.filePath() + " does not exist");
+				return;
+			}
+
+			if (runnableJar.exists() && !QFile::remove(runnableJar.filePath()))
+			{
+				emitFailed("Failed to delete old minecraft.jar");
+				return;
+			}
+
+			setStatus(tr("Installing mods: Opening minecraft.jar ..."));
+
+			QString outputJarPath = runnableJar.filePath();
+			QString inputJarPath = baseJar.filePath();
+
+			if(!MMCZip::createModdedJar(inputJarPath, outputJarPath, modList))
+			{
+				emitFailed(tr("Failed to create the custom Minecraft jar file."));
+				return;
+			}
+			m_inst->setShouldRebuild(false);
+			// inst->UpdateVersion(true);
+			emitSucceeded();
+			return;
+
+		}
+		std::shared_ptr<LegacyInstance> m_inst;
+	};
+	return std::make_shared<JarModTask>(std::dynamic_pointer_cast<LegacyInstance>(shared_from_this()));
+}
+
+QString LegacyInstance::createLaunchScript(AuthSessionPtr session)
+{
+	QString launchScript;
+
+	// window size
+	QString windowParams;
+	if (settings()->get("LaunchMaximized").toBool())
+	{
+		windowParams = "max";
+	}
+	else
+	{
+		windowParams = QString("%1x%2").arg(settings()->get("MinecraftWinWidth").toInt()).arg(settings()->get("MinecraftWinHeight").toInt());
+	}
+
+	QString lwjgl = QDir(m_lwjglFolderSetting->get().toString() + "/" + lwjglVersion()).absolutePath();
+	launchScript += "userName " + session->player_name + "\n";
+	launchScript += "sessionId " + session->session + "\n";
+	launchScript += "windowTitle " + windowTitle() + "\n";
+	launchScript += "windowParams " + windowParams + "\n";
+	launchScript += "lwjgl " + lwjgl + "\n";
+	launchScript += "launcher legacy\n";
+	return launchScript;
+}
+
+void LegacyInstance::cleanupAfterRun()
+{
+	// FIXME: delete the launcher and icons and whatnot.
+}
+
+std::shared_ptr<ModList> LegacyInstance::coreModList() const
+{
+	if (!core_mod_list)
+	{
+		core_mod_list.reset(new ModList(coreModsDir()));
+	}
+	core_mod_list->update();
+	return core_mod_list;
+}
+
+std::shared_ptr<ModList> LegacyInstance::jarModList() const
+{
+	if (!jar_mod_list)
+	{
+		auto list = new ModList(jarModsDir(), modListFile());
+		connect(list, SIGNAL(changed()), SLOT(jarModsChanged()));
+		jar_mod_list.reset(list);
+	}
+	jar_mod_list->update();
+	return jar_mod_list;
+}
+
+QList<Mod> LegacyInstance::getJarMods() const
+{
+	return jarModList()->allMods();
+}
+
+void LegacyInstance::jarModsChanged()
+{
+	qDebug() << "Jar mods of instance " << name() << " have changed. Jar will be rebuilt.";
+	setShouldRebuild(true);
+}
+
+std::shared_ptr<ModList> LegacyInstance::loaderModList() const
+{
+	if (!loader_mod_list)
+	{
+		loader_mod_list.reset(new ModList(loaderModsDir()));
+	}
+	loader_mod_list->update();
+	return loader_mod_list;
+}
+
+std::shared_ptr<ModList> LegacyInstance::texturePackList() const
+{
+	if (!texture_pack_list)
+	{
+		texture_pack_list.reset(new ModList(texturePacksDir()));
+	}
+	texture_pack_list->update();
+	return texture_pack_list;
+}
+
+std::shared_ptr<WorldList> LegacyInstance::worldList() const
+{
+	if (!m_world_list)
+	{
+		m_world_list.reset(new WorldList(savesDir()));
+	}
+	return m_world_list;
+}
+
+QString LegacyInstance::jarModsDir() const
+{
+	return FS::PathCombine(instanceRoot(), "instMods");
+}
+
+QString LegacyInstance::binDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "bin");
+}
+
+QString LegacyInstance::libDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "lib");
+}
+
+QString LegacyInstance::savesDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "saves");
+}
+
+QString LegacyInstance::loaderModsDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "mods");
+}
+
+QString LegacyInstance::coreModsDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "coremods");
+}
+
+QString LegacyInstance::resourceDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "resources");
+}
+QString LegacyInstance::texturePacksDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "texturepacks");
+}
+
+QString LegacyInstance::runnableJar() const
+{
+	return FS::PathCombine(binDir(), "minecraft.jar");
+}
+
+QString LegacyInstance::modListFile() const
+{
+	return FS::PathCombine(instanceRoot(), "modlist");
+}
+
+QString LegacyInstance::instanceConfigFolder() const
+{
+	return FS::PathCombine(minecraftRoot(), "config");
+}
+
+bool LegacyInstance::shouldRebuild() const
+{
+	return m_settings->get("NeedsRebuild").toBool();
+}
+
+void LegacyInstance::setShouldRebuild(bool val)
+{
+	m_settings->set("NeedsRebuild", val);
+}
+
+QString LegacyInstance::currentVersionId() const
+{
+	return m_settings->get("JarVersion").toString();
+}
+
+QString LegacyInstance::lwjglVersion() const
+{
+	return m_settings->get("LwjglVersion").toString();
+}
+
+void LegacyInstance::setLWJGLVersion(QString val)
+{
+	m_settings->set("LwjglVersion", val);
+}
+
+QString LegacyInstance::intendedVersionId() const
+{
+	return m_settings->get("IntendedJarVersion").toString();
+}
+
+bool LegacyInstance::setIntendedVersionId(QString version)
+{
+	settings()->set("IntendedJarVersion", version);
+	setShouldUpdate(true);
+	return true;
+}
+
+bool LegacyInstance::shouldUpdate() const
+{
+	QVariant var = settings()->get("ShouldUpdate");
+	if (!var.isValid() || var.toBool() == false)
+	{
+		return intendedVersionId() != currentVersionId();
+	}
+	return true;
+}
+
+void LegacyInstance::setShouldUpdate(bool val)
+{
+	settings()->set("ShouldUpdate", val);
+}
+
+QString LegacyInstance::defaultBaseJar() const
+{
+	return "versions/" + intendedVersionId() + "/" + intendedVersionId() + ".jar";
+}
+
+QString LegacyInstance::defaultCustomBaseJar() const
+{
+	return FS::PathCombine(binDir(), "mcbackup.jar");
+}
+
+QString LegacyInstance::lwjglFolder() const
+{
+	return m_lwjglFolderSetting->get().toString();
+}
+
+QString LegacyInstance::typeName() const
+{
+	return tr("Legacy");
+}
diff --git a/libraries/logic/minecraft/legacy/LegacyInstance.h b/libraries/logic/minecraft/legacy/LegacyInstance.h
new file mode 100644
index 00000000..3bef240d
--- /dev/null
+++ b/libraries/logic/minecraft/legacy/LegacyInstance.h
@@ -0,0 +1,142 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "minecraft/MinecraftInstance.h"
+
+#include "multimc_logic_export.h"
+
+class ModList;
+class Task;
+
+class MULTIMC_LOGIC_EXPORT LegacyInstance : public MinecraftInstance
+{
+	Q_OBJECT
+public:
+
+	explicit LegacyInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+
+	virtual void init() override {};
+
+	/// Path to the instance's minecraft.jar
+	QString runnableJar() const;
+
+	//! Path to the instance's modlist file.
+	QString modListFile() const;
+
+	/*
+	////// Edit Instance Dialog stuff //////
+	virtual QList<BasePage *> getPages();
+	virtual QString dialogTitle();
+	*/
+
+	//////  Mod Lists  //////
+	std::shared_ptr<ModList> jarModList() const ;
+	virtual QList< Mod > getJarMods() const override;
+	std::shared_ptr<ModList> coreModList() const;
+	std::shared_ptr<ModList> loaderModList() const;
+	std::shared_ptr<ModList> texturePackList() const override;
+	std::shared_ptr<WorldList> worldList() const override;
+
+	////// Directories //////
+	QString libDir() const;
+	QString savesDir() const;
+	QString texturePacksDir() const;
+	QString jarModsDir() const;
+	QString binDir() const;
+	QString loaderModsDir() const;
+	QString coreModsDir() const;
+	QString resourceDir() const;
+	virtual QString instanceConfigFolder() const override;
+
+		/// Get the curent base jar of this instance. By default, it's the
+	/// versions/$version/$version.jar
+	QString baseJar() const;
+
+	/// the default base jar of this instance
+	QString defaultBaseJar() const;
+	/// the default custom base jar of this instance
+	QString defaultCustomBaseJar() const;
+
+	/*!
+	 * Whether or not custom base jar is used
+	 */
+	bool shouldUseCustomBaseJar() const;
+	void setShouldUseCustomBaseJar(bool val);
+
+	/*!
+	 * The value of the custom base jar
+	 */
+	QString customBaseJar() const;
+	void setCustomBaseJar(QString val);
+
+	/*!
+	 * Whether or not the instance's minecraft.jar needs to be rebuilt.
+	 * If this is true, when the instance launches, its jar mods will be
+	 * re-added to a fresh minecraft.jar file.
+	 */
+	bool shouldRebuild() const;
+	void setShouldRebuild(bool val);
+
+	virtual QString currentVersionId() const override;
+
+	//! The version of LWJGL that this instance uses.
+	QString lwjglVersion() const;
+
+	//! Where the lwjgl versions foor this instance can be found... HACK HACK HACK
+	QString lwjglFolder() const;
+
+	/// st the version of LWJGL libs this instance will use
+	void setLWJGLVersion(QString val);
+
+	virtual QString intendedVersionId() const override;
+	virtual bool setIntendedVersionId(QString version) override;
+
+	virtual QSet<QString> traits() override
+	{
+		return {"legacy-instance", "texturepacks"};
+	};
+
+	virtual bool shouldUpdate() const override;
+	virtual void setShouldUpdate(bool val) override;
+	virtual std::shared_ptr<Task> createUpdateTask() override;
+
+	virtual std::shared_ptr<LaunchTask> createLaunchTask(AuthSessionPtr account) override;
+
+	virtual std::shared_ptr<Task> createJarModdingTask() override;
+
+	virtual QString createLaunchScript(AuthSessionPtr session) override;
+
+	virtual void cleanupAfterRun() override;
+
+	virtual QString typeName() const override;
+
+	bool canExport() const override
+	{
+		return true;
+	}
+
+protected:
+	mutable std::shared_ptr<ModList> jar_mod_list;
+	mutable std::shared_ptr<ModList> core_mod_list;
+	mutable std::shared_ptr<ModList> loader_mod_list;
+	mutable std::shared_ptr<ModList> texture_pack_list;
+	mutable std::shared_ptr<WorldList> m_world_list;
+	std::shared_ptr<Setting> m_lwjglFolderSetting;
+protected
+slots:
+	virtual void jarModsChanged();
+};
diff --git a/libraries/logic/minecraft/legacy/LegacyUpdate.cpp b/libraries/logic/minecraft/legacy/LegacyUpdate.cpp
new file mode 100644
index 00000000..2d7e8dd2
--- /dev/null
+++ b/libraries/logic/minecraft/legacy/LegacyUpdate.cpp
@@ -0,0 +1,393 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QStringList>
+#include <quazip.h>
+#include <quazipfile.h>
+#include <QDebug>
+
+#include "Env.h"
+#include "BaseInstance.h"
+#include "net/URLConstants.h"
+#include "MMCZip.h"
+
+#include "LegacyUpdate.h"
+
+#include "LwjglVersionList.h"
+#include "minecraft/MinecraftVersionList.h"
+#include "minecraft/ModList.h"
+#include "LegacyInstance.h"
+#include <FileSystem.h>
+
+LegacyUpdate::LegacyUpdate(BaseInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
+{
+}
+
+void LegacyUpdate::executeTask()
+{
+	fmllibsStart();
+}
+
+void LegacyUpdate::fmllibsStart()
+{
+	// Get the mod list
+	LegacyInstance *inst = (LegacyInstance *)m_inst;
+	auto modList = inst->jarModList();
+
+	bool forge_present = false;
+
+	QString version = inst->intendedVersionId();
+	auto & fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
+	if (!fmlLibsMapping.contains(version))
+	{
+		lwjglStart();
+		return;
+	}
+
+	auto &libList = fmlLibsMapping[version];
+
+	// determine if we need some libs for FML or forge
+	setStatus(tr("Checking for FML libraries..."));
+	for (unsigned i = 0; i < modList->size(); i++)
+	{
+		auto &mod = modList->operator[](i);
+
+		// do not use disabled mods.
+		if (!mod.enabled())
+			continue;
+
+		if (mod.type() != Mod::MOD_ZIPFILE)
+			continue;
+
+		if (mod.mmc_id().contains("forge", Qt::CaseInsensitive))
+		{
+			forge_present = true;
+			break;
+		}
+		if (mod.mmc_id().contains("fml", Qt::CaseInsensitive))
+		{
+			forge_present = true;
+			break;
+		}
+	}
+	// we don't...
+	if (!forge_present)
+	{
+		lwjglStart();
+		return;
+	}
+
+	// now check the lib folder inside the instance for files.
+	for (auto &lib : libList)
+	{
+		QFileInfo libInfo(FS::PathCombine(inst->libDir(), lib.filename));
+		if (libInfo.exists())
+			continue;
+		fmlLibsToProcess.append(lib);
+	}
+
+	// if everything is in place, there's nothing to do here...
+	if (fmlLibsToProcess.isEmpty())
+	{
+		lwjglStart();
+		return;
+	}
+
+	// download missing libs to our place
+	setStatus(tr("Dowloading FML libraries..."));
+	auto dljob = new NetJob("FML libraries");
+	auto metacache = ENV.metacache();
+	for (auto &lib : fmlLibsToProcess)
+	{
+		auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+		QString urlString = lib.ours ? URLConstants::FMLLIBS_OUR_BASE_URL + lib.filename
+									 : URLConstants::FMLLIBS_FORGE_BASE_URL + lib.filename;
+		dljob->addNetAction(CacheDownload::make(QUrl(urlString), entry));
+	}
+
+	connect(dljob, &NetJob::succeeded, this, &LegacyUpdate::fmllibsFinished);
+	connect(dljob, &NetJob::failed, this, &LegacyUpdate::fmllibsFailed);
+	connect(dljob, &NetJob::progress, this, &LegacyUpdate::progress);
+	legacyDownloadJob.reset(dljob);
+	legacyDownloadJob->start();
+}
+
+void LegacyUpdate::fmllibsFinished()
+{
+	legacyDownloadJob.reset();
+	if(!fmlLibsToProcess.isEmpty())
+	{
+		setStatus(tr("Copying FML libraries into the instance..."));
+		LegacyInstance *inst = (LegacyInstance *)m_inst;
+		auto metacache = ENV.metacache();
+		int index = 0;
+		for (auto &lib : fmlLibsToProcess)
+		{
+			progress(index, fmlLibsToProcess.size());
+			auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+			auto path = FS::PathCombine(inst->libDir(), lib.filename);
+			if(!FS::ensureFilePathExists(path))
+			{
+				emitFailed(tr("Failed creating FML library folder inside the instance."));
+				return;
+			}
+			if (!QFile::copy(entry->getFullPath(), FS::PathCombine(inst->libDir(), lib.filename)))
+			{
+				emitFailed(tr("Failed copying Forge/FML library: %1.").arg(lib.filename));
+				return;
+			}
+			index++;
+		}
+		progress(index, fmlLibsToProcess.size());
+	}
+	lwjglStart();
+}
+
+void LegacyUpdate::fmllibsFailed(QString reason)
+{
+	emitFailed(tr("Game update failed: it was impossible to fetch the required FML libraries. Reason: %1").arg(reason));
+	return;
+}
+
+void LegacyUpdate::lwjglStart()
+{
+	LegacyInstance *inst = (LegacyInstance *)m_inst;
+
+	lwjglVersion = inst->lwjglVersion();
+	lwjglTargetPath = FS::PathCombine(inst->lwjglFolder(), lwjglVersion);
+	lwjglNativesPath = FS::PathCombine(lwjglTargetPath, "natives");
+
+	// if the 'done' file exists, we don't have to download this again
+	QFileInfo doneFile(FS::PathCombine(lwjglTargetPath, "done"));
+	if (doneFile.exists())
+	{
+		jarStart();
+		return;
+	}
+
+	auto list = std::dynamic_pointer_cast<LWJGLVersionList>(ENV.getVersionList("org.lwjgl.legacy"));
+	if (!list->isLoaded())
+	{
+		emitFailed("Too soon! Let the LWJGL list load :)");
+		return;
+	}
+
+	setStatus(tr("Downloading new LWJGL..."));
+	auto version = std::dynamic_pointer_cast<LWJGLVersion>(list->findVersion(lwjglVersion));
+	if (!version)
+	{
+		emitFailed("Game update failed: the selected LWJGL version is invalid.");
+		return;
+	}
+
+	QString url = version->url();
+	QUrl realUrl(url);
+	QString hostname = realUrl.host();
+	auto worker = ENV.qnam();
+	QNetworkRequest req(realUrl);
+	req.setRawHeader("Host", hostname.toLatin1());
+	req.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Cached)");
+	QNetworkReply *rep = worker->get(req);
+
+	m_reply = std::shared_ptr<QNetworkReply>(rep);
+	connect(rep, &QNetworkReply::downloadProgress, this, &LegacyUpdate::progress);
+	connect(worker.get(), &QNetworkAccessManager::finished, this, &LegacyUpdate::lwjglFinished);
+}
+
+void LegacyUpdate::lwjglFinished(QNetworkReply *reply)
+{
+	if (m_reply.get() != reply)
+	{
+		return;
+	}
+	if (reply->error() != QNetworkReply::NoError)
+	{
+		emitFailed("Failed to download: " + reply->errorString() +
+				   "\nSometimes you have to wait a bit if you download many LWJGL versions in "
+				   "a row. YMMV");
+		return;
+	}
+	auto worker = ENV.qnam();
+	// Here i check if there is a cookie for me in the reply and extract it
+	QList<QNetworkCookie> cookies =
+		qvariant_cast<QList<QNetworkCookie>>(reply->header(QNetworkRequest::SetCookieHeader));
+	if (cookies.count() != 0)
+	{
+		// you must tell which cookie goes with which url
+		worker->cookieJar()->setCookiesFromUrl(cookies, QUrl("sourceforge.net"));
+	}
+
+	// here you can check for the 302 or whatever other header i need
+	QVariant newLoc = reply->header(QNetworkRequest::LocationHeader);
+	if (newLoc.isValid())
+	{
+		QString redirectedTo = reply->header(QNetworkRequest::LocationHeader).toString();
+		QUrl realUrl(redirectedTo);
+		QString hostname = realUrl.host();
+		QNetworkRequest req(redirectedTo);
+		req.setRawHeader("Host", hostname.toLatin1());
+		req.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Cached)");
+		QNetworkReply *rep = worker->get(req);
+		connect(rep, &QNetworkReply::downloadProgress, this, &LegacyUpdate::progress);
+		m_reply = std::shared_ptr<QNetworkReply>(rep);
+		return;
+	}
+	QFile saveMe("lwjgl.zip");
+	saveMe.open(QIODevice::WriteOnly);
+	saveMe.write(m_reply->readAll());
+	saveMe.close();
+	setStatus(tr("Installing new LWJGL..."));
+	extractLwjgl();
+	jarStart();
+}
+void LegacyUpdate::extractLwjgl()
+{
+	// make sure the directories are there
+
+	bool success = FS::ensureFolderPathExists(lwjglNativesPath);
+
+	if (!success)
+	{
+		emitFailed("Failed to extract the lwjgl libs - error when creating required folders.");
+		return;
+	}
+
+	QuaZip zip("lwjgl.zip");
+	if (!zip.open(QuaZip::mdUnzip))
+	{
+		emitFailed("Failed to extract the lwjgl libs - not a valid archive.");
+		return;
+	}
+
+	// and now we are going to access files inside it
+	QuaZipFile file(&zip);
+	const QString jarNames[] = {"jinput.jar", "lwjgl_util.jar", "lwjgl.jar"};
+	for (bool more = zip.goToFirstFile(); more; more = zip.goToNextFile())
+	{
+		if (!file.open(QIODevice::ReadOnly))
+		{
+			zip.close();
+			emitFailed("Failed to extract the lwjgl libs - error while reading archive.");
+			return;
+		}
+		QuaZipFileInfo info;
+		QString name = file.getActualFileName();
+		if (name.endsWith('/'))
+		{
+			file.close();
+			continue;
+		}
+		QString destFileName;
+		// Look for the jars
+		for (int i = 0; i < 3; i++)
+		{
+			if (name.endsWith(jarNames[i]))
+			{
+				destFileName = FS::PathCombine(lwjglTargetPath, jarNames[i]);
+			}
+		}
+		// Not found? look for the natives
+		if (destFileName.isEmpty())
+		{
+#ifdef Q_OS_WIN32
+			QString nativesDir = "windows";
+#else
+#ifdef Q_OS_MAC
+			QString nativesDir = "macosx";
+#else
+			QString nativesDir = "linux";
+#endif
+#endif
+			if (name.contains(nativesDir))
+			{
+				int lastSlash = name.lastIndexOf('/');
+				int lastBackSlash = name.lastIndexOf('\\');
+				if (lastSlash != -1)
+					name = name.mid(lastSlash + 1);
+				else if (lastBackSlash != -1)
+					name = name.mid(lastBackSlash + 1);
+				destFileName = FS::PathCombine(lwjglNativesPath, name);
+			}
+		}
+		// Now if destFileName is still empty, go to the next file.
+		if (!destFileName.isEmpty())
+		{
+			setStatus(tr("Installing new LWJGL - extracting ") + name + "...");
+			QFile output(destFileName);
+			output.open(QIODevice::WriteOnly);
+			output.write(file.readAll());
+			output.close();
+		}
+		file.close(); // do not forget to close!
+	}
+	zip.close();
+	m_reply.reset();
+	QFile doneFile(FS::PathCombine(lwjglTargetPath, "done"));
+	doneFile.open(QIODevice::WriteOnly);
+	doneFile.write("done.");
+	doneFile.close();
+}
+
+void LegacyUpdate::lwjglFailed(QString reason)
+{
+	emitFailed(tr("Bad stuff happened while trying to get the lwjgl libs: %1").arg(reason));
+}
+
+void LegacyUpdate::jarStart()
+{
+	LegacyInstance *inst = (LegacyInstance *)m_inst;
+	if (!inst->shouldUpdate() || inst->shouldUseCustomBaseJar())
+	{
+		emitSucceeded();
+		return;
+	}
+
+	setStatus(tr("Checking for jar updates..."));
+	// Make directories
+	QDir binDir(inst->binDir());
+	if (!binDir.exists() && !binDir.mkpath("."))
+	{
+		emitFailed("Failed to create bin folder.");
+		return;
+	}
+
+	// Build a list of URLs that will need to be downloaded.
+	setStatus(tr("Downloading new minecraft.jar ..."));
+
+	QString version_id = inst->intendedVersionId();
+
+	auto dljob = new NetJob("Minecraft.jar for version " + version_id);
+
+	auto metacache = ENV.metacache();
+	auto entry = metacache->resolveEntry("versions", URLConstants::getJarPath(version_id));
+	dljob->addNetAction(CacheDownload::make(QUrl(URLConstants::getLegacyJarUrl(version_id)), entry));
+	connect(dljob, SIGNAL(succeeded()), SLOT(jarFinished()));
+	connect(dljob, SIGNAL(failed(QString)), SLOT(jarFailed(QString)));
+	connect(dljob, SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	legacyDownloadJob.reset(dljob);
+	legacyDownloadJob->start();
+}
+
+void LegacyUpdate::jarFinished()
+{
+	// process the jar
+	emitSucceeded();
+}
+
+void LegacyUpdate::jarFailed(QString reason)
+{
+	// bad, bad
+	emitFailed(tr("Failed to download the minecraft jar: %1.").arg(reason));
+}
diff --git a/libraries/logic/minecraft/legacy/LegacyUpdate.h b/libraries/logic/minecraft/legacy/LegacyUpdate.h
new file mode 100644
index 00000000..c52bf934
--- /dev/null
+++ b/libraries/logic/minecraft/legacy/LegacyUpdate.h
@@ -0,0 +1,70 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QList>
+#include <QUrl>
+
+#include "net/NetJob.h"
+#include "tasks/Task.h"
+#include "minecraft/VersionFilterData.h"
+
+class MinecraftVersion;
+class BaseInstance;
+class QuaZip;
+class Mod;
+
+class LegacyUpdate : public Task
+{
+	Q_OBJECT
+public:
+	explicit LegacyUpdate(BaseInstance *inst, QObject *parent = 0);
+	virtual void executeTask();
+
+private
+slots:
+	void lwjglStart();
+	void lwjglFinished(QNetworkReply *);
+	void lwjglFailed(QString reason);
+
+	void jarStart();
+	void jarFinished();
+	void jarFailed(QString reason);
+
+	void fmllibsStart();
+	void fmllibsFinished();
+	void fmllibsFailed(QString reason);
+
+	void extractLwjgl();
+
+private:
+
+	std::shared_ptr<QNetworkReply> m_reply;
+
+	// target version, determined during this task
+	// MinecraftVersion *targetVersion;
+	QString lwjglURL;
+	QString lwjglVersion;
+
+	QString lwjglTargetPath;
+	QString lwjglNativesPath;
+
+private:
+	NetJobPtr legacyDownloadJob;
+	BaseInstance *m_inst = nullptr;
+	QList<FMLlib> fmlLibsToProcess;
+};
diff --git a/libraries/logic/minecraft/legacy/LwjglVersionList.cpp b/libraries/logic/minecraft/legacy/LwjglVersionList.cpp
new file mode 100644
index 00000000..bb017368
--- /dev/null
+++ b/libraries/logic/minecraft/legacy/LwjglVersionList.cpp
@@ -0,0 +1,189 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LwjglVersionList.h"
+#include "Env.h"
+
+#include <QtNetwork>
+#include <QtXml>
+#include <QRegExp>
+
+#include <QDebug>
+
+#define RSS_URL "http://sourceforge.net/projects/java-game-lib/rss"
+
+LWJGLVersionList::LWJGLVersionList(QObject *parent) : BaseVersionList(parent)
+{
+	setLoading(false);
+}
+
+QVariant LWJGLVersionList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	const PtrLWJGLVersion version = m_vlist.at(index.row());
+
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		return version->name();
+
+	case Qt::ToolTipRole:
+		return version->url();
+
+	default:
+		return QVariant();
+	}
+}
+
+QVariant LWJGLVersionList::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		return tr("Version");
+
+	case Qt::ToolTipRole:
+		return tr("LWJGL version name.");
+
+	default:
+		return QVariant();
+	}
+}
+
+int LWJGLVersionList::columnCount(const QModelIndex &parent) const
+{
+	return 1;
+}
+
+bool LWJGLVersionList::isLoading() const
+{
+	return m_loading;
+}
+
+void LWJGLVersionList::loadList()
+{
+	Q_ASSERT_X(!m_loading, "loadList", "list is already loading (m_loading is true)");
+
+	setLoading(true);
+	auto worker = ENV.qnam();
+	QNetworkRequest req(QUrl(RSS_URL));
+	req.setRawHeader("Accept", "application/rss+xml, text/xml, */*");
+	req.setRawHeader("User-Agent", "MultiMC/5.0 (Uncached)");
+	reply = worker->get(req);
+	connect(reply, SIGNAL(finished()), SLOT(netRequestComplete()));
+}
+
+inline QDomElement getDomElementByTagName(QDomElement parent, QString tagname)
+{
+	QDomNodeList elementList = parent.elementsByTagName(tagname);
+	if (elementList.count())
+		return elementList.at(0).toElement();
+	else
+		return QDomElement();
+}
+
+void LWJGLVersionList::netRequestComplete()
+{
+	if (reply->error() == QNetworkReply::NoError)
+	{
+		QRegExp lwjglRegex("lwjgl-(([0-9]\\.?)+)\\.zip");
+		Q_ASSERT_X(lwjglRegex.isValid(), "load LWJGL list", "LWJGL regex is invalid");
+
+		QDomDocument doc;
+
+		QString xmlErrorMsg;
+		int errorLine;
+		auto rawData = reply->readAll();
+		if (!doc.setContent(rawData, false, &xmlErrorMsg, &errorLine))
+		{
+			failed("Failed to load LWJGL list. XML error: " + xmlErrorMsg + " at line " +
+				   QString::number(errorLine));
+			setLoading(false);
+			return;
+		}
+
+		QDomNodeList items = doc.elementsByTagName("item");
+
+		QList<PtrLWJGLVersion> tempList;
+
+		for (int i = 0; i < items.length(); i++)
+		{
+			Q_ASSERT_X(items.at(i).isElement(), "load LWJGL list",
+					   "XML element isn't an element... wat?");
+
+			QDomElement linkElement = getDomElementByTagName(items.at(i).toElement(), "link");
+			if (linkElement.isNull())
+			{
+				qDebug() << "Link element" << i << "in RSS feed doesn't exist! Skipping.";
+				continue;
+			}
+
+			QString link = linkElement.text();
+
+			// Make sure it's a download link.
+			if (link.endsWith("/download") && link.contains(lwjglRegex))
+			{
+				QString name = link.mid(lwjglRegex.indexIn(link) + 6);
+				// Subtract 4 here to remove the .zip file extension.
+				name = name.left(lwjglRegex.matchedLength() - 10);
+
+				QUrl url(link);
+				if (!url.isValid())
+				{
+					qWarning() << "LWJGL version URL isn't valid:" << link << "Skipping.";
+					continue;
+				}
+				qDebug() << "Discovered LWGL version" << name << "at" << link;
+				tempList.append(std::make_shared<LWJGLVersion>(name, link));
+			}
+		}
+
+		beginResetModel();
+		m_vlist.swap(tempList);
+		endResetModel();
+
+		qDebug() << "Loaded LWJGL list.";
+		finished();
+	}
+	else
+	{
+		failed("Failed to load LWJGL list. Network error: " + reply->errorString());
+	}
+
+	setLoading(false);
+	reply->deleteLater();
+}
+
+void LWJGLVersionList::failed(QString msg)
+{
+	qCritical() << msg;
+	emit loadListFailed(msg);
+}
+
+void LWJGLVersionList::finished()
+{
+	emit loadListFinished();
+}
+
+void LWJGLVersionList::setLoading(bool loading)
+{
+	m_loading = loading;
+	emit loadingStateUpdated(m_loading);
+}
diff --git a/libraries/logic/minecraft/legacy/LwjglVersionList.h b/libraries/logic/minecraft/legacy/LwjglVersionList.h
new file mode 100644
index 00000000..f043f6e2
--- /dev/null
+++ b/libraries/logic/minecraft/legacy/LwjglVersionList.h
@@ -0,0 +1,156 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QAbstractListModel>
+#include <QUrl>
+#include <QNetworkReply>
+#include <memory>
+
+#include "BaseVersion.h"
+#include "BaseVersionList.h"
+
+#include "multimc_logic_export.h"
+
+class LWJGLVersion;
+typedef std::shared_ptr<LWJGLVersion> PtrLWJGLVersion;
+
+class MULTIMC_LOGIC_EXPORT LWJGLVersion : public BaseVersion
+{
+public:
+	LWJGLVersion(const QString &name, const QString &url)
+		: m_name(name), m_url(url)
+	{
+	}
+
+	virtual QString descriptor()
+	{
+		return m_name;
+	}
+
+	virtual QString name()
+	{
+		return m_name;
+	}
+
+	virtual QString typeString() const
+	{
+		return QObject::tr("Upstream");
+	}
+
+	QString url() const
+	{
+		return m_url;
+	}
+
+protected:
+	QString m_name;
+	QString m_url;
+};
+
+class MULTIMC_LOGIC_EXPORT LWJGLVersionList : public BaseVersionList
+{
+	Q_OBJECT
+public:
+	explicit LWJGLVersionList(QObject *parent = 0);
+
+	bool isLoaded() override
+	{
+		return m_vlist.length() > 0;
+	}
+	virtual const BaseVersionPtr at(int i) const override
+	{
+		return m_vlist[i];
+	}
+
+	virtual Task* getLoadTask() override
+	{
+		return nullptr;
+	}
+
+	virtual void sortVersions() override {};
+
+	virtual void updateListData(QList< BaseVersionPtr > versions) override {};
+
+	int count() const override
+	{
+		return m_vlist.length();
+	}
+
+	virtual QVariant data(const QModelIndex &index, int role) const override;
+	virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+	virtual int rowCount(const QModelIndex &parent) const override
+	{
+		return count();
+	}
+	virtual int columnCount(const QModelIndex &parent) const override;
+
+	virtual bool isLoading() const;
+	virtual bool errored() const
+	{
+		return m_errored;
+	}
+
+	virtual QString lastErrorMsg() const
+	{
+		return m_lastErrorMsg;
+	}
+
+public
+slots:
+	/*!
+	 * Loads the version list.
+	 * This is done asynchronously. On success, the loadListFinished() signal will
+	 * be emitted. The list model will be reset as well, resulting in the modelReset()
+	 * signal being emitted. Note that the model will be reset before loadListFinished() is
+	 * emitted.
+	 * If loading the list failed, the loadListFailed(QString msg),
+	 * signal will be emitted.
+	 */
+	virtual void loadList();
+
+signals:
+	/*!
+	 * Emitted when the list either starts or finishes loading.
+	 * \param loading Whether or not the list is loading.
+	 */
+	void loadingStateUpdated(bool loading);
+
+	void loadListFinished();
+
+	void loadListFailed(QString msg);
+
+private:
+	QList<PtrLWJGLVersion> m_vlist;
+
+	QNetworkReply *m_netReply;
+	QNetworkReply *reply;
+
+	bool m_loading;
+	bool m_errored;
+	QString m_lastErrorMsg;
+
+	void failed(QString msg);
+
+	void finished();
+
+	void setLoading(bool loading);
+
+private
+slots:
+	virtual void netRequestComplete();
+};
diff --git a/libraries/logic/minecraft/liteloader/LiteLoaderInstaller.cpp b/libraries/logic/minecraft/liteloader/LiteLoaderInstaller.cpp
new file mode 100644
index 00000000..25297fa4
--- /dev/null
+++ b/libraries/logic/minecraft/liteloader/LiteLoaderInstaller.cpp
@@ -0,0 +1,142 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LiteLoaderInstaller.h"
+
+#include <QJsonArray>
+#include <QJsonDocument>
+
+#include <QDebug>
+
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/Library.h"
+#include "minecraft/onesix/OneSixInstance.h"
+#include <minecraft/onesix/OneSixVersionFormat.h>
+#include "minecraft/liteloader/LiteLoaderVersionList.h"
+#include "Exception.h"
+
+LiteLoaderInstaller::LiteLoaderInstaller() : BaseInstaller()
+{
+}
+
+void LiteLoaderInstaller::prepare(LiteLoaderVersionPtr version)
+{
+	m_version = version;
+}
+bool LiteLoaderInstaller::add(OneSixInstance *to)
+{
+	if (!BaseInstaller::add(to))
+	{
+		return false;
+	}
+
+	QJsonObject obj;
+
+	obj.insert("mainClass", QString("net.minecraft.launchwrapper.Launch"));
+	obj.insert("+tweakers", QJsonArray::fromStringList(QStringList() << m_version->tweakClass));
+	obj.insert("order", 10);
+
+	QJsonArray libraries;
+
+	for (auto Library : m_version->libraries)
+	{
+		libraries.append(OneSixVersionFormat::libraryToJson(Library.get()));
+	}
+
+	// liteloader
+	{
+		Library liteloaderLib("com.mumfrey:liteloader:" + m_version->version);
+		liteloaderLib.setAbsoluteUrl(QString("http://dl.liteloader.com/versions/com/mumfrey/liteloader/%1/%2").arg(m_version->mcVersion, m_version->file));
+		QJsonObject llLibObj = OneSixVersionFormat::libraryToJson(&liteloaderLib);
+		libraries.append(llLibObj);
+	}
+
+	obj.insert("+libraries", libraries);
+	obj.insert("name", QString("LiteLoader"));
+	obj.insert("fileId", id());
+	obj.insert("version", m_version->version);
+	obj.insert("mcVersion", to->intendedVersionId());
+
+	QFile file(filename(to->instanceRoot()));
+	if (!file.open(QFile::WriteOnly))
+	{
+		qCritical() << "Error opening" << file.fileName()
+					 << "for reading:" << file.errorString();
+		return false;
+	}
+	file.write(QJsonDocument(obj).toJson());
+	file.close();
+
+	return true;
+}
+
+class LiteLoaderInstallTask : public Task
+{
+	Q_OBJECT
+public:
+	LiteLoaderInstallTask(LiteLoaderInstaller *installer, OneSixInstance *instance,
+						  BaseVersionPtr version, QObject *parent)
+		: Task(parent), m_installer(installer), m_instance(instance), m_version(version)
+	{
+	}
+
+protected:
+	void executeTask() override
+	{
+		LiteLoaderVersionPtr liteloaderVersion =
+			std::dynamic_pointer_cast<LiteLoaderVersion>(m_version);
+		if (!liteloaderVersion)
+		{
+			return;
+		}
+		m_installer->prepare(liteloaderVersion);
+		if (!m_installer->add(m_instance))
+		{
+			emitFailed(tr("For reasons unknown, the LiteLoader installation failed. Check your "
+						  "MultiMC log files for details."));
+		}
+		else
+		{
+			try
+			{
+				m_instance->reloadProfile();
+				emitSucceeded();
+			}
+			catch (Exception &e)
+			{
+				emitFailed(e.cause());
+			}
+			catch (...)
+			{
+				emitFailed(
+					tr("Failed to load the version description file for reasons unknown."));
+			}
+		}
+	}
+
+private:
+	LiteLoaderInstaller *m_installer;
+	OneSixInstance *m_instance;
+	BaseVersionPtr m_version;
+};
+
+Task *LiteLoaderInstaller::createInstallTask(OneSixInstance *instance,
+														 BaseVersionPtr version,
+														 QObject *parent)
+{
+	return new LiteLoaderInstallTask(this, instance, version, parent);
+}
+
+#include "LiteLoaderInstaller.moc"
diff --git a/libraries/logic/minecraft/liteloader/LiteLoaderInstaller.h b/libraries/logic/minecraft/liteloader/LiteLoaderInstaller.h
new file mode 100644
index 00000000..fe0aee3d
--- /dev/null
+++ b/libraries/logic/minecraft/liteloader/LiteLoaderInstaller.h
@@ -0,0 +1,39 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QMap>
+
+#include "BaseInstaller.h"
+#include "LiteLoaderVersionList.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT LiteLoaderInstaller : public BaseInstaller
+{
+public:
+	LiteLoaderInstaller();
+
+	void prepare(LiteLoaderVersionPtr version);
+	bool add(OneSixInstance *to) override;
+	virtual QString id() const override { return "com.mumfrey.liteloader"; }
+
+	Task *createInstallTask(OneSixInstance *instance, BaseVersionPtr version, QObject *parent) override;
+
+private:
+	LiteLoaderVersionPtr m_version;
+};
diff --git a/libraries/logic/minecraft/liteloader/LiteLoaderVersionList.cpp b/libraries/logic/minecraft/liteloader/LiteLoaderVersionList.cpp
new file mode 100644
index 00000000..b0c9736a
--- /dev/null
+++ b/libraries/logic/minecraft/liteloader/LiteLoaderVersionList.cpp
@@ -0,0 +1,276 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LiteLoaderVersionList.h"
+#include <minecraft/onesix/OneSixVersionFormat.h>
+#include "Env.h"
+#include "net/URLConstants.h"
+#include "Exception.h"
+
+#include <QtXml>
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QJsonValue>
+#include <QJsonParseError>
+
+#include <QtAlgorithms>
+
+#include <QtNetwork>
+
+LiteLoaderVersionList::LiteLoaderVersionList(QObject *parent) : BaseVersionList(parent)
+{
+}
+
+Task *LiteLoaderVersionList::getLoadTask()
+{
+	return new LLListLoadTask(this);
+}
+
+bool LiteLoaderVersionList::isLoaded()
+{
+	return m_loaded;
+}
+
+const BaseVersionPtr LiteLoaderVersionList::at(int i) const
+{
+	return m_vlist.at(i);
+}
+
+int LiteLoaderVersionList::count() const
+{
+	return m_vlist.count();
+}
+
+static bool cmpVersions(BaseVersionPtr first, BaseVersionPtr second)
+{
+	auto left = std::dynamic_pointer_cast<LiteLoaderVersion>(first);
+	auto right = std::dynamic_pointer_cast<LiteLoaderVersion>(second);
+	return left->timestamp > right->timestamp;
+}
+
+void LiteLoaderVersionList::sortVersions()
+{
+	beginResetModel();
+	std::sort(m_vlist.begin(), m_vlist.end(), cmpVersions);
+	endResetModel();
+}
+
+QVariant LiteLoaderVersionList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid())
+		return QVariant();
+
+	if (index.row() > count())
+		return QVariant();
+
+	auto version = std::dynamic_pointer_cast<LiteLoaderVersion>(m_vlist[index.row()]);
+	switch (role)
+	{
+	case VersionPointerRole:
+		return qVariantFromValue(m_vlist[index.row()]);
+
+	case VersionRole:
+		return version->name();
+
+	case VersionIdRole:
+		return version->descriptor();
+
+	case ParentGameVersionRole:
+		return version->mcVersion;
+
+	case RecommendedRole:
+		return version->isLatest;
+
+	default:
+		return QVariant();
+	}
+}
+
+QList<BaseVersionList::ModelRoles> LiteLoaderVersionList::providesRoles()
+{
+	return {VersionPointerRole, VersionRole, VersionIdRole, ParentGameVersionRole, RecommendedRole};
+}
+
+BaseVersionPtr LiteLoaderVersionList::getLatestStable() const
+{
+	for (int i = 0; i < m_vlist.length(); i++)
+	{
+		auto ver = std::dynamic_pointer_cast<LiteLoaderVersion>(m_vlist.at(i));
+		if (ver->isLatest)
+		{
+			return m_vlist.at(i);
+		}
+	}
+	return BaseVersionPtr();
+}
+
+void LiteLoaderVersionList::updateListData(QList<BaseVersionPtr> versions)
+{
+	beginResetModel();
+	m_vlist = versions;
+	m_loaded = true;
+	std::sort(m_vlist.begin(), m_vlist.end(), cmpVersions);
+	endResetModel();
+}
+
+LLListLoadTask::LLListLoadTask(LiteLoaderVersionList *vlist)
+{
+	m_list = vlist;
+}
+
+LLListLoadTask::~LLListLoadTask()
+{
+}
+
+void LLListLoadTask::executeTask()
+{
+	setStatus(tr("Loading LiteLoader version list..."));
+	auto job = new NetJob("Version index");
+	// we do not care if the version is stale or not.
+	auto liteloaderEntry = ENV.metacache()->resolveEntry("liteloader", "versions.json");
+
+	// verify by poking the server.
+	liteloaderEntry->setStale(true);
+
+	job->addNetAction(listDownload = CacheDownload::make(QUrl(URLConstants::LITELOADER_URL),
+														 liteloaderEntry));
+
+	connect(listDownload.get(), SIGNAL(failed(int)), SLOT(listFailed()));
+
+	listJob.reset(job);
+	connect(listJob.get(), SIGNAL(succeeded()), SLOT(listDownloaded()));
+	connect(listJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	listJob->start();
+}
+
+void LLListLoadTask::listFailed()
+{
+	emitFailed("Failed to load LiteLoader version list.");
+	return;
+}
+
+void LLListLoadTask::listDownloaded()
+{
+	QByteArray data;
+	{
+		auto dlJob = listDownload;
+		auto filename = std::dynamic_pointer_cast<CacheDownload>(dlJob)->getTargetFilepath();
+		QFile listFile(filename);
+		if (!listFile.open(QIODevice::ReadOnly))
+		{
+			emitFailed("Failed to open the LiteLoader version list.");
+			return;
+		}
+		data = listFile.readAll();
+		listFile.close();
+		dlJob.reset();
+	}
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		emitFailed("Error parsing version list JSON:" + jsonError.errorString());
+		return;
+	}
+
+	if (!jsonDoc.isObject())
+	{
+		emitFailed("Error parsing version list JSON: jsonDoc is not an object");
+		return;
+	}
+
+	const QJsonObject root = jsonDoc.object();
+
+	// Now, get the array of versions.
+	if (!root.value("versions").isObject())
+	{
+		emitFailed("Error parsing version list JSON: missing 'versions' object");
+		return;
+	}
+
+	auto meta = root.value("meta").toObject();
+	QString description = meta.value("description").toString(tr("This is a lightweight loader for mods that don't change game mechanics."));
+	QString defaultUrl = meta.value("url").toString("http://dl.liteloader.com");
+	QString authors = meta.value("authors").toString("Mumfrey");
+	auto versions = root.value("versions").toObject();
+
+	QList<BaseVersionPtr> tempList;
+	for (auto vIt = versions.begin(); vIt != versions.end(); ++vIt)
+	{
+		const QString mcVersion = vIt.key();
+		QString latest;
+		const QJsonObject artefacts = vIt.value()
+										  .toObject()
+										  .value("artefacts")
+										  .toObject()
+										  .value("com.mumfrey:liteloader")
+										  .toObject();
+		QList<BaseVersionPtr> perMcVersionList;
+		for (auto aIt = artefacts.begin(); aIt != artefacts.end(); ++aIt)
+		{
+			const QString identifier = aIt.key();
+			const QJsonObject artefact = aIt.value().toObject();
+			if (identifier == "latest")
+			{
+				latest = artefact.value("version").toString();
+				continue;
+			}
+			LiteLoaderVersionPtr version(new LiteLoaderVersion());
+			version->version = artefact.value("version").toString();
+			version->file = artefact.value("file").toString();
+			version->mcVersion = mcVersion;
+			version->md5 = artefact.value("md5").toString();
+			version->timestamp = artefact.value("timestamp").toString().toInt();
+			version->tweakClass = artefact.value("tweakClass").toString();
+			version->authors = authors;
+			version->description = description;
+			version->defaultUrl = defaultUrl;
+			const QJsonArray libs = artefact.value("libraries").toArray();
+			for (auto lIt = libs.begin(); lIt != libs.end(); ++lIt)
+			{
+				auto libobject = (*lIt).toObject();
+				try
+				{
+					auto lib = OneSixVersionFormat::libraryFromJson(libobject, "versions.json");
+					// hack to make liteloader 1.7.10_00 work
+					if(lib->rawName() == GradleSpecifier("org.ow2.asm:asm-all:5.0.3"))
+					{
+						lib->setRepositoryURL("http://repo.maven.apache.org/maven2/");
+					}
+					version->libraries.append(lib);
+				}
+				catch (Exception &e)
+				{
+					qCritical() << "Couldn't read JSON object:";
+					continue;
+				}
+			}
+			perMcVersionList.append(version);
+		}
+		for (auto version : perMcVersionList)
+		{
+			auto v = std::dynamic_pointer_cast<LiteLoaderVersion>(version);
+			v->isLatest = v->version == latest;
+		}
+		tempList.append(perMcVersionList);
+	}
+	m_list->updateListData(tempList);
+
+	emitSucceeded();
+}
diff --git a/libraries/logic/minecraft/liteloader/LiteLoaderVersionList.h b/libraries/logic/minecraft/liteloader/LiteLoaderVersionList.h
new file mode 100644
index 00000000..1dba4b6a
--- /dev/null
+++ b/libraries/logic/minecraft/liteloader/LiteLoaderVersionList.h
@@ -0,0 +1,119 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+
+#include <QString>
+#include <QStringList>
+#include "BaseVersion.h"
+#include "BaseVersionList.h"
+#include "tasks/Task.h"
+#include "net/NetJob.h"
+#include <minecraft/Library.h>
+
+#include "multimc_logic_export.h"
+
+class LLListLoadTask;
+class QNetworkReply;
+
+class LiteLoaderVersion : public BaseVersion
+{
+public:
+	QString descriptor() override
+	{
+		if (isLatest)
+		{
+			return QObject::tr("Latest");
+		}
+		return QString();
+	}
+	QString typeString() const override
+	{
+		return mcVersion;
+	}
+	QString name() override
+	{
+		return version;
+	}
+
+	// important info
+	QString version;
+	QString file;
+	QString mcVersion;
+	QString md5;
+	int timestamp;
+	bool isLatest;
+	QString tweakClass;
+	QList<LibraryPtr> libraries;
+
+	// meta
+	QString defaultUrl;
+	QString description;
+	QString authors;
+};
+typedef std::shared_ptr<LiteLoaderVersion> LiteLoaderVersionPtr;
+
+class MULTIMC_LOGIC_EXPORT LiteLoaderVersionList : public BaseVersionList
+{
+	Q_OBJECT
+public:
+	friend class LLListLoadTask;
+
+	explicit LiteLoaderVersionList(QObject *parent = 0);
+
+	virtual Task *getLoadTask();
+	virtual bool isLoaded();
+	virtual const BaseVersionPtr at(int i) const;
+	virtual int count() const;
+	virtual void sortVersions();
+    virtual QVariant data ( const QModelIndex & index, int role = Qt::DisplayRole ) const;
+    virtual QList< ModelRoles > providesRoles();
+
+	virtual BaseVersionPtr getLatestStable() const;
+
+protected:
+	QList<BaseVersionPtr> m_vlist;
+
+	bool m_loaded = false;
+
+protected
+slots:
+	virtual void updateListData(QList<BaseVersionPtr> versions);
+};
+
+class LLListLoadTask : public Task
+{
+	Q_OBJECT
+
+public:
+	explicit LLListLoadTask(LiteLoaderVersionList *vlist);
+	~LLListLoadTask();
+
+	virtual void executeTask();
+
+protected
+slots:
+	void listDownloaded();
+	void listFailed();
+
+protected:
+	NetJobPtr listJob;
+	CacheDownloadPtr listDownload;
+	LiteLoaderVersionList *m_list;
+};
+
+Q_DECLARE_METATYPE(LiteLoaderVersionPtr)
diff --git a/libraries/logic/minecraft/onesix/OneSixInstance.cpp b/libraries/logic/minecraft/onesix/OneSixInstance.cpp
new file mode 100644
index 00000000..258e26c5
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixInstance.cpp
@@ -0,0 +1,597 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QDebug>
+#include <Env.h>
+
+#include "OneSixInstance.h"
+#include "OneSixUpdate.h"
+#include "OneSixProfileStrategy.h"
+
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/VersionBuildError.h"
+#include "launch/LaunchTask.h"
+#include "launch/steps/PreLaunchCommand.h"
+#include "launch/steps/Update.h"
+#include "launch/steps/LaunchMinecraft.h"
+#include "launch/steps/PostLaunchCommand.h"
+#include "launch/steps/TextPrint.h"
+#include "launch/steps/ModMinecraftJar.h"
+#include "launch/steps/CheckJava.h"
+#include "MMCZip.h"
+
+#include "minecraft/AssetsUtils.h"
+#include "minecraft/WorldList.h"
+#include <FileSystem.h>
+
+OneSixInstance::OneSixInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir)
+	: MinecraftInstance(globalSettings, settings, rootDir)
+{
+	m_settings->registerSetting({"IntendedVersion", "MinecraftVersion"}, "");
+}
+
+void OneSixInstance::init()
+{
+	createProfile();
+}
+
+void OneSixInstance::createProfile()
+{
+	m_profile.reset(new MinecraftProfile(new OneSixProfileStrategy(this)));
+}
+
+QSet<QString> OneSixInstance::traits()
+{
+	auto version = getMinecraftProfile();
+	if (!version)
+	{
+		return {"version-incomplete"};
+	}
+	else
+	{
+		return version->getTraits();
+	}
+}
+
+std::shared_ptr<Task> OneSixInstance::createUpdateTask()
+{
+	return std::shared_ptr<Task>(new OneSixUpdate(this));
+}
+
+QString replaceTokensIn(QString text, QMap<QString, QString> with)
+{
+	QString result;
+	QRegExp token_regexp("\\$\\{(.+)\\}");
+	token_regexp.setMinimal(true);
+	QStringList list;
+	int tail = 0;
+	int head = 0;
+	while ((head = token_regexp.indexIn(text, head)) != -1)
+	{
+		result.append(text.mid(tail, head - tail));
+		QString key = token_regexp.cap(1);
+		auto iter = with.find(key);
+		if (iter != with.end())
+		{
+			result.append(*iter);
+		}
+		head += token_regexp.matchedLength();
+		tail = head;
+	}
+	result.append(text.mid(tail));
+	return result;
+}
+
+QStringList OneSixInstance::processMinecraftArgs(AuthSessionPtr session)
+{
+	QString args_pattern = m_profile->getMinecraftArguments();
+	for (auto tweaker : m_profile->getTweakers())
+	{
+		args_pattern += " --tweakClass " + tweaker;
+	}
+
+	QMap<QString, QString> token_mapping;
+	// yggdrasil!
+	token_mapping["auth_username"] = session->username;
+	token_mapping["auth_session"] = session->session;
+	token_mapping["auth_access_token"] = session->access_token;
+	token_mapping["auth_player_name"] = session->player_name;
+	token_mapping["auth_uuid"] = session->uuid;
+
+	// blatant self-promotion.
+	token_mapping["profile_name"] = token_mapping["version_name"] = "MultiMC5";
+	if(m_profile->isVanilla())
+	{
+		token_mapping["version_type"] = m_profile->getMinecraftVersionType();
+	}
+	else
+	{
+		token_mapping["version_type"] = "custom";
+	}
+
+	QString absRootDir = QDir(minecraftRoot()).absolutePath();
+	token_mapping["game_directory"] = absRootDir;
+	QString absAssetsDir = QDir("assets/").absolutePath();
+	auto assets = m_profile->getMinecraftAssets();
+	token_mapping["game_assets"] = AssetsUtils::reconstructAssets(assets->id).absolutePath();
+
+	token_mapping["user_properties"] = session->serializeUserProperties();
+	token_mapping["user_type"] = session->user_type;
+
+	// 1.7.3+ assets tokens
+	token_mapping["assets_root"] = absAssetsDir;
+	token_mapping["assets_index_name"] = assets->id;
+
+	QStringList parts = args_pattern.split(' ', QString::SkipEmptyParts);
+	for (int i = 0; i < parts.length(); i++)
+	{
+		parts[i] = replaceTokensIn(parts[i], token_mapping);
+	}
+	return parts;
+}
+
+QString OneSixInstance::createLaunchScript(AuthSessionPtr session)
+{
+	QString launchScript;
+
+	if (!m_profile)
+		return nullptr;
+
+	for(auto & mod: loaderModList()->allMods())
+	{
+		if(!mod.enabled())
+			continue;
+		if(mod.type() == Mod::MOD_FOLDER)
+			continue;
+		// TODO: proper implementation would need to descend into folders.
+
+		launchScript += "mod " + mod.filename().completeBaseName()  + "\n";;
+	}
+
+	for(auto & coremod: coreModList()->allMods())
+	{
+		if(!coremod.enabled())
+			continue;
+		if(coremod.type() == Mod::MOD_FOLDER)
+			continue;
+		// TODO: proper implementation would need to descend into folders.
+
+		launchScript += "coremod " + coremod.filename().completeBaseName()  + "\n";;
+	}
+
+	for(auto & jarmod: m_profile->getJarMods())
+	{
+		launchScript += "jarmod " + jarmod->originalName + " (" + jarmod->name + ")\n";
+	}
+
+	auto mainClass = m_profile->getMainClass();
+	if (!mainClass.isEmpty())
+	{
+		launchScript += "mainClass " + mainClass + "\n";
+	}
+	auto appletClass = m_profile->getAppletClass();
+	if (!appletClass.isEmpty())
+	{
+		launchScript += "appletClass " + appletClass + "\n";
+	}
+
+	// generic minecraft params
+	for (auto param : processMinecraftArgs(session))
+	{
+		launchScript += "param " + param + "\n";
+	}
+
+	// window size, title and state, legacy
+	{
+		QString windowParams;
+		if (settings()->get("LaunchMaximized").toBool())
+			windowParams = "max";
+		else
+			windowParams = QString("%1x%2")
+							   .arg(settings()->get("MinecraftWinWidth").toInt())
+							   .arg(settings()->get("MinecraftWinHeight").toInt());
+		launchScript += "windowTitle " + windowTitle() + "\n";
+		launchScript += "windowParams " + windowParams + "\n";
+	}
+
+	// legacy auth
+	{
+		launchScript += "userName " + session->player_name + "\n";
+		launchScript += "sessionId " + session->session + "\n";
+	}
+
+	// libraries and class path.
+	{
+		auto libs = m_profile->getLibraries();
+
+		QStringList jar, native, native32, native64;
+		for (auto lib : libs)
+		{
+			lib->getApplicableFiles(currentSystem, jar, native, native32, native64);
+		}
+		for(auto file: jar)
+		{
+			launchScript += "cp " + file + "\n";
+		}
+		for(auto file: native)
+		{
+			launchScript += "ext " + file + "\n";
+		}
+		for(auto file: native32)
+		{
+			launchScript += "ext32 " + file + "\n";
+		}
+		for(auto file: native64)
+		{
+			launchScript += "ext64 " + file + "\n";
+		}
+		QDir natives_dir(FS::PathCombine(instanceRoot(), "natives/"));
+		launchScript += "natives " + natives_dir.absolutePath() + "\n";
+		auto jarMods = getJarMods();
+		if (!jarMods.isEmpty())
+		{
+			launchScript += "cp " + QDir(instanceRoot()).absoluteFilePath("minecraft.jar") + "\n";
+		}
+		else
+		{
+			QString relpath = m_profile->getMinecraftVersion() + "/" + m_profile->getMinecraftVersion() + ".jar";
+			launchScript += "cp " + versionsPath().absoluteFilePath(relpath) + "\n";
+		}
+	}
+
+	// traits. including legacyLaunch and others ;)
+	for (auto trait : m_profile->getTraits())
+	{
+		launchScript += "traits " + trait + "\n";
+	}
+	launchScript += "launcher onesix\n";
+	return launchScript;
+}
+
+std::shared_ptr<LaunchTask> OneSixInstance::createLaunchTask(AuthSessionPtr session)
+{
+	auto process = LaunchTask::create(std::dynamic_pointer_cast<MinecraftInstance>(getSharedPtr()));
+	auto pptr = process.get();
+
+	// print a header
+	{
+		process->appendStep(std::make_shared<TextPrint>(pptr, "Minecraft folder is:\n" + minecraftRoot() + "\n\n", MessageLevel::MultiMC));
+	}
+	{
+		auto step = std::make_shared<CheckJava>(pptr);
+		process->appendStep(step);
+	}
+	// run pre-launch command if that's needed
+	if(getPreLaunchCommand().size())
+	{
+		auto step = std::make_shared<PreLaunchCommand>(pptr);
+		step->setWorkingDirectory(minecraftRoot());
+		process->appendStep(step);
+	}
+	// if we aren't in offline mode,.
+	if(session->status != AuthSession::PlayableOffline)
+	{
+		process->appendStep(std::make_shared<Update>(pptr));
+	}
+	// if there are any jar mods
+	if(getJarMods().size())
+	{
+		auto step = std::make_shared<ModMinecraftJar>(pptr);
+		process->appendStep(step);
+	}
+	// actually launch the game
+	{
+		auto step = std::make_shared<LaunchMinecraft>(pptr);
+		step->setWorkingDirectory(minecraftRoot());
+		step->setAuthSession(session);
+		process->appendStep(step);
+	}
+	// run post-exit command if that's needed
+	if(getPostExitCommand().size())
+	{
+		auto step = std::make_shared<PostLaunchCommand>(pptr);
+		step->setWorkingDirectory(minecraftRoot());
+		process->appendStep(step);
+	}
+	if (session)
+	{
+		process->setCensorFilter(createCensorFilterFromSession(session));
+	}
+	return process;
+}
+
+std::shared_ptr<Task> OneSixInstance::createJarModdingTask()
+{
+	class JarModTask : public Task
+	{
+	public:
+		explicit JarModTask(std::shared_ptr<OneSixInstance> inst) : Task(nullptr), m_inst(inst)
+		{
+		}
+		virtual void executeTask()
+		{
+			auto profile = m_inst->getMinecraftProfile();
+			// nuke obsolete stripped jar(s) if needed
+			QString version_id = profile->getMinecraftVersion();
+			QString strippedPath = version_id + "/" + version_id + "-stripped.jar";
+			QFile strippedJar(strippedPath);
+			if(strippedJar.exists())
+			{
+				strippedJar.remove();
+			}
+			auto tempJarPath = QDir(m_inst->instanceRoot()).absoluteFilePath("temp.jar");
+			QFile tempJar(tempJarPath);
+			if(tempJar.exists())
+			{
+				tempJar.remove();
+			}
+			auto finalJarPath = QDir(m_inst->instanceRoot()).absoluteFilePath("minecraft.jar");
+			QFile finalJar(finalJarPath);
+			if(finalJar.exists())
+			{
+				if(!finalJar.remove())
+				{
+					emitFailed(tr("Couldn't remove stale jar file: %1").arg(finalJarPath));
+					return;
+				}
+			}
+
+			// create temporary modded jar, if needed
+			auto jarMods = m_inst->getJarMods();
+			if(jarMods.size())
+			{
+				auto sourceJarPath = m_inst->versionsPath().absoluteFilePath(version_id + "/" + version_id + ".jar");
+				QString localPath = version_id + "/" + version_id + ".jar";
+				auto metacache = ENV.metacache();
+				auto entry = metacache->resolveEntry("versions", localPath);
+				QString fullJarPath = entry->getFullPath();
+				if(!MMCZip::createModdedJar(sourceJarPath, finalJarPath, jarMods))
+				{
+					emitFailed(tr("Failed to create the custom Minecraft jar file."));
+					return;
+				}
+			}
+			emitSucceeded();
+		}
+		std::shared_ptr<OneSixInstance> m_inst;
+	};
+	return std::make_shared<JarModTask>(std::dynamic_pointer_cast<OneSixInstance>(shared_from_this()));
+}
+
+void OneSixInstance::cleanupAfterRun()
+{
+	QString target_dir = FS::PathCombine(instanceRoot(), "natives/");
+	QDir dir(target_dir);
+	dir.removeRecursively();
+}
+
+std::shared_ptr<ModList> OneSixInstance::loaderModList() const
+{
+	if (!m_loader_mod_list)
+	{
+		m_loader_mod_list.reset(new ModList(loaderModsDir()));
+	}
+	m_loader_mod_list->update();
+	return m_loader_mod_list;
+}
+
+std::shared_ptr<ModList> OneSixInstance::coreModList() const
+{
+	if (!m_core_mod_list)
+	{
+		m_core_mod_list.reset(new ModList(coreModsDir()));
+	}
+	m_core_mod_list->update();
+	return m_core_mod_list;
+}
+
+std::shared_ptr<ModList> OneSixInstance::resourcePackList() const
+{
+	if (!m_resource_pack_list)
+	{
+		m_resource_pack_list.reset(new ModList(resourcePacksDir()));
+	}
+	m_resource_pack_list->update();
+	return m_resource_pack_list;
+}
+
+std::shared_ptr<ModList> OneSixInstance::texturePackList() const
+{
+	if (!m_texture_pack_list)
+	{
+		m_texture_pack_list.reset(new ModList(texturePacksDir()));
+	}
+	m_texture_pack_list->update();
+	return m_texture_pack_list;
+}
+
+std::shared_ptr<WorldList> OneSixInstance::worldList() const
+{
+	if (!m_world_list)
+	{
+		m_world_list.reset(new WorldList(worldDir()));
+	}
+	return m_world_list;
+}
+
+bool OneSixInstance::setIntendedVersionId(QString version)
+{
+	settings()->set("IntendedVersion", version);
+	if(getMinecraftProfile())
+	{
+		clearProfile();
+	}
+	emit propertiesChanged(this);
+	return true;
+}
+
+QList< Mod > OneSixInstance::getJarMods() const
+{
+	QList<Mod> mods;
+	for (auto jarmod : m_profile->getJarMods())
+	{
+		QString filePath = jarmodsPath().absoluteFilePath(jarmod->name);
+		mods.push_back(Mod(QFileInfo(filePath)));
+	}
+	return mods;
+}
+
+
+QString OneSixInstance::intendedVersionId() const
+{
+	return settings()->get("IntendedVersion").toString();
+}
+
+void OneSixInstance::setShouldUpdate(bool)
+{
+}
+
+bool OneSixInstance::shouldUpdate() const
+{
+	return true;
+}
+
+QString OneSixInstance::currentVersionId() const
+{
+	return intendedVersionId();
+}
+
+void OneSixInstance::reloadProfile()
+{
+	m_profile->reload();
+	auto severity = m_profile->getProblemSeverity();
+	if(severity == ProblemSeverity::PROBLEM_ERROR)
+	{
+		setFlag(VersionBrokenFlag);
+	}
+	else
+	{
+		unsetFlag(VersionBrokenFlag);
+	}
+	emit versionReloaded();
+}
+
+void OneSixInstance::clearProfile()
+{
+	m_profile->clear();
+	emit versionReloaded();
+}
+
+std::shared_ptr<MinecraftProfile> OneSixInstance::getMinecraftProfile() const
+{
+	return m_profile;
+}
+
+QDir OneSixInstance::librariesPath() const
+{
+	return QDir::current().absoluteFilePath("libraries");
+}
+
+QDir OneSixInstance::jarmodsPath() const
+{
+	return QDir(jarModsDir());
+}
+
+QDir OneSixInstance::versionsPath() const
+{
+	return QDir::current().absoluteFilePath("versions");
+}
+
+bool OneSixInstance::providesVersionFile() const
+{
+	return false;
+}
+
+bool OneSixInstance::reload()
+{
+	if (BaseInstance::reload())
+	{
+		try
+		{
+			reloadProfile();
+			return true;
+		}
+		catch (...)
+		{
+			return false;
+		}
+	}
+	return false;
+}
+
+QString OneSixInstance::loaderModsDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "mods");
+}
+
+QString OneSixInstance::coreModsDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "coremods");
+}
+
+QString OneSixInstance::resourcePacksDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "resourcepacks");
+}
+
+QString OneSixInstance::texturePacksDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "texturepacks");
+}
+
+QString OneSixInstance::instanceConfigFolder() const
+{
+	return FS::PathCombine(minecraftRoot(), "config");
+}
+
+QString OneSixInstance::jarModsDir() const
+{
+	return FS::PathCombine(instanceRoot(), "jarmods");
+}
+
+QString OneSixInstance::libDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "lib");
+}
+
+QString OneSixInstance::worldDir() const
+{
+	return FS::PathCombine(minecraftRoot(), "saves");
+}
+
+QStringList OneSixInstance::extraArguments() const
+{
+	auto list = BaseInstance::extraArguments();
+	auto version = getMinecraftProfile();
+	if (!version)
+		return list;
+	auto jarMods = getJarMods();
+	if (!jarMods.isEmpty())
+	{
+		list.append({"-Dfml.ignoreInvalidMinecraftCertificates=true",
+					 "-Dfml.ignorePatchDiscrepancies=true"});
+	}
+	return list;
+}
+
+std::shared_ptr<OneSixInstance> OneSixInstance::getSharedPtr()
+{
+	return std::dynamic_pointer_cast<OneSixInstance>(BaseInstance::getSharedPtr());
+}
+
+QString OneSixInstance::typeName() const
+{
+	return tr("OneSix");
+}
diff --git a/libraries/logic/minecraft/onesix/OneSixInstance.h b/libraries/logic/minecraft/onesix/OneSixInstance.h
new file mode 100644
index 00000000..2dfab48c
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixInstance.h
@@ -0,0 +1,117 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "minecraft/MinecraftInstance.h"
+
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/ModList.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT OneSixInstance : public MinecraftInstance
+{
+	Q_OBJECT
+public:
+	explicit OneSixInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+	virtual ~OneSixInstance(){};
+
+	virtual void init() override;
+
+	//////  Mod Lists  //////
+	std::shared_ptr<ModList> loaderModList() const;
+	std::shared_ptr<ModList> coreModList() const;
+	std::shared_ptr<ModList> resourcePackList() const override;
+	std::shared_ptr<ModList> texturePackList() const override;
+	std::shared_ptr<WorldList> worldList() const override;
+	virtual QList<Mod> getJarMods() const override;
+	virtual void createProfile();
+
+	virtual QSet<QString> traits() override;
+
+	////// Directories and files //////
+	QString jarModsDir() const;
+	QString resourcePacksDir() const;
+	QString texturePacksDir() const;
+	QString loaderModsDir() const;
+	QString coreModsDir() const;
+	QString libDir() const;
+	QString worldDir() const;
+	virtual QString instanceConfigFolder() const override;
+
+	virtual std::shared_ptr<Task> createUpdateTask() override;
+	virtual std::shared_ptr<LaunchTask> createLaunchTask(AuthSessionPtr account) override;
+	virtual std::shared_ptr<Task> createJarModdingTask() override;
+
+	virtual QString createLaunchScript(AuthSessionPtr session) override;
+
+	virtual void cleanupAfterRun() override;
+
+	virtual QString intendedVersionId() const override;
+	virtual bool setIntendedVersionId(QString version) override;
+
+	virtual QString currentVersionId() const override;
+
+	virtual bool shouldUpdate() const override;
+	virtual void setShouldUpdate(bool val) override;
+
+	/**
+	 * reload the profile, including version json files.
+	 *
+	 * throws various exceptions :3
+	 */
+	void reloadProfile();
+
+	/// clears all version information in preparation for an update
+	void clearProfile();
+
+	/// get the current full version info
+	std::shared_ptr<MinecraftProfile> getMinecraftProfile() const;
+
+	virtual QDir jarmodsPath() const;
+	virtual QDir librariesPath() const;
+	virtual QDir versionsPath() const;
+	virtual bool providesVersionFile() const;
+
+	bool reload() override;
+
+	virtual QStringList extraArguments() const override;
+
+	std::shared_ptr<OneSixInstance> getSharedPtr();
+
+	virtual QString typeName() const override;
+
+	bool canExport() const override
+	{
+		return true;
+	}
+
+signals:
+	void versionReloaded();
+
+private:
+	QStringList processMinecraftArgs(AuthSessionPtr account);
+
+protected:
+	std::shared_ptr<MinecraftProfile> m_profile;
+	mutable std::shared_ptr<ModList> m_loader_mod_list;
+	mutable std::shared_ptr<ModList> m_core_mod_list;
+	mutable std::shared_ptr<ModList> m_resource_pack_list;
+	mutable std::shared_ptr<ModList> m_texture_pack_list;
+	mutable std::shared_ptr<WorldList> m_world_list;
+};
+
+Q_DECLARE_METATYPE(std::shared_ptr<OneSixInstance>)
diff --git a/libraries/logic/minecraft/onesix/OneSixProfileStrategy.cpp b/libraries/logic/minecraft/onesix/OneSixProfileStrategy.cpp
new file mode 100644
index 00000000..af42286d
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixProfileStrategy.cpp
@@ -0,0 +1,418 @@
+#include "OneSixProfileStrategy.h"
+#include "OneSixInstance.h"
+#include "OneSixVersionFormat.h"
+
+#include "minecraft/VersionBuildError.h"
+#include "minecraft/MinecraftVersionList.h"
+#include "Env.h"
+#include <FileSystem.h>
+
+#include <QDir>
+#include <QUuid>
+#include <QJsonDocument>
+#include <QJsonArray>
+
+OneSixProfileStrategy::OneSixProfileStrategy(OneSixInstance* instance)
+{
+	m_instance = instance;
+}
+
+void OneSixProfileStrategy::upgradeDeprecatedFiles()
+{
+	auto versionJsonPath = FS::PathCombine(m_instance->instanceRoot(), "version.json");
+	auto customJsonPath = FS::PathCombine(m_instance->instanceRoot(), "custom.json");
+	auto mcJson = FS::PathCombine(m_instance->instanceRoot(), "patches" , "net.minecraft.json");
+
+	QString sourceFile;
+	QString renameFile;
+
+	// convert old crap.
+	if(QFile::exists(customJsonPath))
+	{
+		sourceFile = customJsonPath;
+		renameFile = versionJsonPath;
+	}
+	else if(QFile::exists(versionJsonPath))
+	{
+		sourceFile = versionJsonPath;
+	}
+	if(!sourceFile.isEmpty() && !QFile::exists(mcJson))
+	{
+		if(!FS::ensureFilePathExists(mcJson))
+		{
+			qWarning() << "Couldn't create patches folder for" << m_instance->name();
+			return;
+		}
+		if(!renameFile.isEmpty() && QFile::exists(renameFile))
+		{
+			if(!QFile::rename(renameFile, renameFile + ".old"))
+			{
+				qWarning() << "Couldn't rename" << renameFile << "to" << renameFile + ".old" << "in" << m_instance->name();
+				return;
+			}
+		}
+		auto file = ProfileUtils::parseJsonFile(QFileInfo(sourceFile), false);
+		ProfileUtils::removeLwjglFromPatch(file);
+		file->fileId = "net.minecraft";
+		file->version = file->minecraftVersion;
+		file->name = "Minecraft";
+		auto data = OneSixVersionFormat::versionFileToJson(file, false).toJson();
+		QSaveFile newPatchFile(mcJson);
+		if(!newPatchFile.open(QIODevice::WriteOnly))
+		{
+			newPatchFile.cancelWriting();
+			qWarning() << "Couldn't open main patch for writing in" << m_instance->name();
+			return;
+		}
+		newPatchFile.write(data);
+		if(!newPatchFile.commit())
+		{
+			qWarning() << "Couldn't save main patch in" << m_instance->name();
+			return;
+		}
+		if(!QFile::rename(sourceFile, sourceFile + ".old"))
+		{
+			qWarning() << "Couldn't rename" << sourceFile << "to" << sourceFile + ".old" << "in" << m_instance->name();
+			return;
+		}
+	}
+}
+
+void OneSixProfileStrategy::loadDefaultBuiltinPatches()
+{
+	{
+		auto mcJson = FS::PathCombine(m_instance->instanceRoot(), "patches" , "net.minecraft.json");
+		// load up the base minecraft patch
+		ProfilePatchPtr minecraftPatch;
+		if(QFile::exists(mcJson))
+		{
+			auto file = ProfileUtils::parseJsonFile(QFileInfo(mcJson), false);
+			if(file->version.isEmpty())
+			{
+				file->version = m_instance->intendedVersionId();
+			}
+			file->setVanilla(false);
+			file->setRevertible(true);
+			minecraftPatch = std::dynamic_pointer_cast<ProfilePatch>(file);
+		}
+		else
+		{
+			auto mcversion = ENV.getVersion("net.minecraft", m_instance->intendedVersionId());
+			minecraftPatch = std::dynamic_pointer_cast<ProfilePatch>(mcversion);
+		}
+		if (!minecraftPatch)
+		{
+			throw VersionIncomplete("net.minecraft");
+		}
+		minecraftPatch->setOrder(-2);
+		profile->appendPatch(minecraftPatch);
+	}
+
+	{
+		auto lwjglJson = FS::PathCombine(m_instance->instanceRoot(), "patches" , "org.lwjgl.json");
+		ProfilePatchPtr lwjglPatch;
+		if(QFile::exists(lwjglJson))
+		{
+			auto file = ProfileUtils::parseJsonFile(QFileInfo(lwjglJson), false);
+			file->setVanilla(false);
+			file->setRevertible(true);
+			lwjglPatch = std::dynamic_pointer_cast<ProfilePatch>(file);
+		}
+		else
+		{
+			// NOTE: this is obviously fake, is fixed in unstable.
+			QResource LWJGL(":/versions/LWJGL/2.9.1.json");
+			auto lwjgl = ProfileUtils::parseJsonFile(LWJGL.absoluteFilePath(), false);
+			lwjgl->setVanilla(true);
+			lwjgl->setCustomizable(true);
+			lwjglPatch = std::dynamic_pointer_cast<ProfilePatch>(lwjgl);
+		}
+		if (!lwjglPatch)
+		{
+			throw VersionIncomplete("org.lwjgl");
+		}
+		lwjglPatch->setOrder(-1);
+		profile->appendPatch(lwjglPatch);
+	}
+}
+
+void OneSixProfileStrategy::loadUserPatches()
+{
+	// load all patches, put into map for ordering, apply in the right order
+	ProfileUtils::PatchOrder userOrder;
+	ProfileUtils::readOverrideOrders(FS::PathCombine(m_instance->instanceRoot(), "order.json"), userOrder);
+	QDir patches(FS::PathCombine(m_instance->instanceRoot(),"patches"));
+	QSet<QString> seen_extra;
+
+	// first, load things by sort order.
+	for (auto id : userOrder)
+	{
+		// ignore builtins
+		if (id == "net.minecraft")
+			continue;
+		if (id == "org.lwjgl")
+			continue;
+		// parse the file
+		QString filename = patches.absoluteFilePath(id + ".json");
+		QFileInfo finfo(filename);
+		if(!finfo.exists())
+		{
+			qDebug() << "Patch file " << filename << " was deleted by external means...";
+			continue;
+		}
+		qDebug() << "Reading" << filename << "by user order";
+		VersionFilePtr file = ProfileUtils::parseJsonFile(finfo, false);
+		// sanity check. prevent tampering with files.
+		if (file->fileId != id)
+		{
+			file->addProblem(PROBLEM_WARNING, QObject::tr("load id %1 does not match internal id %2").arg(id, file->fileId));
+			seen_extra.insert(file->fileId);
+		}
+		file->setRemovable(true);
+		file->setMovable(true);
+		profile->appendPatch(file);
+	}
+	// now load the rest by internal preference.
+	QMultiMap<int, VersionFilePtr> files;
+	for (auto info : patches.entryInfoList(QStringList() << "*.json", QDir::Files))
+	{
+		// parse the file
+		qDebug() << "Reading" << info.fileName();
+		auto file = ProfileUtils::parseJsonFile(info, true);
+		// ignore builtins
+		if (file->fileId == "net.minecraft")
+			continue;
+		if (file->fileId == "org.lwjgl")
+			continue;
+		// do not load versions with broken IDs twice
+		if(seen_extra.contains(file->fileId))
+			continue;
+		// do not load what we already loaded in the first pass
+		if (userOrder.contains(file->fileId))
+			continue;
+		file->setRemovable(true);
+		file->setMovable(true);
+		files.insert(file->order, file);
+	}
+	QSet<int> seen;
+	for (auto order : files.keys())
+	{
+		if(seen.contains(order))
+			continue;
+		seen.insert(order);
+		const auto &values = files.values(order);
+		if(values.size() == 1)
+		{
+			profile->appendPatch(values[0]);
+			continue;
+		}
+		for(auto &file: values)
+		{
+			QStringList list;
+			for(auto &file2: values)
+			{
+				if(file != file2)
+					list.append(file2->name);
+			}
+			file->addProblem(PROBLEM_WARNING, QObject::tr("%1 has the same order as the following components:\n%2").arg(file->name, list.join(", ")));
+			profile->appendPatch(file);
+		}
+	}
+}
+
+
+void OneSixProfileStrategy::load()
+{
+	profile->clearPatches();
+
+	upgradeDeprecatedFiles();
+	loadDefaultBuiltinPatches();
+	loadUserPatches();
+}
+
+bool OneSixProfileStrategy::saveOrder(ProfileUtils::PatchOrder order)
+{
+	return ProfileUtils::writeOverrideOrders(FS::PathCombine(m_instance->instanceRoot(), "order.json"), order);
+}
+
+bool OneSixProfileStrategy::resetOrder()
+{
+	return QDir(m_instance->instanceRoot()).remove("order.json");
+}
+
+bool OneSixProfileStrategy::removePatch(ProfilePatchPtr patch)
+{
+	bool ok = true;
+	// first, remove the patch file. this ensures it's not used anymore
+	auto fileName = patch->getFilename();
+	if(fileName.size())
+	{
+		QFile patchFile(fileName);
+		if(patchFile.exists() && !patchFile.remove())
+		{
+			qCritical() << "File" << fileName << "could not be removed because:" << patchFile.errorString();
+			return false;
+		}
+	}
+
+
+	auto preRemoveJarMod = [&](JarmodPtr jarMod) -> bool
+	{
+		QString fullpath = FS::PathCombine(m_instance->jarModsDir(), jarMod->name);
+		QFileInfo finfo (fullpath);
+		if(finfo.exists())
+		{
+			QFile jarModFile(fullpath);
+			if(!jarModFile.remove())
+			{
+				qCritical() << "File" << fullpath << "could not be removed because:" << jarModFile.errorString();
+				return false;
+			}
+			return true;
+		}
+		return true;
+	};
+
+	for(auto &jarmod: patch->getJarMods())
+	{
+		ok &= preRemoveJarMod(jarmod);
+	}
+	return ok;
+}
+
+bool OneSixProfileStrategy::customizePatch(ProfilePatchPtr patch)
+{
+	if(patch->isCustom())
+	{
+		return false;
+	}
+
+	auto filename = FS::PathCombine(m_instance->instanceRoot(), "patches" , patch->getID() + ".json");
+	if(!FS::ensureFilePathExists(filename))
+	{
+		return false;
+	}
+	try
+	{
+		QSaveFile jsonFile(filename);
+		if(!jsonFile.open(QIODevice::WriteOnly))
+		{
+			return false;
+		}
+		auto vfile = patch->getVersionFile();
+		if(!vfile)
+		{
+			return false;
+		}
+		auto document = OneSixVersionFormat::versionFileToJson(vfile, true);
+		jsonFile.write(document.toJson());
+		if(!jsonFile.commit())
+		{
+			return false;
+		}
+		load();
+	}
+	catch (VersionIncomplete &error)
+	{
+		qDebug() << "Version was incomplete:" << error.cause();
+	}
+	catch (Exception &error)
+	{
+		qWarning() << "Version could not be loaded:" << error.cause();
+	}
+	return true;
+}
+
+bool OneSixProfileStrategy::revertPatch(ProfilePatchPtr patch)
+{
+	if(!patch->isCustom())
+	{
+		// already not custom
+		return true;
+	}
+	auto filename = patch->getFilename();
+	if(!QFile::exists(filename))
+	{
+		// already gone / not custom
+		return true;
+	}
+	// just kill the file and reload
+	bool result = QFile::remove(filename);
+	try
+	{
+		load();
+	}
+	catch (VersionIncomplete &error)
+	{
+		qDebug() << "Version was incomplete:" << error.cause();
+	}
+	catch (Exception &error)
+	{
+		qWarning() << "Version could not be loaded:" << error.cause();
+	}
+	return result;
+}
+
+bool OneSixProfileStrategy::installJarMods(QStringList filepaths)
+{
+	QString patchDir = FS::PathCombine(m_instance->instanceRoot(), "patches");
+	if(!FS::ensureFolderPathExists(patchDir))
+	{
+		return false;
+	}
+
+	if (!FS::ensureFolderPathExists(m_instance->jarModsDir()))
+	{
+		return false;
+	}
+
+	for(auto filepath:filepaths)
+	{
+		QFileInfo sourceInfo(filepath);
+		auto uuid = QUuid::createUuid();
+		QString id = uuid.toString().remove('{').remove('}');
+		QString target_filename = id + ".jar";
+		QString target_id = "org.multimc.jarmod." + id;
+		QString target_name = sourceInfo.completeBaseName() + " (jar mod)";
+		QString finalPath = FS::PathCombine(m_instance->jarModsDir(), target_filename);
+
+		QFileInfo targetInfo(finalPath);
+		if(targetInfo.exists())
+		{
+			return false;
+		}
+
+		if (!QFile::copy(sourceInfo.absoluteFilePath(),QFileInfo(finalPath).absoluteFilePath()))
+		{
+			return false;
+		}
+
+		auto f = std::make_shared<VersionFile>();
+		auto jarMod = std::make_shared<Jarmod>();
+		jarMod->name = target_filename;
+		jarMod->originalName = sourceInfo.completeBaseName();
+		f->jarMods.append(jarMod);
+		f->name = target_name;
+		f->fileId = target_id;
+		f->order = profile->getFreeOrderNumber();
+		QString patchFileName = FS::PathCombine(patchDir, target_id + ".json");
+		f->filename = patchFileName;
+		f->setMovable(true);
+		f->setRemovable(true);
+
+		QFile file(patchFileName);
+		if (!file.open(QFile::WriteOnly))
+		{
+			qCritical() << "Error opening" << file.fileName()
+						<< "for reading:" << file.errorString();
+			return false;
+		}
+		file.write(OneSixVersionFormat::versionFileToJson(f, true).toJson());
+		file.close();
+		profile->appendPatch(f);
+	}
+	profile->saveCurrentOrder();
+	profile->reapplyPatches();
+	return true;
+}
+
diff --git a/libraries/logic/minecraft/onesix/OneSixProfileStrategy.h b/libraries/logic/minecraft/onesix/OneSixProfileStrategy.h
new file mode 100644
index 00000000..96c1ba7b
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixProfileStrategy.h
@@ -0,0 +1,26 @@
+#pragma once
+#include "minecraft/ProfileStrategy.h"
+
+class OneSixInstance;
+
+class OneSixProfileStrategy : public ProfileStrategy
+{
+public:
+	OneSixProfileStrategy(OneSixInstance * instance);
+	virtual ~OneSixProfileStrategy() {};
+	virtual void load() override;
+	virtual bool resetOrder() override;
+	virtual bool saveOrder(ProfileUtils::PatchOrder order) override;
+	virtual bool installJarMods(QStringList filepaths) override;
+	virtual bool removePatch(ProfilePatchPtr patch) override;
+	virtual bool customizePatch(ProfilePatchPtr patch) override;
+	virtual bool revertPatch(ProfilePatchPtr patch) override;
+
+protected:
+	virtual void loadDefaultBuiltinPatches();
+	virtual void loadUserPatches();
+	void upgradeDeprecatedFiles();
+
+protected:
+	OneSixInstance *m_instance;
+};
diff --git a/libraries/logic/minecraft/onesix/OneSixUpdate.cpp b/libraries/logic/minecraft/onesix/OneSixUpdate.cpp
new file mode 100644
index 00000000..1c2cd196
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixUpdate.cpp
@@ -0,0 +1,342 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Env.h"
+#include <minecraft/forge/ForgeXzDownload.h>
+#include "OneSixUpdate.h"
+#include "OneSixInstance.h"
+
+#include <QtNetwork>
+
+#include <QFile>
+#include <QFileInfo>
+#include <QTextStream>
+#include <QDataStream>
+#include <JlCompress.h>
+
+#include "BaseInstance.h"
+#include "minecraft/MinecraftVersionList.h"
+#include "minecraft/MinecraftProfile.h"
+#include "minecraft/Library.h"
+#include "net/URLConstants.h"
+#include "minecraft/AssetsUtils.h"
+#include "Exception.h"
+#include "MMCZip.h"
+#include <FileSystem.h>
+
+OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
+{
+}
+
+void OneSixUpdate::executeTask()
+{
+	// Make directories
+	QDir mcDir(m_inst->minecraftRoot());
+	if (!mcDir.exists() && !mcDir.mkpath("."))
+	{
+		emitFailed(tr("Failed to create folder for minecraft binaries."));
+		return;
+	}
+
+	// Get a pointer to the version object that corresponds to the instance's version.
+	targetVersion = std::dynamic_pointer_cast<MinecraftVersion>(ENV.getVersion("net.minecraft", m_inst->intendedVersionId()));
+	if (targetVersion == nullptr)
+	{
+		// don't do anything if it was invalid
+		emitFailed(tr("The specified Minecraft version is invalid. Choose a different one."));
+		return;
+	}
+	if (m_inst->providesVersionFile() || !targetVersion->needsUpdate())
+	{
+		qDebug() << "Instance either provides a version file or doesn't need an update.";
+		jarlibStart();
+		return;
+	}
+	versionUpdateTask = std::dynamic_pointer_cast<MinecraftVersionList>(ENV.getVersionList("net.minecraft"))->createUpdateTask(m_inst->intendedVersionId());
+	if (!versionUpdateTask)
+	{
+		qDebug() << "Didn't spawn an update task.";
+		jarlibStart();
+		return;
+	}
+	connect(versionUpdateTask.get(), SIGNAL(succeeded()), SLOT(jarlibStart()));
+	connect(versionUpdateTask.get(), &NetJob::failed, this, &OneSixUpdate::versionUpdateFailed);
+	connect(versionUpdateTask.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	setStatus(tr("Getting the version files from Mojang..."));
+	versionUpdateTask->start();
+}
+
+void OneSixUpdate::versionUpdateFailed(QString reason)
+{
+	emitFailed(reason);
+}
+
+void OneSixUpdate::assetIndexStart()
+{
+	setStatus(tr("Updating assets index..."));
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	auto profile = inst->getMinecraftProfile();
+	auto assets = profile->getMinecraftAssets();
+	QUrl indexUrl = assets->url;
+	QString localPath = assets->id + ".json";
+	auto job = new NetJob(tr("Asset index for %1").arg(inst->name()));
+
+	auto metacache = ENV.metacache();
+	auto entry = metacache->resolveEntry("asset_indexes", localPath);
+	entry->setStale(true);
+	job->addNetAction(CacheDownload::make(indexUrl, entry));
+	jarlibDownloadJob.reset(job);
+
+	connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(assetIndexFinished()));
+	connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::assetIndexFailed);
+	connect(jarlibDownloadJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+
+	qDebug() << m_inst->name() << ": Starting asset index download";
+	jarlibDownloadJob->start();
+}
+
+void OneSixUpdate::assetIndexFinished()
+{
+	AssetsIndex index;
+	qDebug() << m_inst->name() << ": Finished asset index download";
+
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	auto profile = inst->getMinecraftProfile();
+	auto assets = profile->getMinecraftAssets();
+
+	QString asset_fname = "assets/indexes/" + assets->id + ".json";
+	// FIXME: this looks like a job for a generic validator based on json schema?
+	if (!AssetsUtils::loadAssetsIndexJson(assets->id, asset_fname, &index))
+	{
+		auto metacache = ENV.metacache();
+		auto entry = metacache->resolveEntry("asset_indexes", assets->id + ".json");
+		metacache->evictEntry(entry);
+		emitFailed(tr("Failed to read the assets index!"));
+	}
+
+	auto job = index.getDownloadJob();
+	if(job)
+	{
+		setStatus(tr("Getting the assets files from Mojang..."));
+		jarlibDownloadJob = job;
+		connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(assetsFinished()));
+		connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::assetsFailed);
+		connect(jarlibDownloadJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+		jarlibDownloadJob->start();
+		return;
+	}
+	assetsFinished();
+}
+
+void OneSixUpdate::assetIndexFailed(QString reason)
+{
+	qDebug() << m_inst->name() << ": Failed asset index download";
+	emitFailed(tr("Failed to download the assets index:\n%1").arg(reason));
+}
+
+void OneSixUpdate::assetsFinished()
+{
+	emitSucceeded();
+}
+
+void OneSixUpdate::assetsFailed(QString reason)
+{
+	emitFailed(tr("Failed to download assets:\n%1").arg(reason));
+}
+
+void OneSixUpdate::jarlibStart()
+{
+	setStatus(tr("Getting the library files from Mojang..."));
+	qDebug() << m_inst->name() << ": downloading libraries";
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	inst->reloadProfile();
+	if(inst->flags() & BaseInstance::VersionBrokenFlag)
+	{
+		emitFailed(tr("Failed to load the version description files - check the instance for errors."));
+		return;
+	}
+
+	// Build a list of URLs that will need to be downloaded.
+	std::shared_ptr<MinecraftProfile> profile = inst->getMinecraftProfile();
+	// minecraft.jar for this version
+	{
+		QString version_id = profile->getMinecraftVersion();
+		QString localPath = version_id + "/" + version_id + ".jar";
+		QString urlstr = profile->getMainJarUrl();
+
+		auto job = new NetJob(tr("Libraries for instance %1").arg(inst->name()));
+
+		auto metacache = ENV.metacache();
+		auto entry = metacache->resolveEntry("versions", localPath);
+		job->addNetAction(CacheDownload::make(QUrl(urlstr), entry));
+		jarlibDownloadJob.reset(job);
+	}
+
+	auto libs = profile->getLibraries();
+
+	auto metacache = ENV.metacache();
+	QList<LibraryPtr> brokenLocalLibs;
+
+	QStringList failedFiles;
+	for (auto lib : libs)
+	{
+		auto dls = lib->getDownloads(currentSystem, metacache.get(), failedFiles);
+		for(auto dl : dls)
+		{
+			jarlibDownloadJob->addNetAction(dl);
+		}
+	}
+	if (!brokenLocalLibs.empty())
+	{
+		jarlibDownloadJob.reset();
+
+		QString failed_all = failedFiles.join("\n");
+		emitFailed(tr("Some libraries marked as 'local' are missing their jar "
+					  "files:\n%1\n\nYou'll have to correct this problem manually. If this is "
+					  "an externally tracked instance, make sure to run it at least once "
+					  "outside of MultiMC.").arg(failed_all));
+		return;
+	}
+
+	connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(jarlibFinished()));
+	connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::jarlibFailed);
+	connect(jarlibDownloadJob.get(), SIGNAL(progress(qint64, qint64)),
+			SIGNAL(progress(qint64, qint64)));
+
+	jarlibDownloadJob->start();
+}
+
+void OneSixUpdate::jarlibFinished()
+{
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	std::shared_ptr<MinecraftProfile> profile = inst->getMinecraftProfile();
+
+	if (profile->hasTrait("legacyFML"))
+	{
+		fmllibsStart();
+	}
+	else
+	{
+		assetIndexStart();
+	}
+}
+
+void OneSixUpdate::jarlibFailed(QString reason)
+{
+	QStringList failed = jarlibDownloadJob->getFailedFiles();
+	QString failed_all = failed.join("\n");
+	emitFailed(
+		tr("Failed to download the following files:\n%1\n\nReason:%2\nPlease try again.").arg(failed_all, reason));
+}
+
+void OneSixUpdate::fmllibsStart()
+{
+	// Get the mod list
+	OneSixInstance *inst = (OneSixInstance *)m_inst;
+	std::shared_ptr<MinecraftProfile> profile = inst->getMinecraftProfile();
+	bool forge_present = false;
+
+	QString version = inst->intendedVersionId();
+	auto &fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
+	if (!fmlLibsMapping.contains(version))
+	{
+		assetIndexStart();
+		return;
+	}
+
+	auto &libList = fmlLibsMapping[version];
+
+	// determine if we need some libs for FML or forge
+	setStatus(tr("Checking for FML libraries..."));
+	forge_present = (profile->versionPatch("net.minecraftforge") != nullptr);
+	// we don't...
+	if (!forge_present)
+	{
+		assetIndexStart();
+		return;
+	}
+
+	// now check the lib folder inside the instance for files.
+	for (auto &lib : libList)
+	{
+		QFileInfo libInfo(FS::PathCombine(inst->libDir(), lib.filename));
+		if (libInfo.exists())
+			continue;
+		fmlLibsToProcess.append(lib);
+	}
+
+	// if everything is in place, there's nothing to do here...
+	if (fmlLibsToProcess.isEmpty())
+	{
+		assetIndexStart();
+		return;
+	}
+
+	// download missing libs to our place
+	setStatus(tr("Dowloading FML libraries..."));
+	auto dljob = new NetJob("FML libraries");
+	auto metacache = ENV.metacache();
+	for (auto &lib : fmlLibsToProcess)
+	{
+		auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+		QString urlString = lib.ours ? URLConstants::FMLLIBS_OUR_BASE_URL + lib.filename
+									 : URLConstants::FMLLIBS_FORGE_BASE_URL + lib.filename;
+		dljob->addNetAction(CacheDownload::make(QUrl(urlString), entry));
+	}
+
+	connect(dljob, SIGNAL(succeeded()), SLOT(fmllibsFinished()));
+	connect(dljob, &NetJob::failed, this, &OneSixUpdate::fmllibsFailed);
+	connect(dljob, SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
+	legacyDownloadJob.reset(dljob);
+	legacyDownloadJob->start();
+}
+
+void OneSixUpdate::fmllibsFinished()
+{
+	legacyDownloadJob.reset();
+	if (!fmlLibsToProcess.isEmpty())
+	{
+		setStatus(tr("Copying FML libraries into the instance..."));
+		OneSixInstance *inst = (OneSixInstance *)m_inst;
+		auto metacache = ENV.metacache();
+		int index = 0;
+		for (auto &lib : fmlLibsToProcess)
+		{
+			progress(index, fmlLibsToProcess.size());
+			auto entry = metacache->resolveEntry("fmllibs", lib.filename);
+			auto path = FS::PathCombine(inst->libDir(), lib.filename);
+			if (!FS::ensureFilePathExists(path))
+			{
+				emitFailed(tr("Failed creating FML library folder inside the instance."));
+				return;
+			}
+			if (!QFile::copy(entry->getFullPath(), FS::PathCombine(inst->libDir(), lib.filename)))
+			{
+				emitFailed(tr("Failed copying Forge/FML library: %1.").arg(lib.filename));
+				return;
+			}
+			index++;
+		}
+		progress(index, fmlLibsToProcess.size());
+	}
+	assetIndexStart();
+}
+
+void OneSixUpdate::fmllibsFailed(QString reason)
+{
+	emitFailed(tr("Game update failed: it was impossible to fetch the required FML libraries.\nReason:\n%1").arg(reason));
+	return;
+}
+
diff --git a/libraries/logic/minecraft/onesix/OneSixUpdate.h b/libraries/logic/minecraft/onesix/OneSixUpdate.h
new file mode 100644
index 00000000..b5195364
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixUpdate.h
@@ -0,0 +1,67 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QList>
+#include <QUrl>
+
+#include "net/NetJob.h"
+#include "tasks/Task.h"
+#include "minecraft/VersionFilterData.h"
+#include <quazip.h>
+
+class MinecraftVersion;
+class OneSixInstance;
+
+class OneSixUpdate : public Task
+{
+	Q_OBJECT
+public:
+	explicit OneSixUpdate(OneSixInstance *inst, QObject *parent = 0);
+	virtual void executeTask();
+
+private
+slots:
+	void versionUpdateFailed(QString reason);
+
+	void jarlibStart();
+	void jarlibFinished();
+	void jarlibFailed(QString reason);
+
+	void fmllibsStart();
+	void fmllibsFinished();
+	void fmllibsFailed(QString reason);
+
+	void assetIndexStart();
+	void assetIndexFinished();
+	void assetIndexFailed(QString reason);
+
+	void assetsFinished();
+	void assetsFailed(QString reason);
+
+private:
+	NetJobPtr jarlibDownloadJob;
+	NetJobPtr legacyDownloadJob;
+
+	/// target version, determined during this task
+	std::shared_ptr<MinecraftVersion> targetVersion;
+	/// the task that is spawned for version updates
+	std::shared_ptr<Task> versionUpdateTask;
+
+	OneSixInstance *m_inst = nullptr;
+	QList<FMLlib> fmlLibsToProcess;
+};
diff --git a/libraries/logic/minecraft/onesix/OneSixVersionFormat.cpp b/libraries/logic/minecraft/onesix/OneSixVersionFormat.cpp
new file mode 100644
index 00000000..541fb109
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixVersionFormat.cpp
@@ -0,0 +1,225 @@
+#include "OneSixVersionFormat.h"
+#include <Json.h>
+#include "minecraft/ParseUtils.h"
+#include <minecraft/MinecraftVersion.h>
+#include <minecraft/VersionBuildError.h>
+#include <minecraft/MojangVersionFormat.h>
+
+using namespace Json;
+
+static void readString(const QJsonObject &root, const QString &key, QString &variable)
+{
+	if (root.contains(key))
+	{
+		variable = requireString(root.value(key));
+	}
+}
+
+LibraryPtr OneSixVersionFormat::libraryFromJson(const QJsonObject &libObj, const QString &filename)
+{
+	LibraryPtr out = MojangVersionFormat::libraryFromJson(libObj, filename);
+	readString(libObj, "MMC-hint", out->m_hint);
+	readString(libObj, "MMC-absulute_url", out->m_absoluteURL);
+	readString(libObj, "MMC-absoluteUrl", out->m_absoluteURL);
+	return out;
+}
+
+QJsonObject OneSixVersionFormat::libraryToJson(Library *library)
+{
+	QJsonObject libRoot = MojangVersionFormat::libraryToJson(library);
+	if (library->m_absoluteURL.size())
+		libRoot.insert("MMC-absoluteUrl", library->m_absoluteURL);
+	if (library->m_hint.size())
+		libRoot.insert("MMC-hint", library->m_hint);
+	return libRoot;
+}
+
+VersionFilePtr OneSixVersionFormat::versionFileFromJson(const QJsonDocument &doc, const QString &filename, const bool requireOrder)
+{
+	VersionFilePtr out(new VersionFile());
+	if (doc.isEmpty() || doc.isNull())
+	{
+		throw JSONValidationError(filename + " is empty or null");
+	}
+	if (!doc.isObject())
+	{
+		throw JSONValidationError(filename + " is not an object");
+	}
+
+	QJsonObject root = doc.object();
+
+	if (requireOrder)
+	{
+		if (root.contains("order"))
+		{
+			out->order = requireInteger(root.value("order"));
+		}
+		else
+		{
+			// FIXME: evaluate if we don't want to throw exceptions here instead
+			qCritical() << filename << "doesn't contain an order field";
+		}
+	}
+
+	out->name = root.value("name").toString();
+	out->fileId = root.value("fileId").toString();
+	out->version = root.value("version").toString();
+	out->dependsOnMinecraftVersion = root.value("mcVersion").toString();
+	out->filename = filename;
+
+	MojangVersionFormat::readVersionProperties(root, out.get());
+
+	// added for legacy Minecraft window embedding, TODO: remove
+	readString(root, "appletClass", out->appletClass);
+
+	if (root.contains("+tweakers"))
+	{
+		for (auto tweakerVal : requireArray(root.value("+tweakers")))
+		{
+			out->addTweakers.append(requireString(tweakerVal));
+		}
+	}
+
+	if (root.contains("+traits"))
+	{
+		for (auto tweakerVal : requireArray(root.value("+traits")))
+		{
+			out->traits.insert(requireString(tweakerVal));
+		}
+	}
+
+	if (root.contains("+jarMods"))
+	{
+		for (auto libVal : requireArray(root.value("+jarMods")))
+		{
+			QJsonObject libObj = requireObject(libVal);
+			// parse the jarmod
+			auto lib = OneSixVersionFormat::jarModFromJson(libObj, filename, out->name);
+			if(lib->originalName.isEmpty())
+			{
+				auto fixed = out->name;
+				fixed.remove(" (jar mod)");
+				lib->originalName = out->name;
+			}
+			// and add to jar mods
+			out->jarMods.append(lib);
+		}
+	}
+
+	auto readLibs = [&](const char * which)
+	{
+		for (auto libVal : requireArray(root.value(which)))
+		{
+			QJsonObject libObj = requireObject(libVal);
+			// parse the library
+			auto lib = libraryFromJson(libObj, filename);
+			out->libraries.append(lib);
+		}
+	};
+	bool hasPlusLibs = root.contains("+libraries");
+	bool hasLibs = root.contains("libraries");
+	if (hasPlusLibs && hasLibs)
+	{
+		out->addProblem(PROBLEM_WARNING, QObject::tr("Version file has both '+libraries' and 'libraries'. This is no longer supported."));
+		readLibs("libraries");
+		readLibs("+libraries");
+	}
+	else if (hasLibs)
+	{
+		readLibs("libraries");
+	}
+	else if(hasPlusLibs)
+	{
+		readLibs("+libraries");
+	}
+
+	/* removed features that shouldn't be used */
+	if (root.contains("tweakers"))
+	{
+		out->addProblem(PROBLEM_ERROR, QObject::tr("Version file contains unsupported element 'tweakers'"));
+	}
+	if (root.contains("-libraries"))
+	{
+		out->addProblem(PROBLEM_ERROR, QObject::tr("Version file contains unsupported element '-libraries'"));
+	}
+	if (root.contains("-tweakers"))
+	{
+		out->addProblem(PROBLEM_ERROR, QObject::tr("Version file contains unsupported element '-tweakers'"));
+	}
+	if (root.contains("-minecraftArguments"))
+	{
+		out->addProblem(PROBLEM_ERROR, QObject::tr("Version file contains unsupported element '-minecraftArguments'"));
+	}
+	if (root.contains("+minecraftArguments"))
+	{
+		out->addProblem(PROBLEM_ERROR, QObject::tr("Version file contains unsupported element '+minecraftArguments'"));
+	}
+	return out;
+}
+
+QJsonDocument OneSixVersionFormat::versionFileToJson(const VersionFilePtr &patch, bool saveOrder)
+{
+	QJsonObject root;
+	if (saveOrder)
+	{
+		root.insert("order", patch->order);
+	}
+	writeString(root, "name", patch->name);
+	writeString(root, "fileId", patch->fileId);
+	writeString(root, "version", patch->version);
+	writeString(root, "mcVersion", patch->dependsOnMinecraftVersion);
+
+	MojangVersionFormat::writeVersionProperties(patch.get(), root);
+
+	writeString(root, "appletClass", patch->appletClass);
+	writeStringList(root, "+tweakers", patch->addTweakers);
+	writeStringList(root, "+traits", patch->traits.toList());
+	if (!patch->libraries.isEmpty())
+	{
+		QJsonArray array;
+		for (auto value: patch->libraries)
+		{
+			array.append(OneSixVersionFormat::libraryToJson(value.get()));
+		}
+		root.insert("+libraries", array);
+	}
+	if (!patch->jarMods.isEmpty())
+	{
+		QJsonArray array;
+		for (auto value: patch->jarMods)
+		{
+			array.append(OneSixVersionFormat::jarModtoJson(value.get()));
+		}
+		root.insert("+jarMods", array);
+	}
+	// write the contents to a json document.
+	{
+		QJsonDocument out;
+		out.setObject(root);
+		return out;
+	}
+}
+
+JarmodPtr OneSixVersionFormat::jarModFromJson(const QJsonObject &libObj, const QString &filename, const QString &originalName)
+{
+	JarmodPtr out(new Jarmod());
+	if (!libObj.contains("name"))
+	{
+		throw JSONValidationError(filename +
+								  "contains a jarmod that doesn't have a 'name' field");
+	}
+	out->name = libObj.value("name").toString();
+	out->originalName = libObj.value("originalName").toString();
+	return out;
+}
+
+QJsonObject OneSixVersionFormat::jarModtoJson(Jarmod *jarmod)
+{
+	QJsonObject out;
+	writeString(out, "name", jarmod->name);
+	if(!jarmod->originalName.isEmpty())
+	{
+		writeString(out, "originalName", jarmod->originalName);
+	}
+	return out;
+}
diff --git a/libraries/logic/minecraft/onesix/OneSixVersionFormat.h b/libraries/logic/minecraft/onesix/OneSixVersionFormat.h
new file mode 100644
index 00000000..5696e79e
--- /dev/null
+++ b/libraries/logic/minecraft/onesix/OneSixVersionFormat.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <minecraft/VersionFile.h>
+#include <minecraft/MinecraftProfile.h>
+#include <minecraft/Library.h>
+#include <QJsonDocument>
+
+class OneSixVersionFormat
+{
+public:
+	// version files / profile patches
+	static VersionFilePtr versionFileFromJson(const QJsonDocument &doc, const QString &filename, const bool requireOrder);
+	static QJsonDocument versionFileToJson(const VersionFilePtr &patch, bool saveOrder);
+
+	// libraries
+	static LibraryPtr libraryFromJson(const QJsonObject &libObj, const QString &filename);
+	static QJsonObject libraryToJson(Library *library);
+
+	// jar mods
+	static JarmodPtr jarModFromJson(const QJsonObject &libObj, const QString &filename, const QString &originalName);
+	static QJsonObject jarModtoJson(Jarmod * jarmod);
+};
diff --git a/libraries/logic/net/ByteArrayDownload.cpp b/libraries/logic/net/ByteArrayDownload.cpp
new file mode 100644
index 00000000..21990eeb
--- /dev/null
+++ b/libraries/logic/net/ByteArrayDownload.cpp
@@ -0,0 +1,105 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ByteArrayDownload.h"
+#include "Env.h"
+#include <QDebug>
+
+ByteArrayDownload::ByteArrayDownload(QUrl url) : NetAction()
+{
+	m_url = url;
+	m_status = Job_NotStarted;
+}
+
+void ByteArrayDownload::start()
+{
+	qDebug() << "Downloading " << m_url.toString();
+	QNetworkRequest request(m_url);
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Uncached)");
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->get(request);
+
+	m_reply.reset(rep);
+	connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
+			SLOT(downloadProgress(qint64, qint64)));
+	connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
+			SLOT(downloadError(QNetworkReply::NetworkError)));
+	connect(rep, SIGNAL(readyRead()), SLOT(downloadReadyRead()));
+}
+
+void ByteArrayDownload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
+{
+	m_total_progress = bytesTotal;
+	m_progress = bytesReceived;
+	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
+}
+
+void ByteArrayDownload::downloadError(QNetworkReply::NetworkError error)
+{
+	// error happened during download.
+	qCritical() << "Error getting URL:" << m_url.toString().toLocal8Bit()
+				 << "Network error: " << error;
+	m_status = Job_Failed;
+	m_errorString = m_reply->errorString();
+}
+
+void ByteArrayDownload::downloadFinished()
+{
+	QVariant redirect = m_reply->header(QNetworkRequest::LocationHeader);
+	QString redirectURL;
+	if(redirect.isValid())
+	{
+		redirectURL = redirect.toString();
+	}
+	// FIXME: This is a hack for https://bugreports.qt-project.org/browse/QTBUG-41061
+	else if(m_reply->hasRawHeader("Location"))
+	{
+		auto data = m_reply->rawHeader("Location");
+		if(data.size() > 2 && data[0] == '/' && data[1] == '/')
+			redirectURL = m_reply->url().scheme() + ":" + data;
+	}
+	if (!redirectURL.isEmpty())
+	{
+		m_url = QUrl(redirect.toString());
+		qDebug() << "Following redirect to " << m_url.toString();
+		start();
+		return;
+	}
+
+	// if the download succeeded
+	if (m_status != Job_Failed)
+	{
+		// nothing went wrong...
+		m_status = Job_Finished;
+		m_data = m_reply->readAll();
+		m_content_type = m_reply->header(QNetworkRequest::ContentTypeHeader).toString();
+		m_reply.reset();
+		emit succeeded(m_index_within_job);
+		return;
+	}
+	// else the download failed
+	else
+	{
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		return;
+	}
+}
+
+void ByteArrayDownload::downloadReadyRead()
+{
+	// ~_~
+}
diff --git a/libraries/logic/net/ByteArrayDownload.h b/libraries/logic/net/ByteArrayDownload.h
new file mode 100644
index 00000000..e2fc2911
--- /dev/null
+++ b/libraries/logic/net/ByteArrayDownload.h
@@ -0,0 +1,48 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include "NetAction.h"
+
+#include "multimc_logic_export.h"
+
+typedef std::shared_ptr<class ByteArrayDownload> ByteArrayDownloadPtr;
+class MULTIMC_LOGIC_EXPORT ByteArrayDownload : public NetAction
+{
+	Q_OBJECT
+public:
+	ByteArrayDownload(QUrl url);
+	static ByteArrayDownloadPtr make(QUrl url)
+	{
+		return ByteArrayDownloadPtr(new ByteArrayDownload(url));
+	}
+    virtual ~ByteArrayDownload() {};
+public:
+	/// if not saving to file, downloaded data is placed here
+	QByteArray m_data;
+
+	QString m_errorString;
+
+public
+slots:
+	virtual void start();
+
+protected
+slots:
+	void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	void downloadError(QNetworkReply::NetworkError error);
+	void downloadFinished();
+	void downloadReadyRead();
+};
diff --git a/libraries/logic/net/CacheDownload.cpp b/libraries/logic/net/CacheDownload.cpp
new file mode 100644
index 00000000..1ac55180
--- /dev/null
+++ b/libraries/logic/net/CacheDownload.cpp
@@ -0,0 +1,192 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "CacheDownload.h"
+
+#include <QCryptographicHash>
+#include <QFileInfo>
+#include <QDateTime>
+#include <QDebug>
+#include "Env.h"
+#include <FileSystem.h>
+
+CacheDownload::CacheDownload(QUrl url, MetaEntryPtr entry)
+	: NetAction(), md5sum(QCryptographicHash::Md5)
+{
+	m_url = url;
+	m_entry = entry;
+	m_target_path = entry->getFullPath();
+	m_status = Job_NotStarted;
+}
+
+void CacheDownload::start()
+{
+	m_status = Job_InProgress;
+	if (!m_entry->isStale())
+	{
+		m_status = Job_Finished;
+		emit succeeded(m_index_within_job);
+		return;
+	}
+	// create a new save file
+	m_output_file.reset(new QSaveFile(m_target_path));
+
+	// if there already is a file and md5 checking is in effect and it can be opened
+	if (!FS::ensureFilePathExists(m_target_path))
+	{
+		qCritical() << "Could not create folder for " + m_target_path;
+		m_status = Job_Failed;
+		emit failed(m_index_within_job);
+		return;
+	}
+	if (!m_output_file->open(QIODevice::WriteOnly))
+	{
+		qCritical() << "Could not open " + m_target_path + " for writing";
+		m_status = Job_Failed;
+		emit failed(m_index_within_job);
+		return;
+	}
+	qDebug() << "Downloading " << m_url.toString();
+	QNetworkRequest request(m_url);
+
+	// check file consistency first.
+	QFile current(m_target_path);
+	if(current.exists() && current.size() != 0)
+	{
+		if (m_entry->getRemoteChangedTimestamp().size())
+			request.setRawHeader(QString("If-Modified-Since").toLatin1(),
+								m_entry->getRemoteChangedTimestamp().toLatin1());
+		if (m_entry->getETag().size())
+			request.setRawHeader(QString("If-None-Match").toLatin1(), m_entry->getETag().toLatin1());
+	}
+
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Cached)");
+
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->get(request);
+
+	m_reply.reset(rep);
+	connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
+			SLOT(downloadProgress(qint64, qint64)));
+	connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
+			SLOT(downloadError(QNetworkReply::NetworkError)));
+	connect(rep, SIGNAL(readyRead()), SLOT(downloadReadyRead()));
+}
+
+void CacheDownload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
+{
+	m_total_progress = bytesTotal;
+	m_progress = bytesReceived;
+	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
+}
+
+void CacheDownload::downloadError(QNetworkReply::NetworkError error)
+{
+	// error happened during download.
+	qCritical() << "Failed " << m_url.toString() << " with reason " << error;
+	m_status = Job_Failed;
+}
+void CacheDownload::downloadFinished()
+{
+	QVariant redirect = m_reply->header(QNetworkRequest::LocationHeader);
+	QString redirectURL;
+	if(redirect.isValid())
+	{
+		redirectURL = redirect.toString();
+	}
+	// FIXME: This is a hack for https://bugreports.qt-project.org/browse/QTBUG-41061
+	else if(m_reply->hasRawHeader("Location"))
+	{
+		auto data = m_reply->rawHeader("Location");
+		if(data.size() > 2 && data[0] == '/' && data[1] == '/')
+			redirectURL = m_reply->url().scheme() + ":" + data;
+	}
+	if (!redirectURL.isEmpty())
+	{
+		m_url = QUrl(redirect.toString());
+		qDebug() << "Following redirect to " << m_url.toString();
+		start();
+		return;
+	}
+
+	// if the download succeeded
+	if (m_status == Job_Failed)
+	{
+		m_output_file->cancelWriting();
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		return;
+	}
+
+	// if we wrote any data to the save file, we try to commit the data to the real file.
+	if (wroteAnyData)
+	{
+		// nothing went wrong...
+		if (m_output_file->commit())
+		{
+			m_status = Job_Finished;
+			m_entry->setMD5Sum(md5sum.result().toHex().constData());
+		}
+		else
+		{
+			qCritical() << "Failed to commit changes to " << m_target_path;
+			m_output_file->cancelWriting();
+			m_reply.reset();
+			m_status = Job_Failed;
+			emit failed(m_index_within_job);
+			return;
+		}
+	}
+	else
+	{
+		m_status = Job_Finished;
+	}
+
+	// then get rid of the save file
+	m_output_file.reset();
+
+	QFileInfo output_file_info(m_target_path);
+
+	m_entry->setETag(m_reply->rawHeader("ETag").constData());
+	if (m_reply->hasRawHeader("Last-Modified"))
+	{
+		m_entry->setRemoteChangedTimestamp(m_reply->rawHeader("Last-Modified").constData());
+	}
+	m_entry->setLocalChangedTimestamp(output_file_info.lastModified().toUTC().toMSecsSinceEpoch());
+	m_entry->setStale(false);
+	ENV.metacache()->updateEntry(m_entry);
+
+	m_reply.reset();
+	emit succeeded(m_index_within_job);
+	return;
+}
+
+void CacheDownload::downloadReadyRead()
+{
+	QByteArray ba = m_reply->readAll();
+	md5sum.addData(ba);
+	if (m_output_file->write(ba) != ba.size())
+	{
+		qCritical() << "Failed writing into " + m_target_path;
+		m_status = Job_Failed;
+		m_output_file->cancelWriting();
+		m_output_file.reset();
+		emit failed(m_index_within_job);
+		wroteAnyData = false;
+		return;
+	}
+	wroteAnyData = true;
+}
diff --git a/libraries/logic/net/CacheDownload.h b/libraries/logic/net/CacheDownload.h
new file mode 100644
index 00000000..d83b2a0f
--- /dev/null
+++ b/libraries/logic/net/CacheDownload.h
@@ -0,0 +1,63 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "NetAction.h"
+#include "HttpMetaCache.h"
+#include <QCryptographicHash>
+#include <QSaveFile>
+
+#include "multimc_logic_export.h"
+
+typedef std::shared_ptr<class CacheDownload> CacheDownloadPtr;
+class MULTIMC_LOGIC_EXPORT CacheDownload : public NetAction
+{
+	Q_OBJECT
+private:
+	MetaEntryPtr m_entry;
+	/// if saving to file, use the one specified in this string
+	QString m_target_path;
+
+	/// this is the output file, if any
+	std::unique_ptr<QSaveFile> m_output_file;
+
+	/// the hash-as-you-download
+	QCryptographicHash md5sum;
+
+	bool wroteAnyData = false;
+
+public:
+	explicit CacheDownload(QUrl url, MetaEntryPtr entry);
+	static CacheDownloadPtr make(QUrl url, MetaEntryPtr entry)
+	{
+		return CacheDownloadPtr(new CacheDownload(url, entry));
+	}
+	virtual ~CacheDownload(){};
+	QString getTargetFilepath()
+	{
+		return m_target_path;
+	}
+protected
+slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	virtual void downloadError(QNetworkReply::NetworkError error);
+	virtual void downloadFinished();
+	virtual void downloadReadyRead();
+
+public
+slots:
+	virtual void start();
+};
diff --git a/libraries/logic/net/HttpMetaCache.cpp b/libraries/logic/net/HttpMetaCache.cpp
new file mode 100644
index 00000000..ea3e2834
--- /dev/null
+++ b/libraries/logic/net/HttpMetaCache.cpp
@@ -0,0 +1,273 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Env.h"
+#include "HttpMetaCache.h"
+#include "FileSystem.h"
+
+#include <QFileInfo>
+#include <QFile>
+#include <QDateTime>
+#include <QCryptographicHash>
+
+#include <QDebug>
+
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QJsonObject>
+
+QString MetaEntry::getFullPath()
+{
+	// FIXME: make local?
+	return FS::PathCombine(basePath, relativePath);
+}
+
+HttpMetaCache::HttpMetaCache(QString path) : QObject()
+{
+	m_index_file = path;
+	saveBatchingTimer.setSingleShot(true);
+	saveBatchingTimer.setTimerType(Qt::VeryCoarseTimer);
+	connect(&saveBatchingTimer, SIGNAL(timeout()), SLOT(SaveNow()));
+}
+
+HttpMetaCache::~HttpMetaCache()
+{
+	saveBatchingTimer.stop();
+	SaveNow();
+}
+
+MetaEntryPtr HttpMetaCache::getEntry(QString base, QString resource_path)
+{
+	// no base. no base path. can't store
+	if (!m_entries.contains(base))
+	{
+		// TODO: log problem
+		return MetaEntryPtr();
+	}
+	EntryMap &map = m_entries[base];
+	if (map.entry_list.contains(resource_path))
+	{
+		return map.entry_list[resource_path];
+	}
+	return MetaEntryPtr();
+}
+
+MetaEntryPtr HttpMetaCache::resolveEntry(QString base, QString resource_path, QString expected_etag)
+{
+	auto entry = getEntry(base, resource_path);
+	// it's not present? generate a default stale entry
+	if (!entry)
+	{
+		return staleEntry(base, resource_path);
+	}
+
+	auto &selected_base = m_entries[base];
+	QString real_path = FS::PathCombine(selected_base.base_path, resource_path);
+	QFileInfo finfo(real_path);
+
+	// is the file really there? if not -> stale
+	if (!finfo.isFile() || !finfo.isReadable())
+	{
+		// if the file doesn't exist, we disown the entry
+		selected_base.entry_list.remove(resource_path);
+		return staleEntry(base, resource_path);
+	}
+
+	if (!expected_etag.isEmpty() && expected_etag != entry->etag)
+	{
+		// if the etag doesn't match expected, we disown the entry
+		selected_base.entry_list.remove(resource_path);
+		return staleEntry(base, resource_path);
+	}
+
+	// if the file changed, check md5sum
+	qint64 file_last_changed = finfo.lastModified().toUTC().toMSecsSinceEpoch();
+	if (file_last_changed != entry->local_changed_timestamp)
+	{
+		QFile input(real_path);
+		input.open(QIODevice::ReadOnly);
+		QString md5sum = QCryptographicHash::hash(input.readAll(), QCryptographicHash::Md5)
+							 .toHex()
+							 .constData();
+		if (entry->md5sum != md5sum)
+		{
+			selected_base.entry_list.remove(resource_path);
+			return staleEntry(base, resource_path);
+		}
+		// md5sums matched... keep entry and save the new state to file
+		entry->local_changed_timestamp = file_last_changed;
+		SaveEventually();
+	}
+
+	// entry passed all the checks we cared about.
+	entry->basePath = getBasePath(base);
+	return entry;
+}
+
+bool HttpMetaCache::updateEntry(MetaEntryPtr stale_entry)
+{
+	if (!m_entries.contains(stale_entry->baseId))
+	{
+		qCritical() << "Cannot add entry with unknown base: "
+					 << stale_entry->baseId.toLocal8Bit();
+		return false;
+	}
+	if (stale_entry->stale)
+	{
+		qCritical() << "Cannot add stale entry: " << stale_entry->getFullPath().toLocal8Bit();
+		return false;
+	}
+	m_entries[stale_entry->baseId].entry_list[stale_entry->relativePath] = stale_entry;
+	SaveEventually();
+	return true;
+}
+
+bool HttpMetaCache::evictEntry(MetaEntryPtr entry)
+{
+	if(entry)
+	{
+		entry->stale = true;
+		SaveEventually();
+		return true;
+	}
+	return false;
+}
+
+MetaEntryPtr HttpMetaCache::staleEntry(QString base, QString resource_path)
+{
+	auto foo = new MetaEntry();
+	foo->baseId = base;
+	foo->basePath = getBasePath(base);
+	foo->relativePath = resource_path;
+	foo->stale = true;
+	return MetaEntryPtr(foo);
+}
+
+void HttpMetaCache::addBase(QString base, QString base_root)
+{
+	// TODO: report error
+	if (m_entries.contains(base))
+		return;
+	// TODO: check if the base path is valid
+	EntryMap foo;
+	foo.base_path = base_root;
+	m_entries[base] = foo;
+}
+
+QString HttpMetaCache::getBasePath(QString base)
+{
+	if (m_entries.contains(base))
+	{
+		return m_entries[base].base_path;
+	}
+	return QString();
+}
+
+void HttpMetaCache::Load()
+{
+	if(m_index_file.isNull())
+		return;
+
+	QFile index(m_index_file);
+	if (!index.open(QIODevice::ReadOnly))
+		return;
+
+	QJsonDocument json = QJsonDocument::fromJson(index.readAll());
+	if (!json.isObject())
+		return;
+	auto root = json.object();
+	// check file version first
+	auto version_val = root.value("version");
+	if (!version_val.isString())
+		return;
+	if (version_val.toString() != "1")
+		return;
+
+	// read the entry array
+	auto entries_val = root.value("entries");
+	if (!entries_val.isArray())
+		return;
+	QJsonArray array = entries_val.toArray();
+	for (auto element : array)
+	{
+		if (!element.isObject())
+			return;
+		auto element_obj = element.toObject();
+		QString base = element_obj.value("base").toString();
+		if (!m_entries.contains(base))
+			continue;
+		auto &entrymap = m_entries[base];
+		auto foo = new MetaEntry();
+		foo->baseId = base;
+		QString path = foo->relativePath = element_obj.value("path").toString();
+		foo->md5sum = element_obj.value("md5sum").toString();
+		foo->etag = element_obj.value("etag").toString();
+		foo->local_changed_timestamp = element_obj.value("last_changed_timestamp").toDouble();
+		foo->remote_changed_timestamp =
+			element_obj.value("remote_changed_timestamp").toString();
+		// presumed innocent until closer examination
+		foo->stale = false;
+		entrymap.entry_list[path] = MetaEntryPtr(foo);
+	}
+}
+
+void HttpMetaCache::SaveEventually()
+{
+	// reset the save timer
+	saveBatchingTimer.stop();
+	saveBatchingTimer.start(30000);
+}
+
+void HttpMetaCache::SaveNow()
+{
+	if(m_index_file.isNull())
+		return;
+	QJsonObject toplevel;
+	toplevel.insert("version", QJsonValue(QString("1")));
+	QJsonArray entriesArr;
+	for (auto group : m_entries)
+	{
+		for (auto entry : group.entry_list)
+		{
+			// do not save stale entries. they are dead.
+			if(entry->stale)
+			{
+				continue;
+			}
+			QJsonObject entryObj;
+			entryObj.insert("base", QJsonValue(entry->baseId));
+			entryObj.insert("path", QJsonValue(entry->relativePath));
+			entryObj.insert("md5sum", QJsonValue(entry->md5sum));
+			entryObj.insert("etag", QJsonValue(entry->etag));
+			entryObj.insert("last_changed_timestamp",
+							QJsonValue(double(entry->local_changed_timestamp)));
+			if (!entry->remote_changed_timestamp.isEmpty())
+				entryObj.insert("remote_changed_timestamp",
+								QJsonValue(entry->remote_changed_timestamp));
+			entriesArr.append(entryObj);
+		}
+	}
+	toplevel.insert("entries", entriesArr);
+
+	QJsonDocument doc(toplevel);
+	try
+	{
+		FS::write(m_index_file, doc.toJson());
+	}
+	catch (Exception & e)
+	{
+		qWarning() << e.what();
+	}
+}
diff --git a/libraries/logic/net/HttpMetaCache.h b/libraries/logic/net/HttpMetaCache.h
new file mode 100644
index 00000000..7b626c70
--- /dev/null
+++ b/libraries/logic/net/HttpMetaCache.h
@@ -0,0 +1,125 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QString>
+#include <QMap>
+#include <qtimer.h>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class HttpMetaCache;
+
+class MULTIMC_LOGIC_EXPORT MetaEntry
+{
+friend class HttpMetaCache;
+protected:
+	MetaEntry() {}
+public:
+	bool isStale()
+	{
+		return stale;
+	}
+	void setStale(bool stale)
+	{
+		this->stale = stale;
+	}
+	QString getFullPath();
+	QString getRemoteChangedTimestamp()
+	{
+		return remote_changed_timestamp;
+	}
+	void setRemoteChangedTimestamp(QString remote_changed_timestamp)
+	{
+		this->remote_changed_timestamp = remote_changed_timestamp;
+	}
+	void setLocalChangedTimestamp(qint64 timestamp)
+	{
+		local_changed_timestamp = timestamp;
+	}
+	QString getETag()
+	{
+		return etag;
+	}
+	void setETag(QString etag)
+	{
+		this->etag = etag;
+	}
+	QString getMD5Sum()
+	{
+		return md5sum;
+	}
+	void setMD5Sum(QString md5sum)
+	{
+		this->md5sum = md5sum;
+	}
+protected:
+	QString baseId;
+	QString basePath;
+	QString relativePath;
+	QString md5sum;
+	QString etag;
+	qint64 local_changed_timestamp = 0;
+	QString remote_changed_timestamp; // QString for now, RFC 2822 encoded time
+	bool stale = true;
+};
+
+typedef std::shared_ptr<MetaEntry> MetaEntryPtr;
+
+class MULTIMC_LOGIC_EXPORT HttpMetaCache : public QObject
+{
+	Q_OBJECT
+public:
+	// supply path to the cache index file
+	HttpMetaCache(QString path = QString());
+	~HttpMetaCache();
+
+	// get the entry solely from the cache
+	// you probably don't want this, unless you have some specific caching needs.
+	MetaEntryPtr getEntry(QString base, QString resource_path);
+
+	// get the entry from cache and verify that it isn't stale (within reason)
+	MetaEntryPtr resolveEntry(QString base, QString resource_path,
+							  QString expected_etag = QString());
+
+	// add a previously resolved stale entry
+	bool updateEntry(MetaEntryPtr stale_entry);
+
+	// evict selected entry from cache
+	bool evictEntry(MetaEntryPtr entry);
+
+	void addBase(QString base, QString base_root);
+
+	// (re)start a timer that calls SaveNow later.
+	void SaveEventually();
+	void Load();
+	QString getBasePath(QString base);
+public
+slots:
+	void SaveNow();
+
+private:
+	// create a new stale entry, given the parameters
+	MetaEntryPtr staleEntry(QString base, QString resource_path);
+	struct EntryMap
+	{
+		QString base_path;
+		QMap<QString, MetaEntryPtr> entry_list;
+	};
+	QMap<QString, EntryMap> m_entries;
+	QString m_index_file;
+	QTimer saveBatchingTimer;
+};
diff --git a/libraries/logic/net/MD5EtagDownload.cpp b/libraries/logic/net/MD5EtagDownload.cpp
new file mode 100644
index 00000000..3b4d5dcd
--- /dev/null
+++ b/libraries/logic/net/MD5EtagDownload.cpp
@@ -0,0 +1,155 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Env.h"
+#include "MD5EtagDownload.h"
+#include <FileSystem.h>
+#include <QCryptographicHash>
+#include <QDebug>
+
+MD5EtagDownload::MD5EtagDownload(QUrl url, QString target_path) : NetAction()
+{
+	m_url = url;
+	m_target_path = target_path;
+	m_status = Job_NotStarted;
+}
+
+void MD5EtagDownload::start()
+{
+	QString filename = m_target_path;
+	m_output_file.setFileName(filename);
+	// if there already is a file and md5 checking is in effect and it can be opened
+	if (m_output_file.exists() && m_output_file.open(QIODevice::ReadOnly))
+	{
+		// get the md5 of the local file.
+		m_local_md5 =
+			QCryptographicHash::hash(m_output_file.readAll(), QCryptographicHash::Md5)
+				.toHex()
+				.constData();
+		m_output_file.close();
+		// if we are expecting some md5sum, compare it with the local one
+		if (!m_expected_md5.isEmpty())
+		{
+			// skip if they match
+			if(m_local_md5 == m_expected_md5)
+			{
+				qDebug() << "Skipping " << m_url.toString() << ": md5 match.";
+				emit succeeded(m_index_within_job);
+				return;
+			}
+		}
+		else
+		{
+			// no expected md5. we use the local md5sum as an ETag
+		}
+	}
+	if (!FS::ensureFilePathExists(filename))
+	{
+		emit failed(m_index_within_job);
+		return;
+	}
+
+	QNetworkRequest request(m_url);
+
+	qDebug() << "Downloading " << m_url.toString() << " local MD5: " << m_local_md5;
+
+	if(!m_local_md5.isEmpty())
+	{
+		request.setRawHeader(QString("If-None-Match").toLatin1(), m_local_md5.toLatin1());
+	}
+	if(!m_expected_md5.isEmpty())
+		qDebug() << "Expecting " << m_expected_md5;
+
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Uncached)");
+
+	// Go ahead and try to open the file.
+	// If we don't do this, empty files won't be created, which breaks the updater.
+	// Plus, this way, we don't end up starting a download for a file we can't open.
+	if (!m_output_file.open(QIODevice::WriteOnly))
+	{
+		emit failed(m_index_within_job);
+		return;
+	}
+
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->get(request);
+
+	m_reply.reset(rep);
+	connect(rep, SIGNAL(downloadProgress(qint64, qint64)),
+			SLOT(downloadProgress(qint64, qint64)));
+	connect(rep, SIGNAL(finished()), SLOT(downloadFinished()));
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
+			SLOT(downloadError(QNetworkReply::NetworkError)));
+	connect(rep, SIGNAL(readyRead()), SLOT(downloadReadyRead()));
+}
+
+void MD5EtagDownload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
+{
+	m_total_progress = bytesTotal;
+	m_progress = bytesReceived;
+	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
+}
+
+void MD5EtagDownload::downloadError(QNetworkReply::NetworkError error)
+{
+	qCritical() << "Error" << error << ":" << m_reply->errorString() << "while downloading"
+				 << m_reply->url();
+	m_status = Job_Failed;
+}
+
+void MD5EtagDownload::downloadFinished()
+{
+	// if the download succeeded
+	if (m_status != Job_Failed)
+	{
+		// nothing went wrong...
+		m_status = Job_Finished;
+		m_output_file.close();
+
+		// FIXME: compare with the real written data md5sum
+		// this is just an ETag
+		qDebug() << "Finished " << m_url.toString() << " got " << m_reply->rawHeader("ETag").constData();
+
+		m_reply.reset();
+		emit succeeded(m_index_within_job);
+		return;
+	}
+	// else the download failed
+	else
+	{
+		m_output_file.close();
+		m_output_file.remove();
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		return;
+	}
+}
+
+void MD5EtagDownload::downloadReadyRead()
+{
+	if (!m_output_file.isOpen())
+	{
+		if (!m_output_file.open(QIODevice::WriteOnly))
+		{
+			/*
+			* Can't open the file... the job failed
+			*/
+			m_reply->abort();
+			emit failed(m_index_within_job);
+			return;
+		}
+	}
+	m_output_file.write(m_reply->readAll());
+}
diff --git a/libraries/logic/net/MD5EtagDownload.h b/libraries/logic/net/MD5EtagDownload.h
new file mode 100644
index 00000000..cd1cb550
--- /dev/null
+++ b/libraries/logic/net/MD5EtagDownload.h
@@ -0,0 +1,52 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "NetAction.h"
+#include <QFile>
+
+typedef std::shared_ptr<class MD5EtagDownload> Md5EtagDownloadPtr;
+class MD5EtagDownload : public NetAction
+{
+	Q_OBJECT
+public:
+	/// the expected md5 checksum. Only set from outside
+	QString m_expected_md5;
+	/// the md5 checksum of a file that already exists.
+	QString m_local_md5;
+	/// if saving to file, use the one specified in this string
+	QString m_target_path;
+	/// this is the output file, if any
+	QFile m_output_file;
+
+public:
+	explicit MD5EtagDownload(QUrl url, QString target_path);
+	static Md5EtagDownloadPtr make(QUrl url, QString target_path)
+	{
+		return Md5EtagDownloadPtr(new MD5EtagDownload(url, target_path));
+	}
+	virtual ~MD5EtagDownload(){};
+protected
+slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	virtual void downloadError(QNetworkReply::NetworkError error);
+	virtual void downloadFinished();
+	virtual void downloadReadyRead();
+
+public
+slots:
+	virtual void start();
+};
diff --git a/libraries/logic/net/NetAction.h b/libraries/logic/net/NetAction.h
new file mode 100644
index 00000000..3c395605
--- /dev/null
+++ b/libraries/logic/net/NetAction.h
@@ -0,0 +1,96 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QUrl>
+#include <memory>
+#include <QNetworkReply>
+#include <QObjectPtr.h>
+
+#include "multimc_logic_export.h"
+
+enum JobStatus
+{
+	Job_NotStarted,
+	Job_InProgress,
+	Job_Finished,
+	Job_Failed
+};
+
+typedef std::shared_ptr<class NetAction> NetActionPtr;
+class MULTIMC_LOGIC_EXPORT NetAction : public QObject
+{
+	Q_OBJECT
+protected:
+	explicit NetAction() : QObject(0) {};
+
+public:
+	virtual ~NetAction() {};
+
+public:
+	virtual qint64 totalProgress() const
+	{
+		return m_total_progress;
+	}
+	virtual qint64 currentProgress() const
+	{
+		return m_progress;
+	}
+	virtual qint64 numberOfFailures() const
+	{
+		return m_failures;
+	}
+
+public:
+	/// the network reply
+	unique_qobject_ptr<QNetworkReply> m_reply;
+
+	/// the content of the content-type header
+	QString m_content_type;
+
+	/// source URL
+	QUrl m_url;
+
+	/// The file's status
+	JobStatus m_status = Job_NotStarted;
+
+	/// index within the parent job
+	int m_index_within_job = 0;
+
+	qint64 m_progress = 0;
+	qint64 m_total_progress = 1;
+
+	/// number of failures up to this point
+	int m_failures = 0;
+
+signals:
+	void started(int index);
+	void netActionProgress(int index, qint64 current, qint64 total);
+	void succeeded(int index);
+	void failed(int index);
+
+protected
+slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal) = 0;
+	virtual void downloadError(QNetworkReply::NetworkError error) = 0;
+	virtual void downloadFinished() = 0;
+	virtual void downloadReadyRead() = 0;
+
+public
+slots:
+	virtual void start() = 0;
+};
diff --git a/libraries/logic/net/NetJob.cpp b/libraries/logic/net/NetJob.cpp
new file mode 100644
index 00000000..76c61c35
--- /dev/null
+++ b/libraries/logic/net/NetJob.cpp
@@ -0,0 +1,125 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "NetJob.h"
+#include "MD5EtagDownload.h"
+#include "ByteArrayDownload.h"
+#include "CacheDownload.h"
+
+#include <QDebug>
+
+void NetJob::partSucceeded(int index)
+{
+	// do progress. all slots are 1 in size at least
+	auto &slot = parts_progress[index];
+	partProgress(index, slot.total_progress, slot.total_progress);
+
+	m_doing.remove(index);
+	m_done.insert(index);
+	downloads[index].get()->disconnect(this);
+	startMoreParts();
+}
+
+void NetJob::partFailed(int index)
+{
+	m_doing.remove(index);
+	auto &slot = parts_progress[index];
+	if (slot.failures == 3)
+	{
+		m_failed.insert(index);
+	}
+	else
+	{
+		slot.failures++;
+		m_todo.enqueue(index);
+	}
+	downloads[index].get()->disconnect(this);
+	startMoreParts();
+}
+
+void NetJob::partProgress(int index, qint64 bytesReceived, qint64 bytesTotal)
+{
+	auto &slot = parts_progress[index];
+
+	current_progress -= slot.current_progress;
+	slot.current_progress = bytesReceived;
+	current_progress += slot.current_progress;
+
+	total_progress -= slot.total_progress;
+	slot.total_progress = bytesTotal;
+	total_progress += slot.total_progress;
+	setProgress(current_progress, total_progress);
+}
+
+void NetJob::executeTask()
+{
+	qDebug() << m_job_name.toLocal8Bit() << " started.";
+	m_running = true;
+	for (int i = 0; i < downloads.size(); i++)
+	{
+		m_todo.enqueue(i);
+	}
+	// hack that delays early failures so they can be caught easier
+	QMetaObject::invokeMethod(this, "startMoreParts", Qt::QueuedConnection);
+}
+
+void NetJob::startMoreParts()
+{
+	// check for final conditions if there's nothing in the queue
+	if(!m_todo.size())
+	{
+		if(!m_doing.size())
+		{
+			if(!m_failed.size())
+			{
+				qDebug() << m_job_name << "succeeded.";
+				emitSucceeded();
+			}
+			else
+			{
+				qCritical() << m_job_name << "failed.";
+				emitFailed(tr("Job '%1' failed to process:\n%2").arg(m_job_name).arg(getFailedFiles().join("\n")));
+			}
+		}
+		return;
+	}
+	// otherwise try to start more parts
+	while (m_doing.size() < 6)
+	{
+		if(!m_todo.size())
+			return;
+		int doThis = m_todo.dequeue();
+		m_doing.insert(doThis);
+		auto part = downloads[doThis];
+		// connect signals :D
+		connect(part.get(), SIGNAL(succeeded(int)), SLOT(partSucceeded(int)));
+		connect(part.get(), SIGNAL(failed(int)), SLOT(partFailed(int)));
+		connect(part.get(), SIGNAL(netActionProgress(int, qint64, qint64)),
+				SLOT(partProgress(int, qint64, qint64)));
+		part->start();
+	}
+}
+
+
+QStringList NetJob::getFailedFiles()
+{
+	QStringList failed;
+	for (auto index: m_failed)
+	{
+		failed.push_back(downloads[index]->m_url.toString());
+	}
+	failed.sort();
+	return failed;
+}
diff --git a/libraries/logic/net/NetJob.h b/libraries/logic/net/NetJob.h
new file mode 100644
index 00000000..167fe176
--- /dev/null
+++ b/libraries/logic/net/NetJob.h
@@ -0,0 +1,117 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <QtNetwork>
+#include "NetAction.h"
+#include "ByteArrayDownload.h"
+#include "MD5EtagDownload.h"
+#include "CacheDownload.h"
+#include "HttpMetaCache.h"
+#include "tasks/Task.h"
+#include "QObjectPtr.h"
+
+#include "multimc_logic_export.h"
+
+class NetJob;
+typedef shared_qobject_ptr<NetJob> NetJobPtr;
+
+class MULTIMC_LOGIC_EXPORT NetJob : public Task
+{
+	Q_OBJECT
+public:
+	explicit NetJob(QString job_name) : Task(), m_job_name(job_name) {}
+	virtual ~NetJob() {}
+	bool addNetAction(NetActionPtr action)
+	{
+		action->m_index_within_job = downloads.size();
+		downloads.append(action);
+		part_info pi;
+		{
+			pi.current_progress = action->currentProgress();
+			pi.total_progress = action->totalProgress();
+			pi.failures = action->numberOfFailures();
+		}
+		parts_progress.append(pi);
+		total_progress += pi.total_progress;
+		// if this is already running, the action needs to be started right away!
+		if (isRunning())
+		{
+			setProgress(current_progress, total_progress);
+			connect(action.get(), SIGNAL(succeeded(int)), SLOT(partSucceeded(int)));
+			connect(action.get(), SIGNAL(failed(int)), SLOT(partFailed(int)));
+			connect(action.get(), SIGNAL(netActionProgress(int, qint64, qint64)),
+					SLOT(partProgress(int, qint64, qint64)));
+			action->start();
+		}
+		return true;
+	}
+
+	NetActionPtr operator[](int index)
+	{
+		return downloads[index];
+	}
+	const NetActionPtr at(const int index)
+	{
+		return downloads.at(index);
+	}
+	NetActionPtr first()
+	{
+		if (downloads.size())
+			return downloads[0];
+		return NetActionPtr();
+	}
+	int size() const
+	{
+		return downloads.size();
+	}
+	virtual bool isRunning() const
+	{
+		return m_running;
+	}
+	QStringList getFailedFiles();
+
+private slots:
+	void startMoreParts();
+
+public slots:
+	virtual void executeTask();
+	// FIXME: implement
+	virtual bool abort() {return false;};
+
+private slots:
+	void partProgress(int index, qint64 bytesReceived, qint64 bytesTotal);
+	void partSucceeded(int index);
+	void partFailed(int index);
+
+private:
+	struct part_info
+	{
+		qint64 current_progress = 0;
+		qint64 total_progress = 1;
+		int failures = 0;
+		bool connected = false;
+	};
+	QString m_job_name;
+	QList<NetActionPtr> downloads;
+	QList<part_info> parts_progress;
+	QQueue<int> m_todo;
+	QSet<int> m_doing;
+	QSet<int> m_done;
+	QSet<int> m_failed;
+	qint64 current_progress = 0;
+	qint64 total_progress = 0;
+	bool m_running = false;
+};
diff --git a/libraries/logic/net/PasteUpload.cpp b/libraries/logic/net/PasteUpload.cpp
new file mode 100644
index 00000000..4b671d6f
--- /dev/null
+++ b/libraries/logic/net/PasteUpload.cpp
@@ -0,0 +1,99 @@
+#include "PasteUpload.h"
+#include "Env.h"
+#include <QDebug>
+#include <QJsonObject>
+#include <QJsonDocument>
+
+PasteUpload::PasteUpload(QWidget *window, QString text, QString key) : m_window(window)
+{
+	m_key = key;
+	QByteArray temp;
+	temp = text.toUtf8();
+	temp.replace('\n', "\r\n");
+	m_textSize = temp.size();
+	m_text = "key=" + m_key.toLatin1() + "&description=MultiMC5+Log+File&language=plain&format=json&expire=2592000&paste=" + temp.toPercentEncoding();
+	buf =  new QBuffer(&m_text);
+}
+
+PasteUpload::~PasteUpload()
+{
+	if(buf)
+	{
+		delete buf;
+	}
+}
+
+bool PasteUpload::validateText()
+{
+	return m_textSize <= maxSize();
+}
+
+void PasteUpload::executeTask()
+{
+	QNetworkRequest request(QUrl("http://paste.ee/api"));
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Uncached)");
+
+	request.setRawHeader("Content-Type", "application/x-www-form-urlencoded");
+	request.setRawHeader("Content-Length", QByteArray::number(m_text.size()));
+
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->post(request, buf);
+
+	m_reply = std::shared_ptr<QNetworkReply>(rep);
+	setStatus(tr("Uploading to paste.ee"));
+	connect(rep, &QNetworkReply::uploadProgress, this, &Task::setProgress);
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(downloadError(QNetworkReply::NetworkError)));
+	connect(rep, SIGNAL(finished()), this, SLOT(downloadFinished()));
+}
+
+void PasteUpload::downloadError(QNetworkReply::NetworkError error)
+{
+	// error happened during download.
+	qCritical() << "Network error: " << error;
+	emitFailed(m_reply->errorString());
+}
+
+void PasteUpload::downloadFinished()
+{
+	// if the download succeeded
+	if (m_reply->error() == QNetworkReply::NetworkError::NoError)
+	{
+		QByteArray data = m_reply->readAll();
+		m_reply.reset();
+		QJsonParseError jsonError;
+		QJsonDocument doc = QJsonDocument::fromJson(data, &jsonError);
+		if (jsonError.error != QJsonParseError::NoError)
+		{
+			emitFailed(jsonError.errorString());
+			return;
+		}
+		if (!parseResult(doc))
+		{
+			emitFailed(tr("paste.ee returned an error. Please consult the logs for more information"));
+			return;
+		}
+	}
+	// else the download failed
+	else
+	{
+		emitFailed(QString("Network error: %1").arg(m_reply->errorString()));
+		m_reply.reset();
+		return;
+	}
+	emitSucceeded();
+}
+
+bool PasteUpload::parseResult(QJsonDocument doc)
+{
+	auto object = doc.object();
+	auto status = object.value("status").toString("error");
+	if (status == "error")
+	{
+		qCritical() << "paste.ee reported error:" << QString(object.value("error").toString());
+		return false;
+	}
+	m_pasteLink = object.value("paste").toObject().value("link").toString();
+	m_pasteID = object.value("paste").toObject().value("id").toString();
+	return true;
+}
+
diff --git a/libraries/logic/net/PasteUpload.h b/libraries/logic/net/PasteUpload.h
new file mode 100644
index 00000000..06e3f955
--- /dev/null
+++ b/libraries/logic/net/PasteUpload.h
@@ -0,0 +1,50 @@
+#pragma once
+#include "tasks/Task.h"
+#include <QNetworkReply>
+#include <QBuffer>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT PasteUpload : public Task
+{
+	Q_OBJECT
+public:
+	PasteUpload(QWidget *window, QString text, QString key = "public");
+	virtual ~PasteUpload();
+	QString pasteLink()
+	{
+		return m_pasteLink;
+	}
+	QString pasteID()
+	{
+		return m_pasteID;
+	}
+	uint32_t maxSize()
+	{
+		// 2MB for paste.ee - public
+		if(m_key == "public")
+			return 1024*1024*2;
+		// 12MB for paste.ee - with actual key
+		return 1024*1024*12;
+	}
+	bool validateText();
+protected:
+	virtual void executeTask();
+
+private:
+	bool parseResult(QJsonDocument doc);
+	QByteArray m_text;
+	QString m_error;
+	QWidget *m_window;
+	QString m_pasteID;
+	QString m_pasteLink;
+	QString m_key;
+	int m_textSize = 0;
+	QBuffer * buf = nullptr;
+	std::shared_ptr<QNetworkReply> m_reply;
+public
+slots:
+	void downloadError(QNetworkReply::NetworkError);
+	void downloadFinished();
+};
diff --git a/libraries/logic/net/URLConstants.cpp b/libraries/logic/net/URLConstants.cpp
new file mode 100644
index 00000000..bd476b2c
--- /dev/null
+++ b/libraries/logic/net/URLConstants.cpp
@@ -0,0 +1,16 @@
+#include "URLConstants.h"
+
+namespace URLConstants {
+
+QString getLegacyJarUrl(QString version)
+{
+	return "http://" + AWS_DOWNLOAD_VERSIONS + getJarPath(version);
+}
+
+QString getJarPath(QString version)
+{
+	return version + "/" + version + ".jar";
+}
+
+
+}
diff --git a/libraries/logic/net/URLConstants.h b/libraries/logic/net/URLConstants.h
new file mode 100644
index 00000000..8923ef54
--- /dev/null
+++ b/libraries/logic/net/URLConstants.h
@@ -0,0 +1,40 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+
+namespace URLConstants
+{
+const QString AWS_DOWNLOAD_VERSIONS("s3.amazonaws.com/Minecraft.Download/versions/");
+const QString RESOURCE_BASE("resources.download.minecraft.net/");
+const QString LIBRARY_BASE("libraries.minecraft.net/");
+//const QString SKINS_BASE("skins.minecraft.net/MinecraftSkins/");
+const QString SKINS_BASE("crafatar.com/skins/");
+const QString AUTH_BASE("authserver.mojang.com/");
+const QString FORGE_LEGACY_URL("http://files.minecraftforge.net/minecraftforge/json");
+const QString FORGE_GRADLE_URL("http://files.minecraftforge.net/maven/net/minecraftforge/forge/json");
+const QString MOJANG_STATUS_URL("http://status.mojang.com/check");
+const QString MOJANG_STATUS_NEWS_URL("http://status.mojang.com/news");
+const QString LITELOADER_URL("http://dl.liteloader.com/versions/versions.json");
+const QString IMGUR_BASE_URL("https://api.imgur.com/3/");
+const QString FMLLIBS_OUR_BASE_URL("http://files.multimc.org/fmllibs/");
+const QString FMLLIBS_FORGE_BASE_URL("http://files.minecraftforge.net/fmllibs/");
+const QString TRANSLATIONS_BASE_URL("http://files.multimc.org/translations/");
+
+QString getJarPath(QString version);
+QString getLegacyJarUrl(QString version);
+}
diff --git a/libraries/logic/news/NewsChecker.cpp b/libraries/logic/news/NewsChecker.cpp
new file mode 100644
index 00000000..be4aa1d1
--- /dev/null
+++ b/libraries/logic/news/NewsChecker.cpp
@@ -0,0 +1,135 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "NewsChecker.h"
+
+#include <QByteArray>
+#include <QDomDocument>
+
+#include <QDebug>
+
+NewsChecker::NewsChecker(const QString& feedUrl)
+{
+	m_feedUrl = feedUrl;
+}
+
+void NewsChecker::reloadNews()
+{
+	// Start a netjob to download the RSS feed and call rssDownloadFinished() when it's done.
+	if (isLoadingNews())
+	{
+		qDebug() << "Ignored request to reload news. Currently reloading already.";
+		return;
+	}
+
+	qDebug() << "Reloading news.";
+
+	NetJob* job = new NetJob("News RSS Feed");
+	job->addNetAction(ByteArrayDownload::make(m_feedUrl));
+	QObject::connect(job, &NetJob::succeeded, this, &NewsChecker::rssDownloadFinished);
+	QObject::connect(job, &NetJob::failed, this, &NewsChecker::rssDownloadFailed);
+	m_newsNetJob.reset(job);
+	job->start();
+}
+
+void NewsChecker::rssDownloadFinished()
+{
+	// Parse the XML file and process the RSS feed entries.
+	qDebug() << "Finished loading RSS feed.";
+
+	QByteArray data;
+	{
+		ByteArrayDownloadPtr dl = std::dynamic_pointer_cast<ByteArrayDownload>(m_newsNetJob->first());
+		data = dl->m_data;
+		m_newsNetJob.reset();
+	}
+
+	QDomDocument doc;
+	{
+		// Stuff to store error info in.
+		QString errorMsg = "Unknown error.";
+		int errorLine = -1;
+		int errorCol = -1;
+
+		// Parse the XML.
+		if (!doc.setContent(data, false, &errorMsg, &errorLine, &errorCol))
+		{
+			QString fullErrorMsg = QString("Error parsing RSS feed XML. %s at %d:%d.").arg(errorMsg, errorLine, errorCol);
+			fail(fullErrorMsg);
+			return;
+		}
+	}
+
+	// If the parsing succeeded, read it.
+	QDomNodeList items = doc.elementsByTagName("item");
+	m_newsEntries.clear();
+	for (int i = 0; i < items.length(); i++)
+	{
+		QDomElement element = items.at(i).toElement();
+		NewsEntryPtr entry;
+		entry.reset(new NewsEntry());
+		QString errorMsg = "An unknown error occurred.";
+		if (NewsEntry::fromXmlElement(element, entry.get(), &errorMsg))
+		{
+			qDebug() << "Loaded news entry" << entry->title;
+			m_newsEntries.append(entry);
+		}
+		else
+		{
+			qWarning() << "Failed to load news entry at index" << i << ":" << errorMsg;
+		}
+	}
+
+	succeed();
+}
+
+void NewsChecker::rssDownloadFailed(QString reason)
+{
+	// Set an error message and fail.
+	fail(tr("Failed to load news RSS feed:\n%1").arg(reason));
+}
+
+
+QList<NewsEntryPtr> NewsChecker::getNewsEntries() const
+{
+	return m_newsEntries;
+}
+
+bool NewsChecker::isLoadingNews() const
+{
+	return m_newsNetJob.get() != nullptr;
+}
+
+QString NewsChecker::getLastLoadErrorMsg() const
+{
+	return m_lastLoadError;
+}
+
+void NewsChecker::succeed()
+{
+	m_lastLoadError = "";
+	qDebug() << "News loading succeeded.";
+	m_newsNetJob.reset();
+	emit newsLoaded();
+}
+
+void NewsChecker::fail(const QString& errorMsg)
+{
+	m_lastLoadError = errorMsg;
+	qDebug() << "Failed to load news:" << errorMsg;
+	m_newsNetJob.reset();
+	emit newsLoadingFailed(errorMsg);
+}
+
diff --git a/libraries/logic/news/NewsChecker.h b/libraries/logic/news/NewsChecker.h
new file mode 100644
index 00000000..b8b90728
--- /dev/null
+++ b/libraries/logic/news/NewsChecker.h
@@ -0,0 +1,107 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QString>
+#include <QList>
+
+#include <net/NetJob.h>
+
+#include "NewsEntry.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT NewsChecker : public QObject
+{
+	Q_OBJECT
+public:
+	/*!
+	 * Constructs a news reader to read from the given RSS feed URL.
+	 */
+	NewsChecker(const QString& feedUrl);
+
+	/*!
+	 * Returns the error message for the last time the news was loaded.
+	 * Empty string if the last load was successful.
+	 */
+	QString getLastLoadErrorMsg() const;
+
+	/*!
+	 * Returns true if the news has been loaded successfully.
+	 */
+	bool isNewsLoaded() const;
+
+	//! True if the news is currently loading. If true, reloadNews() will do nothing.
+	bool isLoadingNews() const;
+
+	/*!
+	 * Returns a list of news entries.
+	 */
+	QList<NewsEntryPtr> getNewsEntries() const;
+
+	/*!
+	 * Reloads the news from the website's RSS feed.
+	 * If the news is already loading, this does nothing.
+	 */
+	void Q_SLOT reloadNews();
+
+signals:
+	/*!
+	 * Signal fired after the news has finished loading.
+	 */
+	void newsLoaded();
+
+	/*!
+	 * Signal fired after the news fails to load.
+	 */
+	void newsLoadingFailed(QString errorMsg);
+
+protected slots:
+	void rssDownloadFinished();
+	void rssDownloadFailed(QString reason);
+
+protected:
+	//! The URL for the RSS feed to fetch.
+	QString m_feedUrl;
+
+	//! List of news entries.
+	QList<NewsEntryPtr> m_newsEntries;
+
+	//! The network job to use to load the news.
+	NetJobPtr m_newsNetJob;
+
+	//! True if news has been loaded.
+	bool m_loadedNews;
+
+	/*!
+	 * Gets the error message that was given last time the news was loaded.
+	 * If the last news load succeeded, this will be an empty string.
+	 */
+	QString m_lastLoadError;
+
+
+	/*!
+	 * Emits newsLoaded() and sets m_lastLoadError to empty string.
+	 */
+	void Q_SLOT succeed();
+
+	/*!
+	 * Emits newsLoadingFailed() and sets m_lastLoadError to the given message.
+	 */
+	void Q_SLOT fail(const QString& errorMsg);
+};
+
diff --git a/libraries/logic/news/NewsEntry.cpp b/libraries/logic/news/NewsEntry.cpp
new file mode 100644
index 00000000..79abbaa3
--- /dev/null
+++ b/libraries/logic/news/NewsEntry.cpp
@@ -0,0 +1,77 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "NewsEntry.h"
+
+#include <QDomNodeList>
+#include <QVariant>
+
+NewsEntry::NewsEntry(QObject* parent) :
+	QObject(parent)
+{
+	this->title = tr("Untitled");
+	this->content = tr("No content.");
+	this->link = "";
+	this->author = tr("Unknown Author");
+	this->pubDate = QDateTime::currentDateTime();
+}
+
+NewsEntry::NewsEntry(const QString& title, const QString& content, const QString& link, const QString& author, const QDateTime& pubDate, QObject* parent) :
+	QObject(parent)
+{
+	this->title = title;
+	this->content = content;
+	this->link = link;
+	this->author = author;
+	this->pubDate = pubDate;
+}
+
+/*!
+ * Gets the text content of the given child element as a QVariant.
+ */
+inline QString childValue(const QDomElement& element, const QString& childName, QString defaultVal="")
+{
+	QDomNodeList nodes = element.elementsByTagName(childName);
+	if (nodes.count() > 0)
+	{
+		QDomElement element = nodes.at(0).toElement();
+		return element.text();
+	}
+	else
+	{
+		return defaultVal;
+	}
+}
+
+bool NewsEntry::fromXmlElement(const QDomElement& element, NewsEntry* entry, QString* errorMsg)
+{
+	QString title = childValue(element, "title", tr("Untitled"));
+	QString content = childValue(element, "description", tr("No content."));
+	QString link = childValue(element, "link");
+	QString author = childValue(element, "dc:creator", tr("Unknown Author"));
+	QString pubDateStr = childValue(element, "pubDate");
+
+	// FIXME: For now, we're just ignoring timezones. We assume that all time zones in the RSS feed are the same.
+	QString dateFormat("ddd, dd MMM yyyy hh:mm:ss");
+	QDateTime pubDate = QDateTime::fromString(pubDateStr, dateFormat);
+
+	entry->title = title;
+	entry->content = content;
+	entry->link = link;
+	entry->author = author;
+	entry->pubDate = pubDate;
+	return true;
+}
+
diff --git a/libraries/logic/news/NewsEntry.h b/libraries/logic/news/NewsEntry.h
new file mode 100644
index 00000000..adb79e8f
--- /dev/null
+++ b/libraries/logic/news/NewsEntry.h
@@ -0,0 +1,65 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QString>
+#include <QDomElement>
+#include <QDateTime>
+
+#include <memory>
+
+class NewsEntry : public QObject
+{
+	Q_OBJECT
+
+public:
+	/*!
+	 * Constructs an empty news entry.
+	 */
+	explicit NewsEntry(QObject* parent=0);
+
+	/*!
+	 * Constructs a new news entry.
+	 * Note that content may contain HTML.
+	 */
+	NewsEntry(const QString& title, const QString& content, const QString& link, const QString& author, const QDateTime& pubDate, QObject* parent=0);
+
+	/*!
+	 * Attempts to load information from the given XML element into the given news entry pointer.
+	 * If this fails, the function will return false and store an error message in the errorMsg pointer.
+	 */
+	static bool fromXmlElement(const QDomElement& element, NewsEntry* entry, QString* errorMsg=0);
+
+
+	//! The post title.
+	QString title;
+
+	//! The post's content. May contain HTML.
+	QString content;
+
+	//! URL to the post.
+	QString link;
+
+	//! The post's author.
+	QString author;
+	
+	//! The date and time that this post was published.
+	QDateTime pubDate;
+};
+
+typedef std::shared_ptr<NewsEntry> NewsEntryPtr;
+
diff --git a/libraries/logic/notifications/NotificationChecker.cpp b/libraries/logic/notifications/NotificationChecker.cpp
new file mode 100644
index 00000000..ab2570b7
--- /dev/null
+++ b/libraries/logic/notifications/NotificationChecker.cpp
@@ -0,0 +1,130 @@
+#include "NotificationChecker.h"
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QDebug>
+
+#include "Env.h"
+#include "net/CacheDownload.h"
+
+
+NotificationChecker::NotificationChecker(QObject *parent)
+	: QObject(parent)
+{
+}
+
+void NotificationChecker::setNotificationsUrl(const QUrl &notificationsUrl)
+{
+	m_notificationsUrl = notificationsUrl;
+}
+
+void NotificationChecker::setApplicationChannel(QString channel)
+{
+	m_appVersionChannel = channel;
+}
+
+void NotificationChecker::setApplicationFullVersion(QString version)
+{
+	m_appFullVersion = version;
+}
+
+void NotificationChecker::setApplicationPlatform(QString platform)
+{
+	m_appPlatform = platform;
+}
+
+QList<NotificationChecker::NotificationEntry> NotificationChecker::notificationEntries() const
+{
+	return m_entries;
+}
+
+void NotificationChecker::checkForNotifications()
+{
+	if (!m_notificationsUrl.isValid())
+	{
+		qCritical() << "Failed to check for notifications. No notifications URL set."
+					 << "If you'd like to use MultiMC's notification system, please pass the "
+						"URL to CMake at compile time.";
+		return;
+	}
+	if (m_checkJob)
+	{
+		return;
+	}
+	m_checkJob.reset(new NetJob("Checking for notifications"));
+	auto entry = ENV.metacache()->resolveEntry("root", "notifications.json");
+	entry->setStale(true);
+	m_checkJob->addNetAction(m_download = CacheDownload::make(m_notificationsUrl, entry));
+	connect(m_download.get(), &CacheDownload::succeeded, this,
+			&NotificationChecker::downloadSucceeded);
+	m_checkJob->start();
+}
+
+void NotificationChecker::downloadSucceeded(int)
+{
+	m_entries.clear();
+
+	QFile file(m_download->getTargetFilepath());
+	if (file.open(QFile::ReadOnly))
+	{
+		QJsonArray root = QJsonDocument::fromJson(file.readAll()).array();
+		for (auto it = root.begin(); it != root.end(); ++it)
+		{
+			QJsonObject obj = (*it).toObject();
+			NotificationEntry entry;
+			entry.id = obj.value("id").toDouble();
+			entry.message = obj.value("message").toString();
+			entry.channel = obj.value("channel").toString();
+			entry.platform = obj.value("platform").toString();
+			entry.from = obj.value("from").toString();
+			entry.to = obj.value("to").toString();
+			const QString type = obj.value("type").toString("critical");
+			if (type == "critical")
+			{
+				entry.type = NotificationEntry::Critical;
+			}
+			else if (type == "warning")
+			{
+				entry.type = NotificationEntry::Warning;
+			}
+			else if (type == "information")
+			{
+				entry.type = NotificationEntry::Information;
+			}
+			if(entryApplies(entry))
+				m_entries.append(entry);
+		}
+	}
+
+	m_checkJob.reset();
+
+	emit notificationCheckFinished();
+}
+
+bool versionLessThan(const QString &v1, const QString &v2)
+{
+	QStringList l1 = v1.split('.');
+	QStringList l2 = v2.split('.');
+	while (!l1.isEmpty() && !l2.isEmpty())
+	{
+		int one = l1.isEmpty() ? 0 : l1.takeFirst().toInt();
+		int two = l2.isEmpty() ? 0 : l2.takeFirst().toInt();
+		if (one != two)
+		{
+			return one < two;
+		}
+	}
+	return false;
+}
+
+bool NotificationChecker::entryApplies(const NotificationChecker::NotificationEntry& entry) const
+{
+	bool channelApplies = entry.channel.isEmpty() || entry.channel == m_appVersionChannel;
+	bool platformApplies = entry.platform.isEmpty() || entry.platform == m_appPlatform;
+	bool fromApplies =
+		entry.from.isEmpty() || entry.from == m_appFullVersion || !versionLessThan(m_appFullVersion, entry.from);
+	bool toApplies =
+		entry.to.isEmpty() || entry.to == m_appFullVersion || !versionLessThan(entry.to, m_appFullVersion);
+	return channelApplies && platformApplies && fromApplies && toApplies;
+}
diff --git a/libraries/logic/notifications/NotificationChecker.h b/libraries/logic/notifications/NotificationChecker.h
new file mode 100644
index 00000000..a2d92ab9
--- /dev/null
+++ b/libraries/logic/notifications/NotificationChecker.h
@@ -0,0 +1,63 @@
+#pragma once
+
+#include <QObject>
+
+#include "net/NetJob.h"
+#include "net/CacheDownload.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT NotificationChecker : public QObject
+{
+	Q_OBJECT
+
+public:
+	explicit NotificationChecker(QObject *parent = 0);
+
+	void setNotificationsUrl(const QUrl &notificationsUrl);
+	void setApplicationPlatform(QString platform);
+	void setApplicationChannel(QString channel);
+	void setApplicationFullVersion(QString version);
+
+	struct NotificationEntry
+	{
+		int id;
+		QString message;
+		enum
+		{
+			Critical,
+			Warning,
+			Information
+		} type;
+		QString channel;
+		QString platform;
+		QString from;
+		QString to;
+	};
+
+	QList<NotificationEntry> notificationEntries() const;
+
+public
+slots:
+	void checkForNotifications();
+
+private
+slots:
+	void downloadSucceeded(int);
+
+signals:
+	void notificationCheckFinished();
+
+private:
+	bool entryApplies(const NotificationEntry &entry) const;
+
+private:
+	QList<NotificationEntry> m_entries;
+	QUrl m_notificationsUrl;
+	NetJobPtr m_checkJob;
+	CacheDownloadPtr m_download;
+
+	QString m_appVersionChannel;
+	QString m_appPlatform;
+	QString m_appFullVersion;
+};
diff --git a/libraries/logic/pathmatcher/FSTreeMatcher.h b/libraries/logic/pathmatcher/FSTreeMatcher.h
new file mode 100644
index 00000000..a5bed57c
--- /dev/null
+++ b/libraries/logic/pathmatcher/FSTreeMatcher.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "IPathMatcher.h"
+#include <SeparatorPrefixTree.h>
+#include <QRegularExpression>
+
+class FSTreeMatcher : public IPathMatcher
+{
+public:
+	virtual ~FSTreeMatcher() {};
+	FSTreeMatcher(SeparatorPrefixTree<'/'> & tree) : m_fsTree(tree)
+	{
+	}
+
+	virtual bool matches(const QString &string) const override
+	{
+		return m_fsTree.covers(string);
+	}
+
+	SeparatorPrefixTree<'/'> & m_fsTree;
+};
diff --git a/libraries/logic/pathmatcher/IPathMatcher.h b/libraries/logic/pathmatcher/IPathMatcher.h
new file mode 100644
index 00000000..1d410947
--- /dev/null
+++ b/libraries/logic/pathmatcher/IPathMatcher.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <memory>
+
+class IPathMatcher
+{
+public:
+	typedef std::shared_ptr<IPathMatcher> Ptr;
+
+public:
+	virtual ~IPathMatcher(){};
+	virtual bool matches(const QString &string) const = 0;
+};
diff --git a/libraries/logic/pathmatcher/MultiMatcher.h b/libraries/logic/pathmatcher/MultiMatcher.h
new file mode 100644
index 00000000..91f70aa4
--- /dev/null
+++ b/libraries/logic/pathmatcher/MultiMatcher.h
@@ -0,0 +1,31 @@
+#include "IPathMatcher.h"
+#include <SeparatorPrefixTree.h>
+#include <QRegularExpression>
+
+class MultiMatcher : public IPathMatcher
+{
+public:
+	virtual ~MultiMatcher() {};
+	MultiMatcher()
+	{
+	}
+	MultiMatcher &add(Ptr add)
+	{
+		m_matchers.append(add);
+		return *this;
+	}
+
+	virtual bool matches(const QString &string) const override
+	{
+		for(auto iter: m_matchers)
+		{
+			if(iter->matches(string))
+			{
+				return true;
+			}
+		}
+		return false;
+	}
+
+	QList<Ptr> m_matchers;
+};
diff --git a/libraries/logic/pathmatcher/RegexpMatcher.h b/libraries/logic/pathmatcher/RegexpMatcher.h
new file mode 100644
index 00000000..da552123
--- /dev/null
+++ b/libraries/logic/pathmatcher/RegexpMatcher.h
@@ -0,0 +1,42 @@
+#include "IPathMatcher.h"
+#include <QRegularExpression>
+
+class RegexpMatcher : public IPathMatcher
+{
+public:
+	virtual ~RegexpMatcher() {};
+	RegexpMatcher(const QString &regexp)
+	{
+		m_regexp.setPattern(regexp);
+		m_onlyFilenamePart = !regexp.contains('/');
+	}
+
+	RegexpMatcher &caseSensitive(bool cs = true)
+	{
+		if(cs)
+		{
+			m_regexp.setPatternOptions(QRegularExpression::CaseInsensitiveOption);
+		}
+		else
+		{
+			m_regexp.setPatternOptions(QRegularExpression::NoPatternOption);
+		}
+		return *this;
+	}
+
+	virtual bool matches(const QString &string) const override
+	{
+		if(m_onlyFilenamePart)
+		{
+			auto slash = string.lastIndexOf('/');
+			if(slash != -1)
+			{
+				auto part = string.mid(slash + 1);
+				return m_regexp.match(part).hasMatch();
+			}
+		}
+		return m_regexp.match(string).hasMatch();
+	}
+	QRegularExpression m_regexp;
+	bool m_onlyFilenamePart = false;
+};
diff --git a/libraries/logic/resources/Resource.cpp b/libraries/logic/resources/Resource.cpp
new file mode 100644
index 00000000..e95675d7
--- /dev/null
+++ b/libraries/logic/resources/Resource.cpp
@@ -0,0 +1,155 @@
+#include "Resource.h"
+
+#include <QDebug>
+
+#include "ResourceObserver.h"
+#include "ResourceHandler.h"
+
+// definition of static members of Resource
+QMap<QString, std::function<std::shared_ptr<ResourceHandler>(const QString &)>> Resource::m_handlers;
+QMap<QPair<int, int>, std::function<QVariant(QVariant)>> Resource::m_transfomers;
+QMap<QString, std::weak_ptr<Resource>> Resource::m_resources;
+
+struct NullResourceResult {};
+Q_DECLARE_METATYPE(NullResourceResult)
+class NullResourceHandler : public ResourceHandler
+{
+public:
+	explicit NullResourceHandler()
+	{
+		setResult(QVariant::fromValue<NullResourceResult>(NullResourceResult()));
+	}
+};
+
+Resource::Resource(const QString &resource)
+	: m_resource(resource)
+{
+	if (!resource.isEmpty())
+	{
+		// a valid resource identifier has the format <id>:<data>
+		Q_ASSERT(resource.contains(':'));
+		// "parse" the resource identifier into id and data
+		const QString resourceId = resource.left(resource.indexOf(':'));
+		const QString resourceData = resource.mid(resource.indexOf(':') + 1);
+
+		// create and set up the handler
+		Q_ASSERT(m_handlers.contains(resourceId));
+		m_handler = m_handlers.value(resourceId)(resourceData);
+	}
+	else
+	{
+		m_handler = std::make_shared<NullResourceHandler>();
+	}
+
+	Q_ASSERT(m_handler);
+	m_handler->init(m_handler);
+	m_handler->setResource(this);
+}
+Resource::~Resource()
+{
+	qDeleteAll(m_observers);
+}
+
+Resource::Ptr Resource::create(const QString &resource, Ptr placeholder)
+{
+	const QString storageId = storageIdentifier(resource, placeholder);
+
+	// do we already have a resource? even if m_resources contains it it might not be valid any longer (weak_ptr)
+	Resource::Ptr ptr = m_resources.contains(storageId)
+			? m_resources.value(storageId).lock()
+			: nullptr;
+	// did we have one? and is it still valid?
+	if (!ptr)
+	{
+		/* We don't want Resource to have a public constructor, but std::make_shared needs it,
+		 * so we create a subclass of Resource here that exposes the constructor as public.
+		 * The alternative would be making the allocator for std::make_shared a friend, but it
+		 * differs between different STL implementations, so that would be a pain.
+		 */
+		struct ConstructableResource : public Resource
+		{
+			explicit ConstructableResource(const QString &resource)
+				: Resource(resource) {}
+		};
+		ptr = std::make_shared<ConstructableResource>(resource);
+		ptr->m_placeholder = placeholder;
+		m_resources.insert(storageId, ptr);
+	}
+	return ptr;
+}
+
+Resource::Ptr Resource::applyTo(ResourceObserver *observer)
+{
+	m_observers.append(observer);
+	observer->setSource(shared_from_this()); // give the observer a shared_ptr for us so we don't get deleted
+	observer->resourceUpdated(); // ask the observer to poll us immediently, we might already have data
+	return shared_from_this(); // allow chaining
+}
+Resource::Ptr Resource::applyTo(QObject *target, const char *property)
+{
+	// the cast to ResourceObserver* is required to ensure the right overload gets choosen,
+	// since QObjectResourceObserver also inherits from QObject
+	return applyTo(static_cast<ResourceObserver *>(new QObjectResourceObserver(target, property)));
+}
+
+QVariant Resource::getResourceInternal(const int typeId) const
+{
+	// no result (yet), but a placeholder? delegate to the placeholder.
+	if (m_handler->result().isNull() && m_placeholder)
+	{
+		return m_placeholder->getResourceInternal(typeId);
+	}
+	const QVariant variant = m_handler->result();
+	const auto typePair = qMakePair(int(variant.type()), typeId);
+
+	// do we have an explicit transformer? use it.
+	if (m_transfomers.contains(typePair))
+	{
+		return m_transfomers.value(typePair)(variant);
+	}
+	else
+	{
+		// we do not have an explicit transformer, so we just pass the QVariant, which will automatically
+		// transform some types for us (different numbers to each other etc.)
+		return variant;
+	}
+}
+
+void Resource::reportResult()
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->resourceUpdated();
+	}
+}
+void Resource::reportFailure(const QString &reason)
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->setFailure(reason);
+	}
+}
+void Resource::reportProgress(const int progress)
+{
+	for (ResourceObserver *observer : m_observers)
+	{
+		observer->setProgress(progress);
+	}
+}
+
+void Resource::notifyObserverDeleted(ResourceObserver *observer)
+{
+	m_observers.removeAll(observer);
+}
+
+QString Resource::storageIdentifier(const QString &id, Resource::Ptr placeholder)
+{
+	if (placeholder)
+	{
+		return id + '#' + storageIdentifier(placeholder->m_resource, placeholder->m_placeholder);
+	}
+	else
+	{
+		return id;
+	}
+}
diff --git a/libraries/logic/resources/Resource.h b/libraries/logic/resources/Resource.h
new file mode 100644
index 00000000..63e97b88
--- /dev/null
+++ b/libraries/logic/resources/Resource.h
@@ -0,0 +1,132 @@
+#pragma once
+
+#include <QString>
+#include <QMap>
+#include <QVariant>
+#include <functional>
+#include <memory>
+
+#include "ResourceObserver.h"
+#include "TypeMagic.h"
+
+#include "multimc_logic_export.h"
+
+class ResourceHandler;
+
+/** Frontend class for resources
+ *
+ * Usage:
+ *	Resource::create("icon:noaccount")->applyTo(accountsAction);
+ *	Resource::create("web:http://asdf.com/image.png")->applyTo(imageLbl)->placeholder(Resource::create("icon:loading"));
+ *
+ * Memory management:
+ *	Resource caches ResourcePtrs using weak pointers, so while a resource is still existing
+ *	when a new resource is created the resources will be the same (including the same handler).
+ *
+ *	ResourceObservers keep a shared pointer to the resource, as does the Resource itself to it's
+ *	placeholder (if present). This means a resource stays valid while it's still used ("applied to" etc.)
+ *	by something. When nothing uses it anymore it gets deleted.
+ *
+ *	@note Always pass resource around using Resource::Ptr! Copy and move constructors are disabled for a reason.
+ */
+class MULTIMC_LOGIC_EXPORT Resource : public std::enable_shared_from_this<Resource>
+{
+	// only allow creation from Resource::create and disallow passing around non-pointers
+	explicit Resource(const QString &resource);
+	Resource(const Resource &) = delete;
+	Resource(Resource &&) = delete;
+public:
+	using Ptr = std::shared_ptr<Resource>;
+
+	~Resource();
+
+	/// The returned pointer needs to be stored until either Resource::applyTo or Resource::then is called, or it is passed as
+	/// a placeholder to Resource::create itself.
+	static Ptr create(const QString &resource, Ptr placeholder = nullptr);
+
+	/// Use these functions to specify what should happen when e.g. the resource changes
+	Ptr applyTo(ResourceObserver *observer);
+	Ptr applyTo(QObject *target, const char *property = nullptr);
+	template<typename Func>
+	Ptr then(Func &&func)
+	{
+		// Arg will be the functions argument with references and cv-qualifiers (const, volatile) removed
+		using Arg = TypeMagic::CleanType<typename TypeMagic::Function<Func>::Argument>;
+		// Ret will be the functions return type
+		using Ret = typename TypeMagic::Function<Func>::ReturnType;
+
+		// FunctionResourceObserver<ReturnType, ArgumentType, FunctionSignature>
+		return applyTo(new FunctionResourceObserver<Ret, Arg, Func>(std::forward<Func>(func)));
+	}
+
+	/// Retrieve the currently active resource. If it's type is different from T a conversion will be attempted.
+	template<typename T>
+	T getResource() const { return getResourceInternal(qMetaTypeId<T>()).template value<T>(); }
+
+	/// @internal Used by ResourceObserver and ResourceProxyModel
+	QVariant getResourceInternal(const int typeId) const;
+
+	/** Register a new ResourceHandler. T needs to inherit from ResourceHandler
+	 * Usage: Resource::registerHandler<MyResourceHandler>("myid");
+	 */
+	template<typename T>
+	static void registerHandler(const QString &id)
+	{
+		m_handlers.insert(id, [](const QString &res) { return std::make_shared<T>(res); });
+	}
+	/** Register a new resource transformer
+	 * Resource transformers are functions that are responsible for converting between different types,
+	 * for example converting from a QByteArray to a QPixmap. They are registered "externally" because not
+	 * all types might be available in this library, for example gui types like QPixmap.
+	 *
+	 * Usage: Resource::registerTransformer([](const InputType &type) { return OutputType(type); });
+	 *   This assumes that OutputType has a constructor that takes InputType as an argument. More
+	 *   complicated transformers can of course also be registered.
+	 *
+	 * When a ResourceObserver requests a type that's different from the actual resource type, a matching
+	 * transformer will be looked up from the list of transformers.
+	 * @note Only one-stage transforms will be performed (you can't registerTransformers for QString => int
+	 *       and int => float and expect QString to automatically be transformed into a float.
+	 */
+	template<typename Func>
+	static void registerTransformer(Func &&func)
+	{
+		using Out = typename TypeMagic::Function<Func>::ReturnType;
+		using In = TypeMagic::CleanType<typename TypeMagic::Function<Func>::Argument>;
+		static_assert(!std::is_same<Out, In>::value, "It does not make sense to transform a value to itself");
+		m_transfomers.insert(qMakePair(qMetaTypeId<In>(), qMetaTypeId<Out>()), [func](const QVariant &in)
+		{
+			return QVariant::fromValue<Out>(func(in.value<In>()));
+		});
+	}
+
+private: // half private, implementation details
+	friend class ResourceHandler;
+	// the following three functions are called by ResourceHandlers
+	/** Notifies the observers. They will call Resource::getResourceInternal which will call ResourceHandler::result
+	 * or delegate to it's placeholder.
+	 */
+	void reportResult();
+	void reportFailure(const QString &reason);
+	void reportProgress(const int progress);
+
+	friend class ResourceObserver;
+	/// Removes observer from the list of observers so that we don't attempt to notify something that doesn't exist
+	void notifyObserverDeleted(ResourceObserver *observer);
+
+private: // truly private
+	QList<ResourceObserver *> m_observers;
+	std::shared_ptr<ResourceHandler> m_handler = nullptr;
+	Ptr m_placeholder = nullptr;
+	const QString m_resource;
+
+	static QString storageIdentifier(const QString &id, Ptr placeholder = nullptr);
+	QString storageIdentifier() const;
+
+	// a list of resource handler factories, registered using registerHandler
+	static QMap<QString, std::function<std::shared_ptr<ResourceHandler>(const QString &)>> m_handlers;
+	// a list of resource transformers, registered using registerTransformer
+	static QMap<QPair<int, int>, std::function<QVariant(QVariant)>> m_transfomers;
+	// a list of resources so that we can reuse them
+	static QMap<QString, std::weak_ptr<Resource>> m_resources;
+};
diff --git a/libraries/logic/resources/ResourceHandler.cpp b/libraries/logic/resources/ResourceHandler.cpp
new file mode 100644
index 00000000..46a4422c
--- /dev/null
+++ b/libraries/logic/resources/ResourceHandler.cpp
@@ -0,0 +1,28 @@
+#include "ResourceHandler.h"
+
+#include "Resource.h"
+
+void ResourceHandler::setResult(const QVariant &result)
+{
+	m_result = result;
+	if (m_resource)
+	{
+		m_resource->reportResult();
+	}
+}
+
+void ResourceHandler::setFailure(const QString &reason)
+{
+	if (m_resource)
+	{
+		m_resource->reportFailure(reason);
+	}
+}
+
+void ResourceHandler::setProgress(const int progress)
+{
+	if (m_resource)
+	{
+		m_resource->reportProgress(progress);
+	}
+}
diff --git a/libraries/logic/resources/ResourceHandler.h b/libraries/logic/resources/ResourceHandler.h
new file mode 100644
index 00000000..f09d8904
--- /dev/null
+++ b/libraries/logic/resources/ResourceHandler.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include <QVariant>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class Resource;
+
+/** Base class for things that can retrieve a resource.
+ *
+ * Subclass, provide a constructor that takes a single QString as argument, and
+ * call Resource::registerHandler<MyResourceHandler>("<id>"), where <id> is the
+ * prefix of the resource ("web", "icon", etc.)
+ */
+class MULTIMC_LOGIC_EXPORT ResourceHandler
+{
+public:
+	virtual ~ResourceHandler() {}
+
+	void setResource(Resource *resource) { m_resource = resource; }
+	/// reimplement this if you need to do something after you have been put in a shared pointer
+	// we do this instead of inheriting from std::enable_shared_from_this
+	virtual void init(std::shared_ptr<ResourceHandler>&) {}
+
+	QVariant result() const { return m_result; }
+
+protected: // use these methods to notify the resource of changes
+	void setResult(const QVariant &result);
+	void setFailure(const QString &reason);
+	void setProgress(const int progress);
+
+private:
+	QVariant m_result;
+	Resource *m_resource = nullptr;
+};
diff --git a/libraries/logic/resources/ResourceObserver.cpp b/libraries/logic/resources/ResourceObserver.cpp
new file mode 100644
index 00000000..4f168fd2
--- /dev/null
+++ b/libraries/logic/resources/ResourceObserver.cpp
@@ -0,0 +1,55 @@
+#include "ResourceObserver.h"
+
+#include <QDebug>
+
+#include "Resource.h"
+
+static const char *defaultPropertyForTarget(QObject *target)
+{
+	if (target->inherits("QLabel"))
+	{
+		return "pixmap";
+	}
+	else if (target->inherits("QAction") ||
+			 target->inherits("QMenu") ||
+			 target->inherits("QAbstractButton"))
+	{
+		return "icon";
+	}
+	// for unit tests
+	else if (target->inherits("DummyObserverObject"))
+	{
+		return "property";
+	}
+	else
+	{
+		Q_ASSERT_X(false, "ResourceObserver.cpp: defaultPropertyForTarget", "Unrecognized QObject subclass");
+		return nullptr;
+	}
+}
+
+QObjectResourceObserver::QObjectResourceObserver(QObject *target, const char *property)
+	: QObject(target), m_target(target)
+{
+	const QMetaObject *mo = m_target->metaObject();
+	m_property = mo->property(mo->indexOfProperty(
+								  property ?
+									  property
+									: defaultPropertyForTarget(target)));
+}
+void QObjectResourceObserver::resourceUpdated()
+{
+	m_property.write(m_target, getInternal(m_property.type()));
+}
+
+
+ResourceObserver::~ResourceObserver()
+{
+	m_resource->notifyObserverDeleted(this);
+}
+
+QVariant ResourceObserver::getInternal(const int typeId) const
+{
+	Q_ASSERT(m_resource);
+	return m_resource->getResourceInternal(typeId);
+}
diff --git a/libraries/logic/resources/ResourceObserver.h b/libraries/logic/resources/ResourceObserver.h
new file mode 100644
index 00000000..c42e41ba
--- /dev/null
+++ b/libraries/logic/resources/ResourceObserver.h
@@ -0,0 +1,73 @@
+#pragma once
+
+#include <memory>
+#include <functional>
+
+#include <QObject>
+#include <QMetaProperty>
+#include "multimc_logic_export.h"
+
+class QVariant;
+class Resource;
+
+/// Base class for things that can use a resource
+class MULTIMC_LOGIC_EXPORT ResourceObserver
+{
+public:
+	virtual ~ResourceObserver();
+
+protected: // these methods are called by the Resource when something changes
+	virtual void resourceUpdated() = 0;
+	virtual void setFailure(const QString &) {}
+	virtual void setProgress(const int) {}
+
+private:
+	friend class Resource;
+	void setSource(std::shared_ptr<Resource> resource) { m_resource = resource; }
+
+protected:
+	template<typename T>
+	T get() const { return getInternal(qMetaTypeId<T>()).template value<T>(); }
+	QVariant getInternal(const int typeId) const;
+
+private:
+	std::shared_ptr<Resource> m_resource;
+};
+
+/** Observer for QObject properties
+ *
+ * Give it a target and the name of a property, and that property will be set when the resource changes.
+ *
+ * If no name is given an attempt to find a default property for some common classes is done.
+ */
+class MULTIMC_LOGIC_EXPORT QObjectResourceObserver : public QObject, public ResourceObserver
+{
+public:
+	explicit QObjectResourceObserver(QObject *target, const char *property = nullptr);
+
+	void resourceUpdated() override;
+
+private:
+	QObject *m_target;
+	QMetaProperty m_property;
+};
+
+/** Observer for functions, lambdas etc.
+ * Template arguments:
+ *   * We need Ret and Arg in order to create the std::function
+ *   * We need Func in order to std::forward the function
+ */
+template <typename Ret, typename Arg, typename Func>
+class FunctionResourceObserver : public ResourceObserver
+{
+	std::function<Ret(Arg)> m_function;
+public:
+	template <typename T>
+	explicit FunctionResourceObserver(T &&func)
+		: m_function(std::forward<Func>(func)) {}
+
+	void resourceUpdated() override
+	{
+		m_function(get<Arg>());
+	}
+};
diff --git a/libraries/logic/resources/ResourceProxyModel.cpp b/libraries/logic/resources/ResourceProxyModel.cpp
new file mode 100644
index 00000000..f026d9a9
--- /dev/null
+++ b/libraries/logic/resources/ResourceProxyModel.cpp
@@ -0,0 +1,89 @@
+#include "ResourceProxyModel.h"
+
+#include <QItemSelectionRange>
+
+#include "Resource.h"
+#include "ResourceObserver.h"
+
+class ModelResourceObserver : public ResourceObserver
+{
+public:
+	explicit ModelResourceObserver(const QModelIndex &index, const int role)
+		: m_index(index), m_role(role)
+	{
+		qRegisterMetaType<QVector<int>>("QVector<int>");
+	}
+
+	void resourceUpdated() override
+	{
+		if (m_index.isValid())
+		{
+			// the resource changed, pretend to be the model and notify the views of the update. they will re-poll the model which will return the new resource value
+			QMetaObject::invokeMethod(const_cast<QAbstractItemModel *>(m_index.model()),
+									  "dataChanged", Qt::QueuedConnection,
+									  Q_ARG(QModelIndex, m_index), Q_ARG(QModelIndex, m_index), Q_ARG(QVector<int>, QVector<int>() << m_role));
+		}
+	}
+
+private:
+	QPersistentModelIndex m_index;
+	int m_role;
+};
+
+ResourceProxyModel::ResourceProxyModel(const int resultTypeId, QObject *parent)
+	: QIdentityProxyModel(parent), m_resultTypeId(resultTypeId)
+{
+}
+
+QVariant ResourceProxyModel::data(const QModelIndex &proxyIndex, int role) const
+{
+	const QModelIndex mapped = mapToSource(proxyIndex);
+	// valid cell that's a Qt::DecorationRole and that contains a non-empty string
+	if (mapped.isValid() && role == Qt::DecorationRole && !mapToSource(proxyIndex).data(role).toString().isEmpty())
+	{
+		// do we already have a resource for this index?
+		if (!m_resources.contains(mapped))
+		{
+			Resource::Ptr placeholder;
+			const QVariant placeholderIdentifier = mapped.data(PlaceholderRole);
+			if (!placeholderIdentifier.isNull() && placeholderIdentifier.type() == QVariant::String)
+			{
+				placeholder = Resource::create(placeholderIdentifier.toString());
+			}
+
+			// create the Resource and apply the observer for models
+			Resource::Ptr res = Resource::create(mapToSource(proxyIndex).data(role).toString(), placeholder)
+					->applyTo(new ModelResourceObserver(proxyIndex, role));
+
+			m_resources.insert(mapped, res);
+		}
+
+		return m_resources.value(mapped)->getResourceInternal(m_resultTypeId);
+	}
+	// otherwise fall back to the source model
+	return mapped.data(role);
+}
+
+void ResourceProxyModel::setSourceModel(QAbstractItemModel *model)
+{
+	if (sourceModel())
+	{
+		disconnect(sourceModel(), 0, this, 0);
+	}
+	if (model)
+	{
+		connect(model, &QAbstractItemModel::dataChanged, this, [this](const QModelIndex &tl, const QModelIndex &br, const QVector<int> &roles)
+		{
+			// invalidate resources so that they will be re-created
+			if (roles.contains(Qt::DecorationRole) || roles.contains(PlaceholderRole) || roles.isEmpty())
+			{
+				const QItemSelectionRange range(tl, br);
+				for (const QModelIndex &index : range.indexes())
+				{
+					m_resources.remove(index);
+				}
+			}
+		});
+	}
+	QIdentityProxyModel::setSourceModel(model);
+}
diff --git a/libraries/logic/resources/ResourceProxyModel.h b/libraries/logic/resources/ResourceProxyModel.h
new file mode 100644
index 00000000..98a3dbd1
--- /dev/null
+++ b/libraries/logic/resources/ResourceProxyModel.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <QIdentityProxyModel>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+/// Convenience proxy model that transforms resource identifiers (strings) for Qt::DecorationRole into other types.
+class MULTIMC_LOGIC_EXPORT ResourceProxyModel : public QIdentityProxyModel
+{
+	Q_OBJECT
+public:
+	// resultTypeId is found using qMetaTypeId<T>()
+	explicit ResourceProxyModel(const int resultTypeId, QObject *parent = nullptr);
+
+	enum
+	{
+		// provide this role from your model if you want to show a placeholder
+		PlaceholderRole = Qt::UserRole + 0xabc // some random offset to not collide with other stuff
+	};
+
+	QVariant data(const QModelIndex &proxyIndex, int role) const override;
+	void setSourceModel(QAbstractItemModel *model) override;
+
+	/// Helper function, usage: m_view->setModel(ResourceProxyModel::mixin<QIcon>(m_model));
+	template <typename T>
+	static QAbstractItemModel *mixin(QAbstractItemModel *model)
+	{
+		ResourceProxyModel *proxy = new ResourceProxyModel(qMetaTypeId<T>(), model);
+		proxy->setSourceModel(model);
+		return proxy;
+	}
+
+private:
+	// mutable because it needs to be available from the const data()
+	mutable QMap<QPersistentModelIndex, std::shared_ptr<class Resource>> m_resources;
+
+	const int m_resultTypeId;
+};
diff --git a/libraries/logic/screenshots/ImgurAlbumCreation.cpp b/libraries/logic/screenshots/ImgurAlbumCreation.cpp
new file mode 100644
index 00000000..e009ef4d
--- /dev/null
+++ b/libraries/logic/screenshots/ImgurAlbumCreation.cpp
@@ -0,0 +1,90 @@
+#include "ImgurAlbumCreation.h"
+
+#include <QNetworkRequest>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QUrl>
+#include <QStringList>
+
+#include "net/URLConstants.h"
+#include "Env.h"
+#include <QDebug>
+
+ImgurAlbumCreation::ImgurAlbumCreation(QList<ScreenshotPtr> screenshots) : NetAction(), m_screenshots(screenshots)
+{
+	m_url = URLConstants::IMGUR_BASE_URL + "album.json";
+	m_status = Job_NotStarted;
+}
+
+void ImgurAlbumCreation::start()
+{
+	m_status = Job_InProgress;
+	QNetworkRequest request(m_url);
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Uncached)");
+	request.setHeader(QNetworkRequest::ContentTypeHeader, "application/x-www-form-urlencoded");
+	request.setRawHeader("Authorization", "Client-ID 5b97b0713fba4a3");
+	request.setRawHeader("Accept", "application/json");
+
+	QStringList ids;
+	for (auto shot : m_screenshots)
+	{
+		ids.append(shot->m_imgurId);
+	}
+
+	const QByteArray data = "ids=" + ids.join(',').toUtf8() + "&title=Minecraft%20Screenshots&privacy=hidden";
+
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->post(request, data);
+
+	m_reply.reset(rep);
+	connect(rep, &QNetworkReply::uploadProgress, this, &ImgurAlbumCreation::downloadProgress);
+	connect(rep, &QNetworkReply::finished, this, &ImgurAlbumCreation::downloadFinished);
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
+			SLOT(downloadError(QNetworkReply::NetworkError)));
+}
+void ImgurAlbumCreation::downloadError(QNetworkReply::NetworkError error)
+{
+	qDebug() << m_reply->errorString();
+	m_status = Job_Failed;
+}
+void ImgurAlbumCreation::downloadFinished()
+{
+	if (m_status != Job_Failed)
+	{
+		QByteArray data = m_reply->readAll();
+		m_reply.reset();
+		QJsonParseError jsonError;
+		QJsonDocument doc = QJsonDocument::fromJson(data, &jsonError);
+		if (jsonError.error != QJsonParseError::NoError)
+		{
+			qDebug() << jsonError.errorString();
+			emit failed(m_index_within_job);
+			return;
+		}
+		auto object = doc.object();
+		if (!object.value("success").toBool())
+		{
+			qDebug() << doc.toJson();
+			emit failed(m_index_within_job);
+			return;
+		}
+		m_deleteHash = object.value("data").toObject().value("deletehash").toString();
+		m_id = object.value("data").toObject().value("id").toString();
+		m_status = Job_Finished;
+		emit succeeded(m_index_within_job);
+		return;
+	}
+	else
+	{
+		qDebug() << m_reply->readAll();
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		return;
+	}
+}
+void ImgurAlbumCreation::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
+{
+	m_total_progress = bytesTotal;
+	m_progress = bytesReceived;
+	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
+}
diff --git a/libraries/logic/screenshots/ImgurAlbumCreation.h b/libraries/logic/screenshots/ImgurAlbumCreation.h
new file mode 100644
index 00000000..469174e4
--- /dev/null
+++ b/libraries/logic/screenshots/ImgurAlbumCreation.h
@@ -0,0 +1,44 @@
+#pragma once
+#include "net/NetAction.h"
+#include "Screenshot.h"
+
+#include "multimc_logic_export.h"
+
+typedef std::shared_ptr<class ImgurAlbumCreation> ImgurAlbumCreationPtr;
+class MULTIMC_LOGIC_EXPORT ImgurAlbumCreation : public NetAction
+{
+public:
+	explicit ImgurAlbumCreation(QList<ScreenshotPtr> screenshots);
+	static ImgurAlbumCreationPtr make(QList<ScreenshotPtr> screenshots)
+	{
+		return ImgurAlbumCreationPtr(new ImgurAlbumCreation(screenshots));
+	}
+
+	QString deleteHash() const
+	{
+		return m_deleteHash;
+	}
+	QString id() const
+	{
+		return m_id;
+	}
+
+protected
+slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	virtual void downloadError(QNetworkReply::NetworkError error);
+	virtual void downloadFinished();
+	virtual void downloadReadyRead()
+	{
+	}
+
+public
+slots:
+	virtual void start();
+
+private:
+	QList<ScreenshotPtr> m_screenshots;
+
+	QString m_deleteHash;
+	QString m_id;
+};
diff --git a/libraries/logic/screenshots/ImgurUpload.cpp b/libraries/logic/screenshots/ImgurUpload.cpp
new file mode 100644
index 00000000..48e0ec18
--- /dev/null
+++ b/libraries/logic/screenshots/ImgurUpload.cpp
@@ -0,0 +1,114 @@
+#include "ImgurUpload.h"
+
+#include <QNetworkRequest>
+#include <QHttpMultiPart>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QHttpPart>
+#include <QFile>
+#include <QUrl>
+
+#include "net/URLConstants.h"
+#include "Env.h"
+#include <QDebug>
+
+ImgurUpload::ImgurUpload(ScreenshotPtr shot) : NetAction(), m_shot(shot)
+{
+	m_url = URLConstants::IMGUR_BASE_URL + "upload.json";
+	m_status = Job_NotStarted;
+}
+
+void ImgurUpload::start()
+{
+	finished = false;
+	m_status = Job_InProgress;
+	QNetworkRequest request(m_url);
+	request.setHeader(QNetworkRequest::UserAgentHeader, "MultiMC/5.0 (Uncached)");
+	request.setRawHeader("Authorization", "Client-ID 5b97b0713fba4a3");
+	request.setRawHeader("Accept", "application/json");
+
+	QFile f(m_shot->m_file.absoluteFilePath());
+	if (!f.open(QFile::ReadOnly))
+	{
+		emit failed(m_index_within_job);
+		return;
+	}
+
+	QHttpMultiPart *multipart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
+	QHttpPart filePart;
+	filePart.setBody(f.readAll().toBase64());
+	filePart.setHeader(QNetworkRequest::ContentTypeHeader, "image/png");
+	filePart.setHeader(QNetworkRequest::ContentDispositionHeader, "form-data; name=\"image\"");
+	multipart->append(filePart);
+	QHttpPart typePart;
+	typePart.setHeader(QNetworkRequest::ContentDispositionHeader, "form-data; name=\"type\"");
+	typePart.setBody("base64");
+	multipart->append(typePart);
+	QHttpPart namePart;
+	namePart.setHeader(QNetworkRequest::ContentDispositionHeader, "form-data; name=\"name\"");
+	namePart.setBody(m_shot->m_file.baseName().toUtf8());
+	multipart->append(namePart);
+
+	auto worker = ENV.qnam();
+	QNetworkReply *rep = worker->post(request, multipart);
+
+	m_reply.reset(rep);
+	connect(rep, &QNetworkReply::uploadProgress, this, &ImgurUpload::downloadProgress);
+	connect(rep, &QNetworkReply::finished, this, &ImgurUpload::downloadFinished);
+	connect(rep, SIGNAL(error(QNetworkReply::NetworkError)),
+			SLOT(downloadError(QNetworkReply::NetworkError)));
+}
+void ImgurUpload::downloadError(QNetworkReply::NetworkError error)
+{
+	qCritical() << "ImgurUpload failed with error" << m_reply->errorString() << "Server reply:\n" << m_reply->readAll();
+	if(finished)
+	{
+		qCritical() << "Double finished ImgurUpload!";
+		return;
+	}
+	m_status = Job_Failed;
+	finished = true;
+	m_reply.reset();
+	emit failed(m_index_within_job);
+}
+void ImgurUpload::downloadFinished()
+{
+	if(finished)
+	{
+		qCritical() << "Double finished ImgurUpload!";
+		return;
+	}
+	QByteArray data = m_reply->readAll();
+	m_reply.reset();
+	QJsonParseError jsonError;
+	QJsonDocument doc = QJsonDocument::fromJson(data, &jsonError);
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		qDebug() << "imgur server did not reply with JSON" << jsonError.errorString();
+		finished = true;
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		return;
+	}
+	auto object = doc.object();
+	if (!object.value("success").toBool())
+	{
+		qDebug() << "Screenshot upload not successful:" << doc.toJson();
+		finished = true;
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		return;
+	}
+	m_shot->m_imgurId = object.value("data").toObject().value("id").toString();
+	m_shot->m_url = object.value("data").toObject().value("link").toString();
+	m_status = Job_Finished;
+	finished = true;
+	emit succeeded(m_index_within_job);
+	return;
+}
+void ImgurUpload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
+{
+	m_total_progress = bytesTotal;
+	m_progress = bytesReceived;
+	emit netActionProgress(m_index_within_job, bytesReceived, bytesTotal);
+}
diff --git a/libraries/logic/screenshots/ImgurUpload.h b/libraries/logic/screenshots/ImgurUpload.h
new file mode 100644
index 00000000..0a766b8f
--- /dev/null
+++ b/libraries/logic/screenshots/ImgurUpload.h
@@ -0,0 +1,33 @@
+#pragma once
+#include "net/NetAction.h"
+#include "Screenshot.h"
+
+#include "multimc_logic_export.h"
+
+typedef std::shared_ptr<class ImgurUpload> ImgurUploadPtr;
+class MULTIMC_LOGIC_EXPORT ImgurUpload : public NetAction
+{
+public:
+	explicit ImgurUpload(ScreenshotPtr shot);
+	static ImgurUploadPtr make(ScreenshotPtr shot)
+	{
+		return ImgurUploadPtr(new ImgurUpload(shot));
+	}
+
+protected
+slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	virtual void downloadError(QNetworkReply::NetworkError error);
+	virtual void downloadFinished();
+	virtual void downloadReadyRead()
+	{
+	}
+
+public
+slots:
+	virtual void start();
+
+private:
+	ScreenshotPtr m_shot;
+	bool finished = true;
+};
diff --git a/libraries/logic/screenshots/Screenshot.h b/libraries/logic/screenshots/Screenshot.h
new file mode 100644
index 00000000..b48cbe99
--- /dev/null
+++ b/libraries/logic/screenshots/Screenshot.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <QDateTime>
+#include <QString>
+#include <QFileInfo>
+#include <memory>
+
+struct ScreenShot
+{
+	ScreenShot(QFileInfo file)
+	{
+		m_file = file;
+	}
+	QFileInfo m_file;
+	QString m_url;
+	QString m_imgurId;
+};
+
+typedef std::shared_ptr<ScreenShot> ScreenshotPtr;
diff --git a/libraries/logic/settings/INIFile.cpp b/libraries/logic/settings/INIFile.cpp
new file mode 100644
index 00000000..69a6b87e
--- /dev/null
+++ b/libraries/logic/settings/INIFile.cpp
@@ -0,0 +1,151 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "settings/INIFile.h"
+#include <FileSystem.h>
+
+#include <QFile>
+#include <QTextStream>
+#include <QStringList>
+#include <QSaveFile>
+#include <QDebug>
+
+INIFile::INIFile()
+{
+}
+
+QString INIFile::unescape(QString orig)
+{
+	QString out;
+	QChar prev = 0;
+	for(auto c: orig)
+	{
+		if(prev == '\\')
+		{
+			if(c == 'n')
+				out += '\n';
+			else if (c == 't')
+				out += '\t';
+			else
+				out += c;
+			prev = 0;
+		}
+		else
+		{
+			if(c == '\\')
+			{
+				prev = c;
+				continue;
+			}
+			out += c;
+			prev = 0;
+		}
+	}
+	return out;
+}
+
+QString INIFile::escape(QString orig)
+{
+	QString out;
+	for(auto c: orig)
+	{
+		if(c == '\n')
+			out += "\\n";
+		else if (c == '\t')
+			out += "\\t";
+		else if(c == '\\')
+			out += "\\\\";
+		else
+			out += c;
+	}
+	return out;
+}
+
+bool INIFile::saveFile(QString fileName)
+{
+	QByteArray outArray;
+	for (Iterator iter = begin(); iter != end(); iter++)
+	{
+		QString value = iter.value().toString();
+		value = escape(value);
+		outArray.append(iter.key().toUtf8());
+		outArray.append('=');
+		outArray.append(value.toUtf8());
+		outArray.append('\n');
+	}
+
+	try
+	{
+		FS::write(fileName, outArray);
+	}
+	catch (Exception & e)
+	{
+		qCritical() << e.what();
+		return false;
+	}
+
+	return true;
+}
+
+
+bool INIFile::loadFile(QString fileName)
+{
+	QFile file(fileName);
+	if (!file.open(QIODevice::ReadOnly))
+		return false;
+	bool success = loadFile(file.readAll());
+	file.close();
+	return success;
+}
+
+bool INIFile::loadFile(QByteArray file)
+{
+	QTextStream in(file);
+	in.setCodec("UTF-8");
+
+	QStringList lines = in.readAll().split('\n');
+	for (int i = 0; i < lines.count(); i++)
+	{
+		QString &lineRaw = lines[i];
+		// Ignore comments.
+		QString line = lineRaw.left(lineRaw.indexOf('#')).trimmed();
+
+		int eqPos = line.indexOf('=');
+		if (eqPos == -1)
+			continue;
+		QString key = line.left(eqPos).trimmed();
+		QString valueStr = line.right(line.length() - eqPos - 1).trimmed();
+
+		valueStr = unescape(valueStr);
+
+		QVariant value(valueStr);
+		this->operator[](key) = value;
+	}
+
+	return true;
+}
+
+QVariant INIFile::get(QString key, QVariant def) const
+{
+	if (!this->contains(key))
+		return def;
+	else
+		return this->operator[](key);
+}
+
+void INIFile::set(QString key, QVariant val)
+{
+	this->operator[](key) = val;
+}
diff --git a/libraries/logic/settings/INIFile.h b/libraries/logic/settings/INIFile.h
new file mode 100644
index 00000000..5013eb2d
--- /dev/null
+++ b/libraries/logic/settings/INIFile.h
@@ -0,0 +1,38 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QVariant>
+#include <QIODevice>
+
+#include "multimc_logic_export.h"
+
+// Sectionless INI parser (for instance config files)
+class MULTIMC_LOGIC_EXPORT INIFile : public QMap<QString, QVariant>
+{
+public:
+	explicit INIFile();
+
+	bool loadFile(QByteArray file);
+	bool loadFile(QString fileName);
+	bool saveFile(QString fileName);
+
+	QVariant get(QString key, QVariant def) const;
+	void set(QString key, QVariant val);
+	static QString unescape(QString orig);
+	static QString escape(QString orig);
+};
diff --git a/libraries/logic/settings/INISettingsObject.cpp b/libraries/logic/settings/INISettingsObject.cpp
new file mode 100644
index 00000000..5ccc7446
--- /dev/null
+++ b/libraries/logic/settings/INISettingsObject.cpp
@@ -0,0 +1,107 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "INISettingsObject.h"
+#include "Setting.h"
+
+INISettingsObject::INISettingsObject(const QString &path, QObject *parent)
+	: SettingsObject(parent)
+{
+	m_filePath = path;
+	m_ini.loadFile(path);
+}
+
+void INISettingsObject::setFilePath(const QString &filePath)
+{
+	m_filePath = filePath;
+}
+
+bool INISettingsObject::reload()
+{
+	return m_ini.loadFile(m_filePath) && SettingsObject::reload();
+}
+
+void INISettingsObject::suspendSave()
+{
+	m_suspendSave = true;
+}
+
+void INISettingsObject::resumeSave()
+{
+	m_suspendSave = false;
+	if(m_doSave)
+	{
+		m_ini.saveFile(m_filePath);
+	}
+}
+
+void INISettingsObject::changeSetting(const Setting &setting, QVariant value)
+{
+	if (contains(setting.id()))
+	{
+		// valid value -> set the main config, remove all the sysnonyms
+		if (value.isValid())
+		{
+			auto list = setting.configKeys();
+			m_ini.set(list.takeFirst(), value);
+			for(auto iter: list)
+				m_ini.remove(iter);
+		}
+		// invalid -> remove all (just like resetSetting)
+		else
+		{
+			for(auto iter: setting.configKeys())
+				m_ini.remove(iter);
+		}
+		doSave();
+	}
+}
+
+void INISettingsObject::doSave()
+{
+	if(m_suspendSave)
+	{
+		m_doSave = true;
+	}
+	else
+	{
+		m_ini.saveFile(m_filePath);
+	}
+}
+
+void INISettingsObject::resetSetting(const Setting &setting)
+{
+	// if we have the setting, remove all the synonyms. ALL OF THEM
+	if (contains(setting.id()))
+	{
+		for(auto iter: setting.configKeys())
+			m_ini.remove(iter);
+		doSave();
+	}
+}
+
+QVariant INISettingsObject::retrieveValue(const Setting &setting)
+{
+	// if we have the setting, return value of the first matching synonym
+	if (contains(setting.id()))
+	{
+		for(auto iter: setting.configKeys())
+		{
+			if(m_ini.contains(iter))
+				return m_ini[iter];
+		}
+	}
+	return QVariant();
+}
diff --git a/libraries/logic/settings/INISettingsObject.h b/libraries/logic/settings/INISettingsObject.h
new file mode 100644
index 00000000..4afa2a2c
--- /dev/null
+++ b/libraries/logic/settings/INISettingsObject.h
@@ -0,0 +1,66 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+
+#include "settings/INIFile.h"
+
+#include "settings/SettingsObject.h"
+
+#include "multimc_logic_export.h"
+
+/*!
+ * \brief A settings object that stores its settings in an INIFile.
+ */
+class MULTIMC_LOGIC_EXPORT INISettingsObject : public SettingsObject
+{
+	Q_OBJECT
+public:
+	explicit INISettingsObject(const QString &path, QObject *parent = 0);
+
+	/*!
+	 * \brief Gets the path to the INI file.
+	 * \return The path to the INI file.
+	 */
+	virtual QString filePath() const
+	{
+		return m_filePath;
+	}
+
+	/*!
+	 * \brief Sets the path to the INI file and reloads it.
+	 * \param filePath The INI file's new path.
+	 */
+	virtual void setFilePath(const QString &filePath);
+
+	bool reload() override;
+
+	void suspendSave() override;
+	void resumeSave() override;
+
+protected slots:
+	virtual void changeSetting(const Setting &setting, QVariant value) override;
+	virtual void resetSetting(const Setting &setting) override;
+
+protected:
+	virtual QVariant retrieveValue(const Setting &setting) override;
+	void doSave();
+
+protected:
+	INIFile m_ini;
+	QString m_filePath;
+};
diff --git a/libraries/logic/settings/OverrideSetting.cpp b/libraries/logic/settings/OverrideSetting.cpp
new file mode 100644
index 00000000..25162dff
--- /dev/null
+++ b/libraries/logic/settings/OverrideSetting.cpp
@@ -0,0 +1,54 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "OverrideSetting.h"
+
+OverrideSetting::OverrideSetting(std::shared_ptr<Setting> other, std::shared_ptr<Setting> gate)
+	: Setting(other->configKeys(), QVariant())
+{
+	Q_ASSERT(other);
+	Q_ASSERT(gate);
+	m_other = other;
+	m_gate = gate;
+}
+
+bool OverrideSetting::isOverriding() const
+{
+	return m_gate->get().toBool();
+}
+
+QVariant OverrideSetting::defValue() const
+{
+	return m_other->get();
+}
+
+QVariant OverrideSetting::get() const
+{
+	if(isOverriding())
+	{
+		return Setting::get();
+	}
+	return m_other->get();
+}
+
+void OverrideSetting::reset()
+{
+	Setting::reset();
+}
+
+void OverrideSetting::set(QVariant value)
+{
+	Setting::set(value);
+}
diff --git a/libraries/logic/settings/OverrideSetting.h b/libraries/logic/settings/OverrideSetting.h
new file mode 100644
index 00000000..68595cde
--- /dev/null
+++ b/libraries/logic/settings/OverrideSetting.h
@@ -0,0 +1,46 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <memory>
+
+#include "Setting.h"
+
+/*!
+ * \brief A setting that 'overrides another.'
+ * This means that the setting's default value will be the value of another setting.
+ * The other setting can be (and usually is) a part of a different SettingsObject
+ * than this one.
+ */
+class OverrideSetting : public Setting
+{
+	Q_OBJECT
+public:
+	explicit OverrideSetting(std::shared_ptr<Setting> overriden, std::shared_ptr<Setting> gate);
+
+	virtual QVariant defValue() const;
+	virtual QVariant get() const;
+	virtual void set (QVariant value);
+	virtual void reset();
+
+private:
+	bool isOverriding() const;
+
+protected:
+	std::shared_ptr<Setting> m_other;
+	std::shared_ptr<Setting> m_gate;
+};
diff --git a/libraries/logic/settings/PassthroughSetting.cpp b/libraries/logic/settings/PassthroughSetting.cpp
new file mode 100644
index 00000000..45a560de
--- /dev/null
+++ b/libraries/logic/settings/PassthroughSetting.cpp
@@ -0,0 +1,66 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "PassthroughSetting.h"
+
+PassthroughSetting::PassthroughSetting(std::shared_ptr<Setting> other, std::shared_ptr<Setting> gate)
+	: Setting(other->configKeys(), QVariant())
+{
+	Q_ASSERT(other);
+	Q_ASSERT(gate);
+	m_other = other;
+	m_gate = gate;
+}
+
+bool PassthroughSetting::isOverriding() const
+{
+	return m_gate->get().toBool();
+}
+
+QVariant PassthroughSetting::defValue() const
+{
+	if(isOverriding())
+	{
+		return m_other->get();
+	}
+	return m_other->defValue();
+}
+
+QVariant PassthroughSetting::get() const
+{
+	if(isOverriding())
+	{
+		return Setting::get();
+	}
+	return m_other->get();
+}
+
+void PassthroughSetting::reset()
+{
+	if(isOverriding())
+	{
+		Setting::reset();
+	}
+	m_other->reset();
+}
+
+void PassthroughSetting::set(QVariant value)
+{
+	if(isOverriding())
+	{
+		Setting::set(value);
+	}
+	m_other->set(value);
+}
diff --git a/libraries/logic/settings/PassthroughSetting.h b/libraries/logic/settings/PassthroughSetting.h
new file mode 100644
index 00000000..c4dc646c
--- /dev/null
+++ b/libraries/logic/settings/PassthroughSetting.h
@@ -0,0 +1,45 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <memory>
+
+#include "Setting.h"
+
+/*!
+ * \brief A setting that 'overrides another.' based on the value of a 'gate' setting
+ * If 'gate' evaluates to true, the override stores and returns data
+ * If 'gate' evaluates to false, the original does,
+ */
+class PassthroughSetting : public Setting
+{
+	Q_OBJECT
+public:
+	explicit PassthroughSetting(std::shared_ptr<Setting> overriden, std::shared_ptr<Setting> gate);
+
+	virtual QVariant defValue() const;
+	virtual QVariant get() const;
+	virtual void set (QVariant value);
+	virtual void reset();
+
+private:
+	bool isOverriding() const;
+
+protected:
+	std::shared_ptr<Setting> m_other;
+	std::shared_ptr<Setting> m_gate;
+};
diff --git a/libraries/logic/settings/Setting.cpp b/libraries/logic/settings/Setting.cpp
new file mode 100644
index 00000000..b17101a2
--- /dev/null
+++ b/libraries/logic/settings/Setting.cpp
@@ -0,0 +1,53 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Setting.h"
+#include "settings/SettingsObject.h"
+
+Setting::Setting(QStringList synonyms, QVariant defVal)
+	: QObject(), m_synonyms(synonyms), m_defVal(defVal)
+{
+}
+
+QVariant Setting::get() const
+{
+	SettingsObject *sbase = m_storage;
+	if (!sbase)
+	{
+		return defValue();
+	}
+	else
+	{
+		QVariant test = sbase->retrieveValue(*this);
+		if (!test.isValid())
+			return defValue();
+		return test;
+	}
+}
+
+QVariant Setting::defValue() const
+{
+	return m_defVal;
+}
+
+void Setting::set(QVariant value)
+{
+	emit SettingChanged(*this, value);
+}
+
+void Setting::reset()
+{
+	emit settingReset(*this);
+}
diff --git a/libraries/logic/settings/Setting.h b/libraries/logic/settings/Setting.h
new file mode 100644
index 00000000..6d53ac6d
--- /dev/null
+++ b/libraries/logic/settings/Setting.h
@@ -0,0 +1,119 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QVariant>
+#include <QStringList>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class SettingsObject;
+
+/*!
+ *
+ */
+class MULTIMC_LOGIC_EXPORT Setting : public QObject
+{
+	Q_OBJECT
+public:
+	/**
+	 * Construct a Setting
+	 *
+	 * Synonyms are all the possible names used in the settings object, in order of preference.
+	 * First synonym is the ID, which identifies the setting in MultiMC.
+	 *
+	 * defVal is the default value that will be returned when the settings object
+	 * doesn't have any value for this setting.
+	 */
+	explicit Setting(QStringList synonyms, QVariant defVal = QVariant());
+
+	/*!
+	 * \brief Gets this setting's ID.
+	 * This is used to refer to the setting within the application.
+	 * \warning Changing the ID while the setting is registered with a SettingsObject results in
+	 * undefined behavior.
+	 * \return The ID of the setting.
+	 */
+	virtual QString id() const
+	{
+		return m_synonyms.first();
+	}
+
+	/*!
+	 * \brief Gets this setting's config file key.
+	 * This is used to store the setting's value in the config file. It is usually
+	 * the same as the setting's ID, but it can be different.
+	 * \return The setting's config file key.
+	 */
+	virtual QStringList configKeys() const
+	{
+		return m_synonyms;
+	}
+
+	/*!
+	 * \brief Gets this setting's value as a QVariant.
+	 * This is done by calling the SettingsObject's retrieveValue() function.
+	 * If this Setting doesn't have a SettingsObject, this returns an invalid QVariant.
+	 * \return QVariant containing this setting's value.
+	 * \sa value()
+	 */
+	virtual QVariant get() const;
+
+	/*!
+	 * \brief Gets this setting's default value.
+	 * \return The default value of this setting.
+	 */
+	virtual QVariant defValue() const;
+
+signals:
+	/*!
+	 * \brief Signal emitted when this Setting object's value changes.
+	 * \param setting A reference to the Setting that changed.
+	 * \param value This Setting object's new value.
+	 */
+	void SettingChanged(const Setting &setting, QVariant value);
+
+	/*!
+	 * \brief Signal emitted when this Setting object's value resets to default.
+	 * \param setting A reference to the Setting that changed.
+	 */
+	void settingReset(const Setting &setting);
+
+public
+slots:
+	/*!
+	 * \brief Changes the setting's value.
+	 * This is done by emitting the SettingChanged() signal which will then be
+	 * handled by the SettingsObject object and cause the setting to change.
+	 * \param value The new value.
+	 */
+	virtual void set(QVariant value);
+
+	/*!
+	 * \brief Reset the setting to default
+	 * This is done by emitting the settingReset() signal which will then be
+	 * handled by the SettingsObject object and cause the setting to change.
+	 */
+	virtual void reset();
+
+protected:
+	friend class SettingsObject;
+	SettingsObject * m_storage;
+	QStringList m_synonyms;
+	QVariant m_defVal;
+};
diff --git a/libraries/logic/settings/SettingsObject.cpp b/libraries/logic/settings/SettingsObject.cpp
new file mode 100644
index 00000000..f2ffdf9b
--- /dev/null
+++ b/libraries/logic/settings/SettingsObject.cpp
@@ -0,0 +1,142 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "settings/SettingsObject.h"
+#include "settings/Setting.h"
+#include "settings/OverrideSetting.h"
+#include "PassthroughSetting.h"
+#include <QDebug>
+
+#include <QVariant>
+
+SettingsObject::SettingsObject(QObject *parent) : QObject(parent)
+{
+}
+
+SettingsObject::~SettingsObject()
+{
+	m_settings.clear();
+}
+
+std::shared_ptr<Setting> SettingsObject::registerOverride(std::shared_ptr<Setting> original,
+														  std::shared_ptr<Setting> gate)
+{
+	if (contains(original->id()))
+	{
+		qCritical() << QString("Failed to register setting %1. ID already exists.")
+				   .arg(original->id());
+		return nullptr; // Fail
+	}
+	auto override = std::make_shared<OverrideSetting>(original, gate);
+	override->m_storage = this;
+	connectSignals(*override);
+	m_settings.insert(override->id(), override);
+	return override;
+}
+
+std::shared_ptr<Setting> SettingsObject::registerPassthrough(std::shared_ptr<Setting> original,
+															 std::shared_ptr<Setting> gate)
+{
+	if (contains(original->id()))
+	{
+		qCritical() << QString("Failed to register setting %1. ID already exists.")
+				   .arg(original->id());
+		return nullptr; // Fail
+	}
+	auto passthrough = std::make_shared<PassthroughSetting>(original, gate);
+	passthrough->m_storage = this;
+	connectSignals(*passthrough);
+	m_settings.insert(passthrough->id(), passthrough);
+	return passthrough;
+}
+
+std::shared_ptr<Setting> SettingsObject::registerSetting(QStringList synonyms, QVariant defVal)
+{
+	if (synonyms.empty())
+		return nullptr;
+	if (contains(synonyms.first()))
+	{
+		qCritical() << QString("Failed to register setting %1. ID already exists.")
+				   .arg(synonyms.first());
+		return nullptr; // Fail
+	}
+	auto setting = std::make_shared<Setting>(synonyms, defVal);
+	setting->m_storage = this;
+	connectSignals(*setting);
+	m_settings.insert(setting->id(), setting);
+	return setting;
+}
+
+std::shared_ptr<Setting> SettingsObject::getSetting(const QString &id) const
+{
+	// Make sure there is a setting with the given ID.
+	if (!m_settings.contains(id))
+		return NULL;
+
+	return m_settings[id];
+}
+
+QVariant SettingsObject::get(const QString &id) const
+{
+	auto setting = getSetting(id);
+	return (setting ? setting->get() : QVariant());
+}
+
+bool SettingsObject::set(const QString &id, QVariant value)
+{
+	auto setting = getSetting(id);
+	if (!setting)
+	{
+		qCritical() << QString("Error changing setting %1. Setting doesn't exist.").arg(id);
+		return false;
+	}
+	else
+	{
+		setting->set(value);
+		return true;
+	}
+}
+
+void SettingsObject::reset(const QString &id) const
+{
+	auto setting = getSetting(id);
+	if (setting)
+		setting->reset();
+}
+
+bool SettingsObject::contains(const QString &id)
+{
+	return m_settings.contains(id);
+}
+
+bool SettingsObject::reload()
+{
+	for (auto setting : m_settings.values())
+	{
+		setting->set(setting->get());
+	}
+	return true;
+}
+
+void SettingsObject::connectSignals(const Setting &setting)
+{
+	connect(&setting, SIGNAL(SettingChanged(const Setting &, QVariant)),
+			SLOT(changeSetting(const Setting &, QVariant)));
+	connect(&setting, SIGNAL(SettingChanged(const Setting &, QVariant)),
+			SIGNAL(SettingChanged(const Setting &, QVariant)));
+
+	connect(&setting, SIGNAL(settingReset(Setting)), SLOT(resetSetting(const Setting &)));
+	connect(&setting, SIGNAL(settingReset(Setting)), SIGNAL(settingReset(const Setting &)));
+}
diff --git a/libraries/logic/settings/SettingsObject.h b/libraries/logic/settings/SettingsObject.h
new file mode 100644
index 00000000..82193903
--- /dev/null
+++ b/libraries/logic/settings/SettingsObject.h
@@ -0,0 +1,214 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QMap>
+#include <QStringList>
+#include <QVariant>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class Setting;
+class SettingsObject;
+
+typedef std::shared_ptr<SettingsObject> SettingsObjectPtr;
+
+/*!
+ * \brief The SettingsObject handles communicating settings between the application and a
+ *settings file.
+ * The class keeps a list of Setting objects. Each Setting object represents one
+ * of the application's settings. These Setting objects are registered with
+ * a SettingsObject and can be managed similarly to the way a list works.
+ *
+ * \author Andrew Okin
+ * \date 2/22/2013
+ *
+ * \sa Setting
+ */
+class MULTIMC_LOGIC_EXPORT SettingsObject : public QObject
+{
+	Q_OBJECT
+public:
+	class Lock
+	{
+	public:
+		Lock(SettingsObjectPtr locked)
+			:m_locked(locked)
+		{
+			m_locked->suspendSave();
+		}
+		~Lock()
+		{
+			m_locked->resumeSave();
+		}
+	private:
+		SettingsObjectPtr m_locked;
+	};
+public:
+	explicit SettingsObject(QObject *parent = 0);
+	virtual ~SettingsObject();
+	/*!
+	 * Registers an override setting for the given original setting in this settings object
+	 * gate decides if the passthrough (true) or the original (false) is used for value
+	 *
+	 * This will fail if there is already a setting with the same ID as
+	 * the one that is being registered.
+	 * \return A valid Setting shared pointer if successful.
+	 */
+	std::shared_ptr<Setting> registerOverride(std::shared_ptr<Setting> original, std::shared_ptr<Setting> gate);
+
+	/*!
+	 * Registers a passthorugh setting for the given original setting in this settings object
+	 * gate decides if the passthrough (true) or the original (false) is used for value
+	 *
+	 * This will fail if there is already a setting with the same ID as
+	 * the one that is being registered.
+	 * \return A valid Setting shared pointer if successful.
+	 */
+	std::shared_ptr<Setting> registerPassthrough(std::shared_ptr<Setting> original, std::shared_ptr<Setting> gate);
+
+	/*!
+	 * Registers the given setting with this SettingsObject and connects the necessary  signals.
+	 *
+	 * This will fail if there is already a setting with the same ID as
+	 * the one that is being registered.
+	 * \return A valid Setting shared pointer if successful.
+	 */
+	std::shared_ptr<Setting> registerSetting(QStringList synonyms,
+											 QVariant defVal = QVariant());
+
+	/*!
+	 * Registers the given setting with this SettingsObject and connects the necessary signals.
+	 *
+	 * This will fail if there is already a setting with the same ID as
+	 * the one that is being registered.
+	 * \return A valid Setting shared pointer if successful.
+	 */
+	std::shared_ptr<Setting> registerSetting(QString id, QVariant defVal = QVariant())
+	{
+		return registerSetting(QStringList(id), defVal);
+	}
+
+	/*!
+	 * \brief Gets the setting with the given ID.
+	 * \param id The ID of the setting to get.
+	 * \return A pointer to the setting with the given ID.
+	 * Returns null if there is no setting with the given ID.
+	 * \sa operator []()
+	 */
+	std::shared_ptr<Setting> getSetting(const QString &id) const;
+
+	/*!
+	 * \brief Gets the value of the setting with the given ID.
+	 * \param id The ID of the setting to get.
+	 * \return The setting's value as a QVariant.
+	 * If no setting with the given ID exists, returns an invalid QVariant.
+	 */
+	QVariant get(const QString &id) const;
+
+	/*!
+	 * \brief Sets the value of the setting with the given ID.
+	 * If no setting with the given ID exists, returns false
+	 * \param id The ID of the setting to change.
+	 * \param value The new value of the setting.
+	 * \return True if successful, false if it failed.
+	 */
+	bool set(const QString &id, QVariant value);
+
+	/*!
+	 * \brief Reverts the setting with the given ID to default.
+	 * \param id The ID of the setting to reset.
+	 */
+	void reset(const QString &id) const;
+
+	/*!
+	 * \brief Checks if this SettingsObject contains a setting with the given ID.
+	 * \param id The ID to check for.
+	 * \return True if the SettingsObject has a setting with the given ID.
+	 */
+	bool contains(const QString &id);
+
+	/*!
+	 * \brief Reloads the settings and emit signals for changed settings
+	 * \return True if reloading was successful
+	 */
+	virtual bool reload();
+
+	virtual void suspendSave() = 0;
+	virtual void resumeSave() = 0;
+signals:
+	/*!
+	 * \brief Signal emitted when one of this SettingsObject object's settings changes.
+	 * This is usually just connected directly to each Setting object's
+	 * SettingChanged() signals.
+	 * \param setting A reference to the Setting object that changed.
+	 * \param value The Setting object's new value.
+	 */
+	void SettingChanged(const Setting &setting, QVariant value);
+
+	/*!
+	 * \brief Signal emitted when one of this SettingsObject object's settings resets.
+	 * This is usually just connected directly to each Setting object's
+	 * settingReset() signals.
+	 * \param setting A reference to the Setting object that changed.
+	 */
+	void settingReset(const Setting &setting);
+
+protected
+slots:
+	/*!
+	 * \brief Changes a setting.
+	 * This slot is usually connected to each Setting object's
+	 * SettingChanged() signal. The signal is emitted, causing this slot
+	 * to update the setting's value in the config file.
+	 * \param setting A reference to the Setting object that changed.
+	 * \param value The setting's new value.
+	 */
+	virtual void changeSetting(const Setting &setting, QVariant value) = 0;
+
+	/*!
+	 * \brief Resets a setting.
+	 * This slot is usually connected to each Setting object's
+	 * settingReset() signal. The signal is emitted, causing this slot
+	 * to update the setting's value in the config file.
+	 * \param setting A reference to the Setting object that changed.
+	 */
+	virtual void resetSetting(const Setting &setting) = 0;
+
+protected:
+	/*!
+	 * \brief Connects the necessary signals to the given Setting.
+	 * \param setting The setting to connect.
+	 */
+	void connectSignals(const Setting &setting);
+
+	/*!
+	 * \brief Function used by Setting objects to get their values from the SettingsObject.
+	 * \param setting The
+	 * \return
+	 */
+	virtual QVariant retrieveValue(const Setting &setting) = 0;
+
+	friend class Setting;
+
+private:
+	QMap<QString, std::shared_ptr<Setting>> m_settings;
+protected:
+	bool m_suspendSave = false;
+	bool m_doSave = false;
+};
diff --git a/libraries/logic/status/StatusChecker.cpp b/libraries/logic/status/StatusChecker.cpp
new file mode 100644
index 00000000..13cac037
--- /dev/null
+++ b/libraries/logic/status/StatusChecker.cpp
@@ -0,0 +1,153 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "StatusChecker.h"
+
+#include <net/URLConstants.h>
+
+#include <QByteArray>
+
+#include <QDebug>
+
+StatusChecker::StatusChecker()
+{
+
+}
+
+void StatusChecker::timerEvent(QTimerEvent *e)
+{
+	QObject::timerEvent(e);
+	reloadStatus();
+}
+
+void StatusChecker::reloadStatus()
+{
+	if (isLoadingStatus())
+	{
+		// qDebug() << "Ignored request to reload status. Currently reloading already.";
+		return;
+	}
+
+	// qDebug() << "Reloading status.";
+
+	NetJob* job = new NetJob("Status JSON");
+	job->addNetAction(ByteArrayDownload::make(URLConstants::MOJANG_STATUS_URL));
+	QObject::connect(job, &NetJob::succeeded, this, &StatusChecker::statusDownloadFinished);
+	QObject::connect(job, &NetJob::failed, this, &StatusChecker::statusDownloadFailed);
+	m_statusNetJob.reset(job);
+	emit statusLoading(true);
+	job->start();
+}
+
+void StatusChecker::statusDownloadFinished()
+{
+	qDebug() << "Finished loading status JSON.";
+	m_statusEntries.clear();
+	QByteArray data;
+	{
+		ByteArrayDownloadPtr dl = std::dynamic_pointer_cast<ByteArrayDownload>(m_statusNetJob->first());
+		data = dl->m_data;
+		m_statusNetJob.reset();
+	}
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		fail("Error parsing status JSON:" + jsonError.errorString());
+		return;
+	}
+
+	if (!jsonDoc.isArray())
+	{
+		fail("Error parsing status JSON: JSON root is not an array");
+		return;
+	}
+
+	QJsonArray root = jsonDoc.array();
+
+	for(auto status = root.begin(); status != root.end(); ++status)
+	{
+		QVariantMap map = (*status).toObject().toVariantMap();
+
+		for (QVariantMap::const_iterator iter = map.begin(); iter != map.end(); ++iter)
+		{
+			QString key = iter.key();
+			QVariant value = iter.value();
+
+			if(value.type() == QVariant::Type::String)
+			{
+				m_statusEntries.insert(key, value.toString());
+				//qDebug() << "Status JSON object: " << key << m_statusEntries[key];
+			}
+			else
+			{
+				fail("Malformed status JSON: expected status type to be a string.");
+				return;
+			}
+		}
+	}
+
+	succeed();
+}
+
+void StatusChecker::statusDownloadFailed(QString reason)
+{
+	fail(tr("Failed to load status JSON:\n%1").arg(reason));
+}
+
+
+QMap<QString, QString> StatusChecker::getStatusEntries() const
+{
+	return m_statusEntries;
+}
+
+bool StatusChecker::isLoadingStatus() const
+{
+	return m_statusNetJob.get() != nullptr;
+}
+
+QString StatusChecker::getLastLoadErrorMsg() const
+{
+	return m_lastLoadError;
+}
+
+void StatusChecker::succeed()
+{
+	if(m_prevEntries != m_statusEntries)
+	{
+		emit statusChanged(m_statusEntries);
+		m_prevEntries = m_statusEntries;
+	}
+	m_lastLoadError = "";
+	qDebug() << "Status loading succeeded.";
+	m_statusNetJob.reset();
+	emit statusLoading(false);
+}
+
+void StatusChecker::fail(const QString& errorMsg)
+{
+	if(m_prevEntries != m_statusEntries)
+	{
+		emit statusChanged(m_statusEntries);
+		m_prevEntries = m_statusEntries;
+	}
+	m_lastLoadError = errorMsg;
+	qDebug() << "Failed to load status:" << errorMsg;
+	m_statusNetJob.reset();
+	emit statusLoading(false);
+}
+
diff --git a/libraries/logic/status/StatusChecker.h b/libraries/logic/status/StatusChecker.h
new file mode 100644
index 00000000..c1a54dba
--- /dev/null
+++ b/libraries/logic/status/StatusChecker.h
@@ -0,0 +1,60 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QString>
+#include <QList>
+
+#include <net/NetJob.h>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT StatusChecker : public QObject
+{
+	Q_OBJECT
+public:
+	StatusChecker();
+
+	QString getLastLoadErrorMsg() const;
+
+	bool isLoadingStatus() const;
+
+	QMap<QString, QString> getStatusEntries() const;
+
+	void Q_SLOT reloadStatus();
+
+protected:
+	virtual void timerEvent(QTimerEvent *);
+
+signals:
+	void statusLoading(bool loading);
+	void statusChanged(QMap<QString, QString> newStatus);
+
+protected slots:
+	void statusDownloadFinished();
+	void statusDownloadFailed(QString reason);
+
+protected:
+	QMap<QString, QString> m_prevEntries;
+	QMap<QString, QString> m_statusEntries;
+	NetJobPtr m_statusNetJob;
+	QString m_lastLoadError;
+
+	void Q_SLOT succeed();
+	void Q_SLOT fail(const QString& errorMsg);
+};
+
diff --git a/libraries/logic/tasks/SequentialTask.cpp b/libraries/logic/tasks/SequentialTask.cpp
new file mode 100644
index 00000000..ac0e7820
--- /dev/null
+++ b/libraries/logic/tasks/SequentialTask.cpp
@@ -0,0 +1,55 @@
+#include "SequentialTask.h"
+
+SequentialTask::SequentialTask(QObject *parent) : Task(parent), m_currentIndex(-1)
+{
+}
+
+void SequentialTask::addTask(std::shared_ptr<Task> task)
+{
+	m_queue.append(task);
+}
+
+void SequentialTask::executeTask()
+{
+	m_currentIndex = -1;
+	startNext();
+}
+
+void SequentialTask::startNext()
+{
+	if (m_currentIndex != -1)
+	{
+		std::shared_ptr<Task> previous = m_queue[m_currentIndex];
+		disconnect(previous.get(), 0, this, 0);
+	}
+	m_currentIndex++;
+	if (m_queue.isEmpty() || m_currentIndex >= m_queue.size())
+	{
+		emitSucceeded();
+		return;
+	}
+	std::shared_ptr<Task> next = m_queue[m_currentIndex];
+	connect(next.get(), SIGNAL(failed(QString)), this, SLOT(subTaskFailed(QString)));
+	connect(next.get(), SIGNAL(status(QString)), this, SLOT(subTaskStatus(QString)));
+	connect(next.get(), SIGNAL(progress(qint64, qint64)), this, SLOT(subTaskProgress(qint64, qint64)));
+	connect(next.get(), SIGNAL(succeeded()), this, SLOT(startNext()));
+	next->start();
+}
+
+void SequentialTask::subTaskFailed(const QString &msg)
+{
+	emitFailed(msg);
+}
+void SequentialTask::subTaskStatus(const QString &msg)
+{
+	setStatus(msg);
+}
+void SequentialTask::subTaskProgress(qint64 current, qint64 total)
+{
+	if(total == 0)
+	{
+		setProgress(0, 100);
+		return;
+	}
+	setProgress(current, total);
+}
diff --git a/libraries/logic/tasks/SequentialTask.h b/libraries/logic/tasks/SequentialTask.h
new file mode 100644
index 00000000..69031095
--- /dev/null
+++ b/libraries/logic/tasks/SequentialTask.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "Task.h"
+
+#include <QQueue>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT SequentialTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit SequentialTask(QObject *parent = 0);
+
+	void addTask(std::shared_ptr<Task> task);
+
+protected:
+	void executeTask();
+
+private
+slots:
+	void startNext();
+	void subTaskFailed(const QString &msg);
+	void subTaskStatus(const QString &msg);
+	void subTaskProgress(qint64 current, qint64 total);
+
+private:
+	QQueue<std::shared_ptr<Task> > m_queue;
+	int m_currentIndex;
+};
diff --git a/libraries/logic/tasks/Task.cpp b/libraries/logic/tasks/Task.cpp
new file mode 100644
index 00000000..3c4e3188
--- /dev/null
+++ b/libraries/logic/tasks/Task.cpp
@@ -0,0 +1,88 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Task.h"
+
+#include <QDebug>
+
+Task::Task(QObject *parent) : QObject(parent)
+{
+}
+
+void Task::setStatus(const QString &new_status)
+{
+	if(m_status != new_status)
+	{
+		m_status = new_status;
+		emit status(m_status);
+	}
+}
+
+void Task::setProgress(qint64 current, qint64 total)
+{
+	m_progress = current;
+	m_progressTotal = total;
+	emit progress(m_progress, m_progressTotal);
+}
+
+void Task::start()
+{
+	m_running = true;
+	emit started();
+	executeTask();
+}
+
+void Task::emitFailed(QString reason)
+{
+	m_running = false;
+	m_finished = true;
+	m_succeeded = false;
+	m_failReason = reason;
+	qCritical() << "Task failed: " << reason;
+	emit failed(reason);
+	emit finished();
+}
+
+void Task::emitSucceeded()
+{
+	if (!m_running) { return; } // Don't succeed twice.
+	m_running = false;
+	m_finished = true;
+	m_succeeded = true;
+	qDebug() << "Task succeeded";
+	emit succeeded();
+	emit finished();
+}
+
+bool Task::isRunning() const
+{
+	return m_running;
+}
+
+bool Task::isFinished() const
+{
+	return m_finished;
+}
+
+bool Task::successful() const
+{
+	return m_succeeded;
+}
+
+QString Task::failReason() const
+{
+	return m_failReason;
+}
+
diff --git a/libraries/logic/tasks/Task.h b/libraries/logic/tasks/Task.h
new file mode 100644
index 00000000..2b0ccbcd
--- /dev/null
+++ b/libraries/logic/tasks/Task.h
@@ -0,0 +1,96 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QString>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT Task : public QObject
+{
+	Q_OBJECT
+public:
+	explicit Task(QObject *parent = 0);
+	virtual ~Task() {};
+
+	virtual bool isRunning() const;
+
+	virtual bool isFinished() const;
+
+	/*!
+	 * True if this task was successful.
+	 * If the task failed or is still running, returns false.
+	 */
+	virtual bool successful() const;
+
+	/*!
+	 * Returns the string that was passed to emitFailed as the error message when the task failed.
+	 * If the task hasn't failed, returns an empty string.
+	 */
+	virtual QString failReason() const;
+
+	virtual bool canAbort() const { return false; }
+
+	QString getStatus()
+	{
+		return m_status;
+	}
+
+	qint64 getProgress()
+	{
+		return m_progress;
+	}
+
+	qint64 getTotalProgress()
+	{
+		return m_progressTotal;
+	}
+
+signals:
+	void started();
+	void progress(qint64 current, qint64 total);
+	void finished();
+	void succeeded();
+	void failed(QString reason);
+	void status(QString status);
+
+public
+slots:
+	virtual void start();
+	virtual bool abort() { return false; };
+
+protected:
+	virtual void executeTask() = 0;
+
+protected slots:
+	virtual void emitSucceeded();
+	virtual void emitFailed(QString reason);
+
+public slots:
+	void setStatus(const QString &status);
+	void setProgress(qint64 current, qint64 total);
+
+protected:
+	bool m_running = false;
+	bool m_finished = false;
+	bool m_succeeded = false;
+	QString m_failReason = "";
+	QString m_status;
+	int m_progress = 0;
+	int m_progressTotal = 100;
+};
+
diff --git a/libraries/logic/tasks/ThreadTask.cpp b/libraries/logic/tasks/ThreadTask.cpp
new file mode 100644
index 00000000..ddd1dee5
--- /dev/null
+++ b/libraries/logic/tasks/ThreadTask.cpp
@@ -0,0 +1,41 @@
+#include "ThreadTask.h"
+#include <QtConcurrentRun>
+ThreadTask::ThreadTask(Task * internal, QObject *parent) : Task(parent), m_internal(internal)
+{
+}
+
+void ThreadTask::start()
+{
+	connect(m_internal, SIGNAL(failed(QString)), SLOT(iternal_failed(QString)));
+	connect(m_internal, SIGNAL(progress(qint64,qint64)), SLOT(iternal_progress(qint64,qint64)));
+	connect(m_internal, SIGNAL(started()), SLOT(iternal_started()));
+	connect(m_internal, SIGNAL(status(QString)), SLOT(iternal_status(QString)));
+	connect(m_internal, SIGNAL(succeeded()), SLOT(iternal_succeeded()));
+	m_running = true;
+	QtConcurrent::run(m_internal, &Task::start);
+}
+
+void ThreadTask::iternal_failed(QString reason)
+{
+	emitFailed(reason);
+}
+
+void ThreadTask::iternal_progress(qint64 current, qint64 total)
+{
+	progress(current, total);
+}
+
+void ThreadTask::iternal_started()
+{
+	emit started();
+}
+
+void ThreadTask::iternal_status(QString status)
+{
+	setStatus(status);
+}
+
+void ThreadTask::iternal_succeeded()
+{
+	emitSucceeded();
+}
diff --git a/libraries/logic/tasks/ThreadTask.h b/libraries/logic/tasks/ThreadTask.h
new file mode 100644
index 00000000..718dbc91
--- /dev/null
+++ b/libraries/logic/tasks/ThreadTask.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include "Task.h"
+
+class ThreadTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit ThreadTask(Task * internal, QObject * parent = nullptr);
+
+protected:
+	void executeTask() {};
+
+public slots:
+	virtual void start();
+
+private slots:
+	void iternal_started();
+	void iternal_progress(qint64 current, qint64 total);
+	void iternal_succeeded();
+	void iternal_failed(QString reason);
+	void iternal_status(QString status);
+private:
+	Task * m_internal;
+};
\ No newline at end of file
diff --git a/libraries/logic/tools/BaseExternalTool.cpp b/libraries/logic/tools/BaseExternalTool.cpp
new file mode 100644
index 00000000..2b97c3c9
--- /dev/null
+++ b/libraries/logic/tools/BaseExternalTool.cpp
@@ -0,0 +1,41 @@
+#include "BaseExternalTool.h"
+
+#include <QProcess>
+#include <QDir>
+
+#ifdef Q_OS_WIN
+#include <windows.h>
+#endif
+
+#include "BaseInstance.h"
+
+BaseExternalTool::BaseExternalTool(SettingsObjectPtr settings, InstancePtr instance, QObject *parent)
+	: QObject(parent), m_instance(instance), globalSettings(settings)
+{
+}
+
+BaseExternalTool::~BaseExternalTool()
+{
+}
+
+BaseDetachedTool::BaseDetachedTool(SettingsObjectPtr settings, InstancePtr instance, QObject *parent)
+	: BaseExternalTool(settings, instance, parent)
+{
+
+}
+
+void BaseDetachedTool::run()
+{
+	runImpl();
+}
+
+
+BaseExternalToolFactory::~BaseExternalToolFactory()
+{
+}
+
+BaseDetachedTool *BaseDetachedToolFactory::createDetachedTool(InstancePtr instance,
+															  QObject *parent)
+{
+	return qobject_cast<BaseDetachedTool *>(createTool(instance, parent));
+}
diff --git a/libraries/logic/tools/BaseExternalTool.h b/libraries/logic/tools/BaseExternalTool.h
new file mode 100644
index 00000000..fe1b5dc6
--- /dev/null
+++ b/libraries/logic/tools/BaseExternalTool.h
@@ -0,0 +1,60 @@
+#pragma once
+
+#include <QObject>
+#include <BaseInstance.h>
+
+#include "multimc_logic_export.h"
+
+class BaseInstance;
+class SettingsObject;
+class QProcess;
+
+class MULTIMC_LOGIC_EXPORT BaseExternalTool : public QObject
+{
+	Q_OBJECT
+public:
+	explicit BaseExternalTool(SettingsObjectPtr settings, InstancePtr instance, QObject *parent = 0);
+	virtual ~BaseExternalTool();
+
+protected:
+	InstancePtr m_instance;
+	SettingsObjectPtr globalSettings;
+};
+
+class MULTIMC_LOGIC_EXPORT BaseDetachedTool : public BaseExternalTool
+{
+	Q_OBJECT
+public:
+	explicit BaseDetachedTool(SettingsObjectPtr settings, InstancePtr instance, QObject *parent = 0);
+
+public
+slots:
+	void run();
+
+protected:
+	virtual void runImpl() = 0;
+};
+
+class MULTIMC_LOGIC_EXPORT BaseExternalToolFactory
+{
+public:
+	virtual ~BaseExternalToolFactory();
+
+	virtual QString name() const = 0;
+
+	virtual void registerSettings(SettingsObjectPtr settings) = 0;
+
+	virtual BaseExternalTool *createTool(InstancePtr instance, QObject *parent = 0) = 0;
+
+	virtual bool check(QString *error) = 0;
+	virtual bool check(const QString &path, QString *error) = 0;
+
+protected:
+	SettingsObjectPtr globalSettings;
+};
+
+class MULTIMC_LOGIC_EXPORT BaseDetachedToolFactory : public BaseExternalToolFactory
+{
+public:
+	virtual BaseDetachedTool *createDetachedTool(InstancePtr instance, QObject *parent = 0);
+};
diff --git a/libraries/logic/tools/BaseProfiler.cpp b/libraries/logic/tools/BaseProfiler.cpp
new file mode 100644
index 00000000..5ff0fa44
--- /dev/null
+++ b/libraries/logic/tools/BaseProfiler.cpp
@@ -0,0 +1,35 @@
+#include "BaseProfiler.h"
+
+#include <QProcess>
+
+BaseProfiler::BaseProfiler(SettingsObjectPtr settings, InstancePtr instance, QObject *parent)
+	: BaseExternalTool(settings, instance, parent)
+{
+}
+
+void BaseProfiler::beginProfiling(std::shared_ptr<LaunchTask> process)
+{
+	beginProfilingImpl(process);
+}
+
+void BaseProfiler::abortProfiling()
+{
+	abortProfilingImpl();
+}
+
+void BaseProfiler::abortProfilingImpl()
+{
+	if (!m_profilerProcess)
+	{
+		return;
+	}
+	m_profilerProcess->terminate();
+	m_profilerProcess->deleteLater();
+	m_profilerProcess = 0;
+	emit abortLaunch(tr("Profiler aborted"));
+}
+
+BaseProfiler *BaseProfilerFactory::createProfiler(InstancePtr instance, QObject *parent)
+{
+	return qobject_cast<BaseProfiler *>(createTool(instance, parent));
+}
diff --git a/libraries/logic/tools/BaseProfiler.h b/libraries/logic/tools/BaseProfiler.h
new file mode 100644
index 00000000..3340b7e4
--- /dev/null
+++ b/libraries/logic/tools/BaseProfiler.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include "BaseExternalTool.h"
+
+#include "multimc_logic_export.h"
+
+class BaseInstance;
+class SettingsObject;
+class LaunchTask;
+class QProcess;
+
+class MULTIMC_LOGIC_EXPORT BaseProfiler : public BaseExternalTool
+{
+	Q_OBJECT
+public:
+	explicit BaseProfiler(SettingsObjectPtr settings, InstancePtr instance, QObject *parent = 0);
+
+public
+slots:
+	void beginProfiling(std::shared_ptr<LaunchTask> process);
+	void abortProfiling();
+
+protected:
+	QProcess *m_profilerProcess;
+
+	virtual void beginProfilingImpl(std::shared_ptr<LaunchTask> process) = 0;
+	virtual void abortProfilingImpl();
+
+signals:
+	void readyToLaunch(const QString &message);
+	void abortLaunch(const QString &message);
+};
+
+class MULTIMC_LOGIC_EXPORT BaseProfilerFactory : public BaseExternalToolFactory
+{
+public:
+	virtual BaseProfiler *createProfiler(InstancePtr instance, QObject *parent = 0);
+};
diff --git a/libraries/logic/tools/JProfiler.cpp b/libraries/logic/tools/JProfiler.cpp
new file mode 100644
index 00000000..a0e3c895
--- /dev/null
+++ b/libraries/logic/tools/JProfiler.cpp
@@ -0,0 +1,116 @@
+#include "JProfiler.h"
+
+#include <QDir>
+
+#include "settings/SettingsObject.h"
+#include "launch/LaunchTask.h"
+#include "BaseInstance.h"
+
+class JProfiler : public BaseProfiler
+{
+	Q_OBJECT
+public:
+	JProfiler(SettingsObjectPtr settings, InstancePtr instance, QObject *parent = 0);
+
+private slots:
+	void profilerStarted();
+	void profilerFinished(int exit, QProcess::ExitStatus status);
+
+protected:
+	void beginProfilingImpl(std::shared_ptr<LaunchTask> process);
+
+private:
+	int listeningPort = 0;
+};
+
+JProfiler::JProfiler(SettingsObjectPtr settings, InstancePtr instance,
+					 QObject *parent)
+	: BaseProfiler(settings, instance, parent)
+{
+}
+
+void JProfiler::profilerStarted()
+{
+	emit readyToLaunch(tr("Listening on port: %1").arg(listeningPort));
+}
+
+void JProfiler::profilerFinished(int exit, QProcess::ExitStatus status)
+{
+	if (status == QProcess::CrashExit)
+	{
+		emit abortLaunch(tr("Profiler aborted"));
+	}
+	if (m_profilerProcess)
+	{
+		m_profilerProcess->deleteLater();
+		m_profilerProcess = 0;
+	}
+}
+
+void JProfiler::beginProfilingImpl(std::shared_ptr<LaunchTask> process)
+{
+	listeningPort = globalSettings->get("JProfilerPort").toInt();
+	QProcess *profiler = new QProcess(this);
+	QStringList profilerArgs =
+	{
+		"-d", QString::number(process->pid()),
+		"--gui",
+		"-p", QString::number(listeningPort)
+	};
+	auto basePath = globalSettings->get("JProfilerPath").toString();
+
+#ifdef Q_OS_WIN
+	QString profilerProgram = QDir(basePath).absoluteFilePath("bin/jpenable.exe");
+#else
+	QString profilerProgram = QDir(basePath).absoluteFilePath("bin/jpenable");
+#endif
+
+	profiler->setArguments(profilerArgs);
+	profiler->setProgram(profilerProgram);
+
+	connect(profiler, SIGNAL(started()), SLOT(profilerStarted()));
+	connect(profiler, SIGNAL(finished(int, QProcess::ExitStatus)), SLOT(profilerFinished(int,QProcess::ExitStatus)));
+
+	m_profilerProcess = profiler;
+	profiler->start();
+}
+
+void JProfilerFactory::registerSettings(SettingsObjectPtr settings)
+{
+	settings->registerSetting("JProfilerPath");
+	settings->registerSetting("JProfilerPort", 42042);
+	globalSettings = settings;
+}
+
+BaseExternalTool *JProfilerFactory::createTool(InstancePtr instance, QObject *parent)
+{
+	return new JProfiler(globalSettings, instance, parent);
+}
+
+bool JProfilerFactory::check(QString *error)
+{
+	return check(globalSettings->get("JProfilerPath").toString(), error);
+}
+
+bool JProfilerFactory::check(const QString &path, QString *error)
+{
+	if (path.isEmpty())
+	{
+		*error = QObject::tr("Empty path");
+		return false;
+	}
+	QDir dir(path);
+	if (!dir.exists())
+	{
+		*error = QObject::tr("Path does not exist");
+		return false;
+	}
+	if (!dir.exists("bin") || !(dir.exists("bin/jprofiler") || dir.exists("bin/jprofiler.exe")) || !dir.exists("bin/agent.jar"))
+	{
+		*error = QObject::tr("Invalid JProfiler install");
+		return false;
+	}
+	return true;
+}
+
+#include "JProfiler.moc"
diff --git a/libraries/logic/tools/JProfiler.h b/libraries/logic/tools/JProfiler.h
new file mode 100644
index 00000000..d658d6c2
--- /dev/null
+++ b/libraries/logic/tools/JProfiler.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "BaseProfiler.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT JProfilerFactory : public BaseProfilerFactory
+{
+public:
+	QString name() const override { return "JProfiler"; }
+	void registerSettings(SettingsObjectPtr settings) override;
+	BaseExternalTool *createTool(InstancePtr instance, QObject *parent = 0) override;
+	bool check(QString *error) override;
+	bool check(const QString &path, QString *error) override;
+};
diff --git a/libraries/logic/tools/JVisualVM.cpp b/libraries/logic/tools/JVisualVM.cpp
new file mode 100644
index 00000000..169967d9
--- /dev/null
+++ b/libraries/logic/tools/JVisualVM.cpp
@@ -0,0 +1,103 @@
+#include "JVisualVM.h"
+
+#include <QDir>
+#include <QStandardPaths>
+
+#include "settings/SettingsObject.h"
+#include "launch/LaunchTask.h"
+#include "BaseInstance.h"
+
+class JVisualVM : public BaseProfiler
+{
+	Q_OBJECT
+public:
+	JVisualVM(SettingsObjectPtr settings, InstancePtr instance, QObject *parent = 0);
+
+private slots:
+	void profilerStarted();
+	void profilerFinished(int exit, QProcess::ExitStatus status);
+
+protected:
+	void beginProfilingImpl(std::shared_ptr<LaunchTask> process);
+};
+
+
+JVisualVM::JVisualVM(SettingsObjectPtr settings, InstancePtr instance, QObject *parent)
+	: BaseProfiler(settings, instance, parent)
+{
+}
+
+void JVisualVM::profilerStarted()
+{
+	emit readyToLaunch(tr("JVisualVM started"));
+}
+
+void JVisualVM::profilerFinished(int exit, QProcess::ExitStatus status)
+{
+	if (status == QProcess::CrashExit)
+	{
+		emit abortLaunch(tr("Profiler aborted"));
+	}
+	if (m_profilerProcess)
+	{
+		m_profilerProcess->deleteLater();
+		m_profilerProcess = 0;
+	}
+}
+
+void JVisualVM::beginProfilingImpl(std::shared_ptr<LaunchTask> process)
+{
+	QProcess *profiler = new QProcess(this);
+	QStringList profilerArgs =
+	{
+		"--openpid", QString::number(process->pid())
+	};
+	auto programPath = globalSettings->get("JVisualVMPath").toString();
+
+	profiler->setArguments(profilerArgs);
+	profiler->setProgram(programPath);
+
+	connect(profiler, SIGNAL(started()), SLOT(profilerStarted()));
+	connect(profiler, SIGNAL(finished(int, QProcess::ExitStatus)), SLOT(profilerFinished(int,QProcess::ExitStatus)));
+
+	profiler->start();
+	m_profilerProcess = profiler;
+}
+
+void JVisualVMFactory::registerSettings(SettingsObjectPtr settings)
+{
+	QString defaultValue = QStandardPaths::findExecutable("jvisualvm");
+	if (defaultValue.isNull())
+	{
+		defaultValue = QStandardPaths::findExecutable("visualvm");
+	}
+	settings->registerSetting("JVisualVMPath", defaultValue);
+	globalSettings = settings;
+}
+
+BaseExternalTool *JVisualVMFactory::createTool(InstancePtr instance, QObject *parent)
+{
+	return new JVisualVM(globalSettings, instance, parent);
+}
+
+bool JVisualVMFactory::check(QString *error)
+{
+	return check(globalSettings->get("JVisualVMPath").toString(), error);
+}
+
+bool JVisualVMFactory::check(const QString &path, QString *error)
+{
+	if (path.isEmpty())
+	{
+		*error = QObject::tr("Empty path");
+		return false;
+	}
+	if (!QDir::isAbsolutePath(path) || !QFileInfo(path).isExecutable() || !path.contains("visualvm"))
+	{
+		*error = QObject::tr("Invalid path to JVisualVM");
+		return false;
+	}
+	return true;
+}
+
+#include "JVisualVM.moc"
diff --git a/libraries/logic/tools/JVisualVM.h b/libraries/logic/tools/JVisualVM.h
new file mode 100644
index 00000000..0674da13
--- /dev/null
+++ b/libraries/logic/tools/JVisualVM.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "BaseProfiler.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT JVisualVMFactory : public BaseProfilerFactory
+{
+public:
+	QString name() const override { return "JVisualVM"; }
+	void registerSettings(SettingsObjectPtr settings) override;
+	BaseExternalTool *createTool(InstancePtr instance, QObject *parent = 0) override;
+	bool check(QString *error) override;
+	bool check(const QString &path, QString *error) override;
+};
diff --git a/libraries/logic/tools/MCEditTool.cpp b/libraries/logic/tools/MCEditTool.cpp
new file mode 100644
index 00000000..32695c8d
--- /dev/null
+++ b/libraries/logic/tools/MCEditTool.cpp
@@ -0,0 +1,124 @@
+#include "MCEditTool.h"
+
+#include <QDir>
+#include <QProcess>
+#include <QUrl>
+
+#include "settings/SettingsObject.h"
+#include "BaseInstance.h"
+#include "minecraft/MinecraftInstance.h"
+
+MCEditTool::MCEditTool(SettingsObjectPtr settings, InstancePtr instance, QObject *parent)
+	: BaseDetachedTool(settings, instance, parent)
+{
+}
+
+QString MCEditTool::getSave() const
+{
+	// FIXME: mixing logic and UI!!!!
+	auto mcInstance = std::dynamic_pointer_cast<MinecraftInstance>(m_instance);
+	if(!mcInstance)
+	{
+		return QString();
+	}
+	QDir saves(mcInstance->minecraftRoot() + "/saves");
+	QStringList worlds = saves.entryList(QDir::Dirs | QDir::NoDotAndDotDot);
+	QMutableListIterator<QString> it(worlds);
+	while (it.hasNext())
+	{
+		it.next();
+		if (!QDir(saves.absoluteFilePath(it.value())).exists("level.dat"))
+		{
+			it.remove();
+		}
+	}
+	bool ok = true;
+	/*
+	const QString save = QInputDialog::getItem(QApplication::activeWindow(), tr("MCEdit"), tr("Choose which world to open:"),
+		worlds, 0, false, &ok);
+	if (ok)
+	{
+		return saves.absoluteFilePath(save);
+	}
+	*/
+	return QString();
+}
+
+void MCEditTool::runImpl()
+{
+	const QString mceditPath = globalSettings->get("MCEditPath").toString();
+	const QString save = getSave();
+	if (save.isNull())
+	{
+		return;
+	}
+#ifdef Q_OS_OSX
+	QProcess *process = new QProcess();
+	connect(process, SIGNAL(finished(int, QProcess::ExitStatus)), process, SLOT(deleteLater()));
+	process->setProgram(mceditPath);
+	process->setArguments(QStringList() << save);
+	process->start();
+#else
+	QDir mceditDir(mceditPath);
+	QString program;
+	#ifdef Q_OS_LINUX
+	if (mceditDir.exists("mcedit.py"))
+	{
+		program = mceditDir.absoluteFilePath("mcedit.py");
+	}
+	else if (mceditDir.exists("mcedit.sh"))
+	{
+		program = mceditDir.absoluteFilePath("mcedit.sh");
+	}
+	#elif defined(Q_OS_WIN32)
+	if (mceditDir.exists("mcedit.exe"))
+	{
+		program = mceditDir.absoluteFilePath("mcedit.exe");
+	}
+	else if (mceditDir.exists("mcedit2.exe"))
+	{
+		program = mceditDir.absoluteFilePath("mcedit2.exe");
+	}
+	#endif
+	/*
+	if(program.size())
+	{
+		DesktopServices::openFile(program, save, mceditPath);
+	}
+	*/
+#endif
+}
+
+void MCEditFactory::registerSettings(SettingsObjectPtr settings)
+{
+	settings->registerSetting("MCEditPath");
+	globalSettings = settings;
+}
+BaseExternalTool *MCEditFactory::createTool(InstancePtr instance, QObject *parent)
+{
+	return new MCEditTool(globalSettings, instance, parent);
+}
+bool MCEditFactory::check(QString *error)
+{
+	return check(globalSettings->get("MCEditPath").toString(), error);
+}
+bool MCEditFactory::check(const QString &path, QString *error)
+{
+	if (path.isEmpty())
+	{
+		*error = QObject::tr("Path is empty");
+		return false;
+	}
+	const QDir dir(path);
+	if (!dir.exists())
+	{
+		*error = QObject::tr("Path does not exist");
+		return false;
+	}
+	if (!dir.exists("mcedit.sh") && !dir.exists("mcedit.py") && !dir.exists("mcedit.exe") && !dir.exists("Contents") && !dir.exists("mcedit2.exe"))
+	{
+		*error = QObject::tr("Path does not seem to be a MCEdit path");
+		return false;
+	}
+	return true;
+}
diff --git a/libraries/logic/tools/MCEditTool.h b/libraries/logic/tools/MCEditTool.h
new file mode 100644
index 00000000..c287f1ea
--- /dev/null
+++ b/libraries/logic/tools/MCEditTool.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include "BaseExternalTool.h"
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT MCEditTool : public BaseDetachedTool
+{
+	Q_OBJECT
+public:
+	explicit MCEditTool(SettingsObjectPtr settings, InstancePtr instance, QObject *parent = 0);
+
+protected:
+	QString getSave() const;
+	void runImpl() override;
+};
+
+class MULTIMC_LOGIC_EXPORT MCEditFactory : public BaseDetachedToolFactory
+{
+public:
+	QString name() const override { return "MCEdit"; }
+	void registerSettings(SettingsObjectPtr settings) override;
+	BaseExternalTool *createTool(InstancePtr instance, QObject *parent = 0) override;
+	bool check(QString *error) override;
+	bool check(const QString &path, QString *error) override;
+};
diff --git a/libraries/logic/trans/TranslationDownloader.cpp b/libraries/logic/trans/TranslationDownloader.cpp
new file mode 100644
index 00000000..ee5c1fd2
--- /dev/null
+++ b/libraries/logic/trans/TranslationDownloader.cpp
@@ -0,0 +1,53 @@
+#include "TranslationDownloader.h"
+#include "net/NetJob.h"
+#include "net/CacheDownload.h"
+#include "net/URLConstants.h"
+#include "Env.h"
+#include <QDebug>
+
+TranslationDownloader::TranslationDownloader()
+{
+}
+void TranslationDownloader::downloadTranslations()
+{
+	qDebug() << "Downloading Translations Index...";
+	m_index_job.reset(new NetJob("Translations Index"));
+	m_index_task = ByteArrayDownload::make(QUrl("http://files.multimc.org/translations/index"));
+	m_index_job->addNetAction(m_index_task);
+	connect(m_index_job.get(), &NetJob::failed, this, &TranslationDownloader::indexFailed);
+	connect(m_index_job.get(), &NetJob::succeeded, this, &TranslationDownloader::indexRecieved);
+	m_index_job->start();
+}
+void TranslationDownloader::indexRecieved()
+{
+	qDebug() << "Got translations index!";
+	m_dl_job.reset(new NetJob("Translations"));
+	QList<QByteArray> lines = m_index_task->m_data.split('\n');
+	for (const auto line : lines)
+	{
+		if (!line.isEmpty())
+		{
+			MetaEntryPtr entry = ENV.metacache()->resolveEntry("translations", "mmc_" + line);
+			entry->setStale(true);
+			CacheDownloadPtr dl = CacheDownload::make(
+				QUrl(URLConstants::TRANSLATIONS_BASE_URL + line),
+				entry);
+			m_dl_job->addNetAction(dl);
+		}
+	}
+	connect(m_dl_job.get(), &NetJob::succeeded, this, &TranslationDownloader::dlGood);
+	connect(m_dl_job.get(), &NetJob::failed, this, &TranslationDownloader::dlFailed);
+	m_dl_job->start();
+}
+void TranslationDownloader::dlFailed(QString reason)
+{
+	qCritical() << "Translations Download Failed:" << reason;
+}
+void TranslationDownloader::dlGood()
+{
+	qDebug() << "Got translations!";
+}
+void TranslationDownloader::indexFailed(QString reason)
+{
+	qCritical() << "Translations Index Download Failed:" << reason;
+}
diff --git a/libraries/logic/trans/TranslationDownloader.h b/libraries/logic/trans/TranslationDownloader.h
new file mode 100644
index 00000000..e7893805
--- /dev/null
+++ b/libraries/logic/trans/TranslationDownloader.h
@@ -0,0 +1,32 @@
+#pragma once
+
+#include <QList>
+#include <QUrl>
+#include <memory>
+#include <QObject>
+#include <net/NetJob.h>
+#include "multimc_logic_export.h"
+
+class ByteArrayDownload;
+class NetJob;
+
+class MULTIMC_LOGIC_EXPORT TranslationDownloader : public QObject
+{
+	Q_OBJECT
+
+public:
+	TranslationDownloader();
+
+	void downloadTranslations();
+
+private slots:
+	void indexRecieved();
+	void indexFailed(QString reason);
+	void dlFailed(QString reason);
+	void dlGood();
+
+private:
+	std::shared_ptr<ByteArrayDownload> m_index_task;
+	NetJobPtr m_dl_job;
+	NetJobPtr m_index_job;
+};
diff --git a/libraries/logic/updater/DownloadTask.cpp b/libraries/logic/updater/DownloadTask.cpp
new file mode 100644
index 00000000..6947e8bf
--- /dev/null
+++ b/libraries/logic/updater/DownloadTask.cpp
@@ -0,0 +1,169 @@
+/* Copyright 2013-2014 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "DownloadTask.h"
+
+#include "updater/UpdateChecker.h"
+#include "GoUpdate.h"
+#include "net/NetJob.h"
+
+#include <QFile>
+#include <QTemporaryDir>
+#include <QCryptographicHash>
+
+namespace GoUpdate
+{
+
+DownloadTask::DownloadTask(Status status, QString target, QObject *parent)
+	: Task(parent), m_updateFilesDir(target)
+{
+	m_status = status;
+
+	m_updateFilesDir.setAutoRemove(false);
+}
+
+void DownloadTask::executeTask()
+{
+	loadVersionInfo();
+}
+
+void DownloadTask::loadVersionInfo()
+{
+	setStatus(tr("Loading version information..."));
+
+	m_currentVersionFileListDownload.reset();
+	m_newVersionFileListDownload.reset();
+
+	NetJob *netJob = new NetJob("Version Info");
+
+	// Find the index URL.
+	QUrl newIndexUrl = QUrl(m_status.newRepoUrl).resolved(QString::number(m_status.newVersionId) + ".json");
+	qDebug() << m_status.newRepoUrl << " turns into " << newIndexUrl;
+
+	netJob->addNetAction(m_newVersionFileListDownload = ByteArrayDownload::make(newIndexUrl));
+
+	// If we have a current version URL, get that one too.
+	if (!m_status.currentRepoUrl.isEmpty())
+	{
+		QUrl cIndexUrl = QUrl(m_status.currentRepoUrl).resolved(QString::number(m_status.currentVersionId) + ".json");
+		netJob->addNetAction(m_currentVersionFileListDownload = ByteArrayDownload::make(cIndexUrl));
+		qDebug() << m_status.currentRepoUrl << " turns into " << cIndexUrl;
+	}
+
+	// connect signals and start the job
+	connect(netJob, &NetJob::succeeded, this, &DownloadTask::processDownloadedVersionInfo);
+	connect(netJob, &NetJob::failed, this, &DownloadTask::vinfoDownloadFailed);
+	m_vinfoNetJob.reset(netJob);
+	netJob->start();
+}
+
+void DownloadTask::vinfoDownloadFailed()
+{
+	// Something failed. We really need the second download (current version info), so parse
+	// downloads anyways as long as the first one succeeded.
+	if (m_newVersionFileListDownload->m_status != Job_Failed)
+	{
+		processDownloadedVersionInfo();
+		return;
+	}
+
+	// TODO: Give a more detailed error message.
+	qCritical() << "Failed to download version info files.";
+	emitFailed(tr("Failed to download version info files."));
+}
+
+void DownloadTask::processDownloadedVersionInfo()
+{
+	VersionFileList m_currentVersionFileList;
+	VersionFileList m_newVersionFileList;
+
+	setStatus(tr("Reading file list for new version..."));
+	qDebug() << "Reading file list for new version...";
+	QString error;
+	if (!parseVersionInfo(m_newVersionFileListDownload->m_data, m_newVersionFileList, error))
+	{
+		qCritical() << error;
+		emitFailed(error);
+		return;
+	}
+
+	// if we have the current version info, use it.
+	if (m_currentVersionFileListDownload && m_currentVersionFileListDownload->m_status != Job_Failed)
+	{
+		setStatus(tr("Reading file list for current version..."));
+		qDebug() << "Reading file list for current version...";
+		// if this fails, it's not a complete loss.
+		QString error;
+		if(!parseVersionInfo( m_currentVersionFileListDownload->m_data, m_currentVersionFileList, error))
+		{
+			qDebug() << error << "This is not a fatal error.";
+		}
+	}
+
+	// We don't need this any more.
+	m_currentVersionFileListDownload.reset();
+	m_newVersionFileListDownload.reset();
+	m_vinfoNetJob.reset();
+
+	setStatus(tr("Processing file lists - figuring out how to install the update..."));
+
+	// make a new netjob for the actual update files
+	NetJobPtr netJob (new NetJob("Update Files"));
+
+	// fill netJob and operationList
+	if (!processFileLists(m_currentVersionFileList, m_newVersionFileList, m_status.rootPath, m_updateFilesDir.path(), netJob, m_operations))
+	{
+		emitFailed(tr("Failed to process update lists..."));
+		return;
+	}
+
+	// Now start the download.
+	QObject::connect(netJob.get(), &NetJob::succeeded, this, &DownloadTask::fileDownloadFinished);
+	QObject::connect(netJob.get(), &NetJob::progress, this, &DownloadTask::fileDownloadProgressChanged);
+	QObject::connect(netJob.get(), &NetJob::failed, this, &DownloadTask::fileDownloadFailed);
+
+	setStatus(tr("Downloading %1 update files.").arg(QString::number(netJob->size())));
+	qDebug() << "Begin downloading update files to" << m_updateFilesDir.path();
+	m_filesNetJob = netJob;
+	m_filesNetJob->start();
+}
+
+void DownloadTask::fileDownloadFinished()
+{
+	emitSucceeded();
+}
+
+void DownloadTask::fileDownloadFailed(QString reason)
+{
+	qCritical() << "Failed to download update files:" << reason;
+	emitFailed(tr("Failed to download update files: %1").arg(reason));
+}
+
+void DownloadTask::fileDownloadProgressChanged(qint64 current, qint64 total)
+{
+	setProgress(current, total);
+}
+
+QString DownloadTask::updateFilesDir()
+{
+	return m_updateFilesDir.path();
+}
+
+OperationList DownloadTask::operations()
+{
+	return m_operations;
+}
+
+}
\ No newline at end of file
diff --git a/libraries/logic/updater/DownloadTask.h b/libraries/logic/updater/DownloadTask.h
new file mode 100644
index 00000000..83b4a142
--- /dev/null
+++ b/libraries/logic/updater/DownloadTask.h
@@ -0,0 +1,95 @@
+/* Copyright 2013-2014 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "tasks/Task.h"
+#include "net/NetJob.h"
+#include "GoUpdate.h"
+
+#include "multimc_logic_export.h"
+
+namespace GoUpdate
+{
+/*!
+ * The DownloadTask is a task that takes a given version ID and repository URL,
+ * downloads that version's files from the repository, and prepares to install them.
+ */
+class MULTIMC_LOGIC_EXPORT DownloadTask : public Task
+{
+	Q_OBJECT
+
+public:
+	/**
+	 * Create a download task
+	 *
+	 * target is a template - XXXXXX at the end will be replaced with a random generated string, ensuring uniqueness
+	 */
+	explicit DownloadTask(Status status, QString target, QObject* parent = 0);
+
+	/// Get the directory that will contain the update files.
+	QString updateFilesDir();
+
+	/// Get the list of operations that should be done
+	OperationList operations();
+
+	/// set updater download behavior
+	void setUseLocalUpdater(bool useLocal);
+
+protected:
+	//! Entry point for tasks.
+	virtual void executeTask() override;
+
+	/*!
+	 * Downloads the version info files from the repository.
+	 * The files for both the current build, and the build that we're updating to need to be downloaded.
+	 * If the current version's info file can't be found, MultiMC will not delete files that
+	 * were removed between versions. It will still replace files that have changed, however.
+	 * Note that although the repository URL for the current version is not given to the update task,
+	 * the task will attempt to look it up in the UpdateChecker's channel list.
+	 * If an error occurs here, the function will call emitFailed and return false.
+	 */
+	void loadVersionInfo();
+
+	NetJobPtr m_vinfoNetJob;
+	ByteArrayDownloadPtr m_currentVersionFileListDownload;
+	ByteArrayDownloadPtr m_newVersionFileListDownload;
+
+	NetJobPtr m_filesNetJob;
+
+	Status m_status;
+
+	OperationList m_operations;
+
+	/*!
+	 * Temporary directory to store update files in.
+	 * This will be set to not auto delete. Task will fail if this fails to be created.
+	 */
+	QTemporaryDir m_updateFilesDir;
+
+protected slots:
+	/*!
+	 * This function is called when version information is finished downloading
+	 * and at least the new file list download succeeded
+	 */
+	void processDownloadedVersionInfo();
+	void vinfoDownloadFailed();
+
+	void fileDownloadFinished();
+	void fileDownloadFailed(QString reason);
+	void fileDownloadProgressChanged(qint64 current, qint64 total);
+};
+
+}
\ No newline at end of file
diff --git a/libraries/logic/updater/GoUpdate.cpp b/libraries/logic/updater/GoUpdate.cpp
new file mode 100644
index 00000000..60d50e04
--- /dev/null
+++ b/libraries/logic/updater/GoUpdate.cpp
@@ -0,0 +1,216 @@
+#include "GoUpdate.h"
+#include <QDebug>
+#include <QDomDocument>
+#include <QFile>
+#include <Env.h>
+#include <FileSystem.h>
+
+namespace GoUpdate
+{
+
+bool parseVersionInfo(const QByteArray &data, VersionFileList &list, QString &error)
+{
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		error = QString("Failed to parse version info JSON: %1 at %2")
+					.arg(jsonError.errorString())
+					.arg(jsonError.offset);
+		qCritical() << error;
+		return false;
+	}
+
+	QJsonObject json = jsonDoc.object();
+
+	qDebug() << data;
+	qDebug() << "Loading version info from JSON.";
+	QJsonArray filesArray = json.value("Files").toArray();
+	for (QJsonValue fileValue : filesArray)
+	{
+		QJsonObject fileObj = fileValue.toObject();
+
+		QString file_path = fileObj.value("Path").toString();
+#ifdef Q_OS_MAC
+		// On OSX, the paths for the updater need to be fixed.
+		// basically, anything that isn't in the .app folder is ignored.
+		// everything else is changed so the code that processes the files actually finds
+		// them and puts the replacements in the right spots.
+		fixPathForOSX(file_path);
+#endif
+		VersionFileEntry file{file_path,		fileObj.value("Perms").toVariant().toInt(),
+							  FileSourceList(), fileObj.value("MD5").toString(), };
+		qDebug() << "File" << file.path << "with perms" << file.mode;
+
+		QJsonArray sourceArray = fileObj.value("Sources").toArray();
+		for (QJsonValue val : sourceArray)
+		{
+			QJsonObject sourceObj = val.toObject();
+
+			QString type = sourceObj.value("SourceType").toString();
+			if (type == "http")
+			{
+				file.sources.append(FileSource("http", sourceObj.value("Url").toString()));
+			}
+			else
+			{
+				qWarning() << "Unknown source type" << type << "ignored.";
+			}
+		}
+
+		qDebug() << "Loaded info for" << file.path;
+
+		list.append(file);
+	}
+
+	return true;
+}
+
+bool processFileLists
+(
+	const VersionFileList &currentVersion,
+	const VersionFileList &newVersion,
+	const QString &rootPath,
+	const QString &tempPath,
+	NetJobPtr job,
+	OperationList &ops
+)
+{
+	// First, if we've loaded the current version's file list, we need to iterate through it and
+	// delete anything in the current one version's list that isn't in the new version's list.
+	for (VersionFileEntry entry : currentVersion)
+	{
+		QFileInfo toDelete(FS::PathCombine(rootPath, entry.path));
+		if (!toDelete.exists())
+		{
+			qCritical() << "Expected file " << toDelete.absoluteFilePath()
+						 << " doesn't exist!";
+		}
+		bool keep = false;
+
+		//
+		for (VersionFileEntry newEntry : newVersion)
+		{
+			if (newEntry.path == entry.path)
+			{
+				qDebug() << "Not deleting" << entry.path
+							 << "because it is still present in the new version.";
+				keep = true;
+				break;
+			}
+		}
+
+		// If the loop reaches the end and we didn't find a match, delete the file.
+		if (!keep)
+		{
+			if (toDelete.exists())
+				ops.append(Operation::DeleteOp(entry.path));
+		}
+	}
+
+	// Next, check each file in MultiMC's folder and see if we need to update them.
+	for (VersionFileEntry entry : newVersion)
+	{
+		// TODO: Let's not MD5sum a ton of files on the GUI thread. We should probably find a
+		// way to do this in the background.
+		QString fileMD5;
+		QString realEntryPath = FS::PathCombine(rootPath, entry.path);
+		QFile entryFile(realEntryPath);
+		QFileInfo entryInfo(realEntryPath);
+
+		bool needs_upgrade = false;
+		if (!entryFile.exists())
+		{
+			needs_upgrade = true;
+		}
+		else
+		{
+			bool pass = true;
+			if (!entryInfo.isReadable())
+			{
+				qCritical() << "File " << realEntryPath << " is not readable.";
+				pass = false;
+			}
+			if (!entryInfo.isWritable())
+			{
+				qCritical() << "File " << realEntryPath << " is not writable.";
+				pass = false;
+			}
+			if (!entryFile.open(QFile::ReadOnly))
+			{
+				qCritical() << "File " << realEntryPath << " cannot be opened for reading.";
+				pass = false;
+			}
+			if (!pass)
+			{
+				ops.clear();
+				return false;
+			}
+		}
+
+		if(!needs_upgrade)
+		{
+			QCryptographicHash hash(QCryptographicHash::Md5);
+			auto foo = entryFile.readAll();
+
+			hash.addData(foo);
+			fileMD5 = hash.result().toHex();
+			if ((fileMD5 != entry.md5))
+			{
+				qDebug() << "MD5Sum does not match!";
+				qDebug() << "Expected:'" << entry.md5 << "'";
+				qDebug() << "Got:     '" << fileMD5 << "'";
+				needs_upgrade = true;
+			}
+		}
+
+		// skip file. it doesn't need an upgrade.
+		if (!needs_upgrade)
+		{
+			qDebug() << "File" << realEntryPath << " does not need updating.";
+			continue;
+		}
+
+		// yep. this file actually needs an upgrade. PROCEED.
+		qDebug() << "Found file" << realEntryPath << " that needs updating.";
+
+		// Go through the sources list and find one to use.
+		// TODO: Make a NetAction that takes a source list and tries each of them until one
+		// works. For now, we'll just use the first http one.
+		for (FileSource source : entry.sources)
+		{
+			if (source.type != "http")
+				continue;
+
+			qDebug() << "Will download" << entry.path << "from" << source.url;
+
+			// Download it to updatedir/<filepath>-<md5> where filepath is the file's
+			// path with slashes replaced by underscores.
+			QString dlPath = FS::PathCombine(tempPath, QString(entry.path).replace("/", "_"));
+
+			// We need to download the file to the updatefiles folder and add a task
+			// to copy it to its install path.
+			auto download = MD5EtagDownload::make(source.url, dlPath);
+			download->m_expected_md5 = entry.md5;
+			job->addNetAction(download);
+			ops.append(Operation::CopyOp(dlPath, entry.path, entry.mode));
+		}
+	}
+	return true;
+}
+
+bool fixPathForOSX(QString &path)
+{
+	if (path.startsWith("MultiMC.app/"))
+	{
+		// remove the prefix and add a new, more appropriate one.
+		path.remove(0, 12);
+		return true;
+	}
+	else
+	{
+		qCritical() << "Update path not within .app: " << path;
+		return false;
+	}
+}
+}
\ No newline at end of file
diff --git a/libraries/logic/updater/GoUpdate.h b/libraries/logic/updater/GoUpdate.h
new file mode 100644
index 00000000..b8a534de
--- /dev/null
+++ b/libraries/logic/updater/GoUpdate.h
@@ -0,0 +1,133 @@
+#pragma once
+#include <QByteArray>
+#include <net/NetJob.h>
+
+#include "multimc_logic_export.h"
+
+namespace GoUpdate
+{
+
+/**
+ * A temporary object exchanged between updated checker and the actual update task
+ */
+struct MULTIMC_LOGIC_EXPORT Status
+{
+	bool updateAvailable = false;
+
+	int newVersionId = -1;
+	QString newRepoUrl;
+
+	int currentVersionId = -1;
+	QString currentRepoUrl;
+
+	// path to the root of the application
+	QString rootPath;
+};
+
+/**
+ * Struct that describes an entry in a VersionFileEntry's `Sources` list.
+ */
+struct MULTIMC_LOGIC_EXPORT FileSource
+{
+	FileSource(QString type, QString url, QString compression="")
+	{
+		this->type = type;
+		this->url = url;
+		this->compressionType = compression;
+	}
+
+	bool operator==(const FileSource &f2) const
+	{
+		return type == f2.type && url == f2.url && compressionType == f2.compressionType;
+	}
+
+	QString type;
+	QString url;
+	QString compressionType;
+};
+typedef QList<FileSource> FileSourceList;
+
+/**
+ * Structure that describes an entry in a GoUpdate version's `Files` list.
+ */
+struct MULTIMC_LOGIC_EXPORT VersionFileEntry
+{
+	QString path;
+	int mode;
+	FileSourceList sources;
+	QString md5;
+	bool operator==(const VersionFileEntry &v2) const
+	{
+		return path == v2.path && mode == v2.mode && sources == v2.sources && md5 == v2.md5;
+	}
+};
+typedef QList<VersionFileEntry> VersionFileList;
+
+/**
+ * Structure that describes an operation to perform when installing updates.
+ */
+struct MULTIMC_LOGIC_EXPORT Operation
+{
+	static Operation CopyOp(QString fsource, QString fdest, int fmode=0644)
+	{
+		return Operation{OP_REPLACE, fsource, fdest, fmode};
+	}
+	static Operation DeleteOp(QString file)
+	{
+		return Operation{OP_DELETE, file, "", 0644};
+	}
+
+	// FIXME: for some types, some of the other fields are irrelevant!
+	bool operator==(const Operation &u2) const
+	{
+		return type == u2.type && file == u2.file && dest == u2.dest && mode == u2.mode;
+	}
+
+	//! Specifies the type of operation that this is.
+	enum Type
+	{
+		OP_REPLACE,
+		OP_DELETE,
+	} type;
+
+	//! The file to operate on.
+	QString file;
+
+	//! The destination file.
+	QString dest;
+
+	//! The mode to change the source file to.
+	int mode;
+};
+typedef QList<Operation> OperationList;
+
+/**
+ * Loads the file list from the given version info JSON object into the given list.
+ */
+bool MULTIMC_LOGIC_EXPORT parseVersionInfo(const QByteArray &data, VersionFileList& list, QString &error);
+
+/*!
+ * Takes a list of file entries for the current version's files and the new version's files
+ * and populates the downloadList and operationList with information about how to download and install the update.
+ */
+bool MULTIMC_LOGIC_EXPORT processFileLists
+(
+	const VersionFileList &currentVersion,
+	const VersionFileList &newVersion,
+	const QString &rootPath,
+	const QString &tempPath,
+	NetJobPtr job,
+	OperationList &ops
+);
+
+/*!
+ * This fixes destination paths for OSX - removes 'MultiMC.app' prefix
+ * The updater runs in MultiMC.app/Contents/MacOs by default
+ * The destination paths are such as this: MultiMC.app/blah/blah
+ *
+ * @return false if the path couldn't be fixed (is invalid)
+ */
+bool MULTIMC_LOGIC_EXPORT fixPathForOSX(QString &path);
+
+}
+Q_DECLARE_METATYPE(GoUpdate::Status);
\ No newline at end of file
diff --git a/libraries/logic/updater/UpdateChecker.cpp b/libraries/logic/updater/UpdateChecker.cpp
new file mode 100644
index 00000000..1cdac916
--- /dev/null
+++ b/libraries/logic/updater/UpdateChecker.cpp
@@ -0,0 +1,269 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "UpdateChecker.h"
+
+#include <QJsonObject>
+#include <QJsonArray>
+#include <QJsonValue>
+#include <QDebug>
+
+#define API_VERSION 0
+#define CHANLIST_FORMAT 0
+
+UpdateChecker::UpdateChecker(QString channelListUrl, QString currentChannel, int currentBuild)
+{
+	m_channelListUrl = channelListUrl;
+	m_currentChannel = currentChannel;
+	m_currentBuild = currentBuild;
+
+	m_updateChecking = false;
+	m_chanListLoading = false;
+	m_checkUpdateWaiting = false;
+	m_chanListLoaded = false;
+}
+
+QList<UpdateChecker::ChannelListEntry> UpdateChecker::getChannelList() const
+{
+	return m_channels;
+}
+
+bool UpdateChecker::hasChannels() const
+{
+	return !m_channels.isEmpty();
+}
+
+void UpdateChecker::checkForUpdate(QString updateChannel, bool notifyNoUpdate)
+{
+	qDebug() << "Checking for updates.";
+
+	// If the channel list hasn't loaded yet, load it and defer checking for updates until
+	// later.
+	if (!m_chanListLoaded)
+	{
+		qDebug() << "Channel list isn't loaded yet. Loading channel list and deferring "
+						"update check.";
+		m_checkUpdateWaiting = true;
+		m_deferredUpdateChannel = updateChannel;
+		updateChanList(notifyNoUpdate);
+		return;
+	}
+
+	if (m_updateChecking)
+	{
+		qDebug() << "Ignoring update check request. Already checking for updates.";
+		return;
+	}
+
+	m_updateChecking = true;
+
+	// Find the desired channel within the channel list and get its repo URL. If if cannot be
+	// found, error.
+	m_newRepoUrl = "";
+	for (ChannelListEntry entry : m_channels)
+	{
+		if (entry.id == updateChannel)
+			m_newRepoUrl = entry.url;
+		if (entry.id == m_currentChannel)
+			m_currentRepoUrl = entry.url;
+	}
+
+	qDebug() << "m_repoUrl = " << m_newRepoUrl;
+
+	// If we didn't find our channel, error.
+	if (m_newRepoUrl.isEmpty())
+	{
+		qCritical() << "m_repoUrl is empty!";
+		emit updateCheckFailed();
+		return;
+	}
+
+	QUrl indexUrl = QUrl(m_newRepoUrl).resolved(QUrl("index.json"));
+
+	auto job = new NetJob("GoUpdate Repository Index");
+	job->addNetAction(ByteArrayDownload::make(indexUrl));
+	connect(job, &NetJob::succeeded, [this, notifyNoUpdate]()
+	{ updateCheckFinished(notifyNoUpdate); });
+	connect(job, &NetJob::failed, this, &UpdateChecker::updateCheckFailed);
+	indexJob.reset(job);
+	job->start();
+}
+
+void UpdateChecker::updateCheckFinished(bool notifyNoUpdate)
+{
+	qDebug() << "Finished downloading repo index. Checking for new versions.";
+
+	QJsonParseError jsonError;
+	QByteArray data;
+	{
+		ByteArrayDownloadPtr dl =
+			std::dynamic_pointer_cast<ByteArrayDownload>(indexJob->first());
+		data = dl->m_data;
+		indexJob.reset();
+	}
+
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+	if (jsonError.error != QJsonParseError::NoError || !jsonDoc.isObject())
+	{
+		qCritical() << "Failed to parse GoUpdate repository index. JSON error"
+					 << jsonError.errorString() << "at offset" << jsonError.offset;
+		return;
+	}
+
+	QJsonObject object = jsonDoc.object();
+
+	bool success = false;
+	int apiVersion = object.value("ApiVersion").toVariant().toInt(&success);
+	if (apiVersion != API_VERSION || !success)
+	{
+		qCritical() << "Failed to check for updates. API version mismatch. We're using"
+					 << API_VERSION << "server has" << apiVersion;
+		return;
+	}
+
+	qDebug() << "Processing repository version list.";
+	QJsonObject newestVersion;
+	QJsonArray versions = object.value("Versions").toArray();
+	for (QJsonValue versionVal : versions)
+	{
+		QJsonObject version = versionVal.toObject();
+		if (newestVersion.value("Id").toVariant().toInt() <
+			version.value("Id").toVariant().toInt())
+		{
+			newestVersion = version;
+		}
+	}
+
+	// We've got the version with the greatest ID number. Now compare it to our current build
+	// number and update if they're different.
+	int newBuildNumber = newestVersion.value("Id").toVariant().toInt();
+	if (newBuildNumber != m_currentBuild)
+	{
+		qDebug() << "Found newer version with ID" << newBuildNumber;
+		// Update!
+		GoUpdate::Status updateStatus;
+		updateStatus.updateAvailable = true;
+		updateStatus.currentVersionId = m_currentBuild;
+		updateStatus.currentRepoUrl = m_currentRepoUrl;
+		updateStatus.newVersionId = newBuildNumber;
+		updateStatus.newRepoUrl = m_newRepoUrl;
+		emit updateAvailable(updateStatus);
+	}
+	else if (notifyNoUpdate)
+	{
+		emit noUpdateFound();
+	}
+
+	m_updateChecking = false;
+}
+
+void UpdateChecker::updateCheckFailed()
+{
+	qCritical() << "Update check failed for reasons unknown.";
+}
+
+void UpdateChecker::updateChanList(bool notifyNoUpdate)
+{
+	qDebug() << "Loading the channel list.";
+
+	if (m_channelListUrl.isEmpty())
+	{
+		qCritical() << "Failed to update channel list. No channel list URL set."
+					<< "If you'd like to use MultiMC's update system, please pass the channel "
+						"list URL to CMake at compile time.";
+		return;
+	}
+
+	m_chanListLoading = true;
+	NetJob *job = new NetJob("Update System Channel List");
+	job->addNetAction(ByteArrayDownload::make(QUrl(m_channelListUrl)));
+	connect(job, &NetJob::succeeded, [this, notifyNoUpdate]()
+	{ chanListDownloadFinished(notifyNoUpdate); });
+	QObject::connect(job, &NetJob::failed, this, &UpdateChecker::chanListDownloadFailed);
+	chanListJob.reset(job);
+	job->start();
+}
+
+void UpdateChecker::chanListDownloadFinished(bool notifyNoUpdate)
+{
+	QByteArray data;
+	{
+		ByteArrayDownloadPtr dl =
+			std::dynamic_pointer_cast<ByteArrayDownload>(chanListJob->first());
+		data = dl->m_data;
+		chanListJob.reset();
+	}
+
+	QJsonParseError jsonError;
+	QJsonDocument jsonDoc = QJsonDocument::fromJson(data, &jsonError);
+	if (jsonError.error != QJsonParseError::NoError)
+	{
+		// TODO: Report errors to the user.
+		qCritical() << "Failed to parse channel list JSON:" << jsonError.errorString() << "at"
+					 << jsonError.offset;
+		return;
+	}
+
+	QJsonObject object = jsonDoc.object();
+
+	bool success = false;
+	int formatVersion = object.value("format_version").toVariant().toInt(&success);
+	if (formatVersion != CHANLIST_FORMAT || !success)
+	{
+		qCritical()
+			<< "Failed to check for updates. Channel list format version mismatch. We're using"
+			<< CHANLIST_FORMAT << "server has" << formatVersion;
+		return;
+	}
+
+	// Load channels into a temporary array.
+	QList<ChannelListEntry> loadedChannels;
+	QJsonArray channelArray = object.value("channels").toArray();
+	for (QJsonValue chanVal : channelArray)
+	{
+		QJsonObject channelObj = chanVal.toObject();
+		ChannelListEntry entry{channelObj.value("id").toVariant().toString(),
+							   channelObj.value("name").toVariant().toString(),
+							   channelObj.value("description").toVariant().toString(),
+							   channelObj.value("url").toVariant().toString()};
+		if (entry.id.isEmpty() || entry.name.isEmpty() || entry.url.isEmpty())
+		{
+			qCritical() << "Channel list entry with empty ID, name, or URL. Skipping.";
+			continue;
+		}
+		loadedChannels.append(entry);
+	}
+
+	// Swap  the channel list we just loaded into the object's channel list.
+	m_channels.swap(loadedChannels);
+
+	m_chanListLoading = false;
+	m_chanListLoaded = true;
+	qDebug() << "Successfully loaded UpdateChecker channel list.";
+
+	// If we're waiting to check for updates, do that now.
+	if (m_checkUpdateWaiting)
+		checkForUpdate(m_deferredUpdateChannel, notifyNoUpdate);
+
+	emit channelListLoaded();
+}
+
+void UpdateChecker::chanListDownloadFailed(QString reason)
+{
+	m_chanListLoading = false;
+	qCritical() << QString("Failed to download channel list: %1").arg(reason);
+	emit channelListLoaded();
+}
+
diff --git a/libraries/logic/updater/UpdateChecker.h b/libraries/logic/updater/UpdateChecker.h
new file mode 100644
index 00000000..c7fad10e
--- /dev/null
+++ b/libraries/logic/updater/UpdateChecker.h
@@ -0,0 +1,121 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "net/NetJob.h"
+#include "GoUpdate.h"
+
+#include <QUrl>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT UpdateChecker : public QObject
+{
+	Q_OBJECT
+
+public:
+	UpdateChecker(QString channelListUrl, QString currentChannel, int currentBuild);
+	void checkForUpdate(QString updateChannel, bool notifyNoUpdate);
+
+	/*!
+	 * Causes the update checker to download the channel list from the URL specified in config.h (generated by CMake).
+	 * If this isn't called before checkForUpdate(), it will automatically be called.
+	 */
+	void updateChanList(bool notifyNoUpdate);
+
+	/*!
+	 * An entry in the channel list.
+	 */
+	struct ChannelListEntry
+	{
+		QString id;
+		QString name;
+		QString description;
+		QString url;
+	};
+
+	/*!
+	 * Returns a the current channel list.
+	 * If the channel list hasn't been loaded, this list will be empty.
+	 */
+	QList<ChannelListEntry> getChannelList() const;
+
+	/*!
+	 * Returns false if the channel list is empty.
+	 */
+	bool hasChannels() const;
+
+signals:
+	//! Signal emitted when an update is available. Passes the URL for the repo and the ID and name for the version.
+	void updateAvailable(GoUpdate::Status status);
+
+	//! Signal emitted when the channel list finishes loading or fails to load.
+	void channelListLoaded();
+
+	void noUpdateFound();
+
+private slots:
+	void updateCheckFinished(bool notifyNoUpdate);
+	void updateCheckFailed();
+
+	void chanListDownloadFinished(bool notifyNoUpdate);
+	void chanListDownloadFailed(QString reason);
+
+private:
+	friend class UpdateCheckerTest;
+
+	NetJobPtr indexJob;
+	NetJobPtr chanListJob;
+
+	QString m_channelListUrl;
+
+	QList<ChannelListEntry> m_channels;
+
+	/*!
+	 * True while the system is checking for updates.
+	 * If checkForUpdate is called while this is true, it will be ignored.
+	 */
+	bool m_updateChecking;
+
+	/*!
+	 * True if the channel list has loaded.
+	 * If this is false, trying to check for updates will call updateChanList first.
+	 */
+	bool m_chanListLoaded;
+
+	/*!
+	 * Set to true while the channel list is currently loading.
+	 */
+	bool m_chanListLoading;
+
+	/*!
+	 * Set to true when checkForUpdate is called while the channel list isn't loaded.
+	 * When the channel list finishes loading, if this is true, the update checker will check for updates.
+	 */
+	bool m_checkUpdateWaiting;
+
+	/*!
+	 * if m_checkUpdateWaiting, this is the last used update channel
+	 */
+	QString m_deferredUpdateChannel;
+
+	int m_currentBuild = -1;
+	QString m_currentChannel;
+	QString m_currentRepoUrl;
+
+	QString m_newRepoUrl;
+};
+
diff --git a/libraries/logic/wonko/BaseWonkoEntity.cpp b/libraries/logic/wonko/BaseWonkoEntity.cpp
new file mode 100644
index 00000000..f5c59363
--- /dev/null
+++ b/libraries/logic/wonko/BaseWonkoEntity.cpp
@@ -0,0 +1,39 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseWonkoEntity.h"
+
+#include "Json.h"
+#include "WonkoUtil.h"
+
+BaseWonkoEntity::~BaseWonkoEntity()
+{
+}
+
+void BaseWonkoEntity::store() const
+{
+	Json::write(serialized(), Wonko::localWonkoDir().absoluteFilePath(localFilename()));
+}
+
+void BaseWonkoEntity::notifyLocalLoadComplete()
+{
+	m_localLoaded = true;
+	store();
+}
+void BaseWonkoEntity::notifyRemoteLoadComplete()
+{
+	m_remoteLoaded = true;
+	store();
+}
diff --git a/libraries/logic/wonko/BaseWonkoEntity.h b/libraries/logic/wonko/BaseWonkoEntity.h
new file mode 100644
index 00000000..191b4184
--- /dev/null
+++ b/libraries/logic/wonko/BaseWonkoEntity.h
@@ -0,0 +1,51 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <memory>
+
+#include "multimc_logic_export.h"
+
+class Task;
+
+class MULTIMC_LOGIC_EXPORT BaseWonkoEntity
+{
+public:
+	virtual ~BaseWonkoEntity();
+
+	using Ptr = std::shared_ptr<BaseWonkoEntity>;
+
+	virtual std::unique_ptr<Task> remoteUpdateTask() = 0;
+	virtual std::unique_ptr<Task> localUpdateTask() = 0;
+	virtual void merge(const std::shared_ptr<BaseWonkoEntity> &other) = 0;
+
+	void store() const;
+	virtual QString localFilename() const = 0;
+	virtual QJsonObject serialized() const = 0;
+
+	bool isComplete() const { return m_localLoaded || m_remoteLoaded; }
+
+	bool isLocalLoaded() const { return m_localLoaded; }
+	bool isRemoteLoaded() const { return m_remoteLoaded; }
+
+	void notifyLocalLoadComplete();
+	void notifyRemoteLoadComplete();
+
+private:
+	bool m_localLoaded = false;
+	bool m_remoteLoaded = false;
+};
diff --git a/libraries/logic/wonko/WonkoIndex.cpp b/libraries/logic/wonko/WonkoIndex.cpp
new file mode 100644
index 00000000..8306af84
--- /dev/null
+++ b/libraries/logic/wonko/WonkoIndex.cpp
@@ -0,0 +1,147 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoIndex.h"
+
+#include "WonkoVersionList.h"
+#include "tasks/BaseWonkoEntityLocalLoadTask.h"
+#include "tasks/BaseWonkoEntityRemoteLoadTask.h"
+#include "format/WonkoFormat.h"
+
+WonkoIndex::WonkoIndex(QObject *parent)
+	: QAbstractListModel(parent)
+{
+}
+WonkoIndex::WonkoIndex(const QVector<WonkoVersionListPtr> &lists, QObject *parent)
+	: QAbstractListModel(parent), m_lists(lists)
+{
+	for (int i = 0; i < m_lists.size(); ++i)
+	{
+		m_uids.insert(m_lists.at(i)->uid(), m_lists.at(i));
+		connectVersionList(i, m_lists.at(i));
+	}
+}
+
+QVariant WonkoIndex::data(const QModelIndex &index, int role) const
+{
+	if (index.parent().isValid() || index.row() < 0 || index.row() >= m_lists.size())
+	{
+		return QVariant();
+	}
+
+	WonkoVersionListPtr list = m_lists.at(index.row());
+	switch (role)
+	{
+	case Qt::DisplayRole:
+		switch (index.column())
+		{
+		case 0: return list->humanReadable();
+		default: break;
+		}
+	case UidRole: return list->uid();
+	case NameRole: return list->name();
+	case ListPtrRole: return QVariant::fromValue(list);
+	}
+	return QVariant();
+}
+int WonkoIndex::rowCount(const QModelIndex &parent) const
+{
+	return m_lists.size();
+}
+int WonkoIndex::columnCount(const QModelIndex &parent) const
+{
+	return 1;
+}
+QVariant WonkoIndex::headerData(int section, Qt::Orientation orientation, int role) const
+{
+	if (orientation == Qt::Horizontal && role == Qt::DisplayRole && section == 0)
+	{
+		return tr("Name");
+	}
+	else
+	{
+		return QVariant();
+	}
+}
+
+std::unique_ptr<Task> WonkoIndex::remoteUpdateTask()
+{
+	return std::unique_ptr<WonkoIndexRemoteLoadTask>(new WonkoIndexRemoteLoadTask(this, this));
+}
+std::unique_ptr<Task> WonkoIndex::localUpdateTask()
+{
+	return std::unique_ptr<WonkoIndexLocalLoadTask>(new WonkoIndexLocalLoadTask(this, this));
+}
+
+QJsonObject WonkoIndex::serialized() const
+{
+	return WonkoFormat::serializeIndex(this);
+}
+
+bool WonkoIndex::hasUid(const QString &uid) const
+{
+	return m_uids.contains(uid);
+}
+WonkoVersionListPtr WonkoIndex::getList(const QString &uid) const
+{
+	return m_uids.value(uid, nullptr);
+}
+WonkoVersionListPtr WonkoIndex::getListGuaranteed(const QString &uid) const
+{
+	return m_uids.value(uid, std::make_shared<WonkoVersionList>(uid));
+}
+
+void WonkoIndex::merge(const Ptr &other)
+{
+	const QVector<WonkoVersionListPtr> lists = std::dynamic_pointer_cast<WonkoIndex>(other)->m_lists;
+	// initial load, no need to merge
+	if (m_lists.isEmpty())
+	{
+		beginResetModel();
+		m_lists = lists;
+		for (int i = 0; i < lists.size(); ++i)
+		{
+			m_uids.insert(lists.at(i)->uid(), lists.at(i));
+			connectVersionList(i, lists.at(i));
+		}
+		endResetModel();
+	}
+	else
+	{
+		for (const WonkoVersionListPtr &list : lists)
+		{
+			if (m_uids.contains(list->uid()))
+			{
+				m_uids[list->uid()]->merge(list);
+			}
+			else
+			{
+				beginInsertRows(QModelIndex(), m_lists.size(), m_lists.size());
+				connectVersionList(m_lists.size(), list);
+				m_lists.append(list);
+				m_uids.insert(list->uid(), list);
+				endInsertRows();
+			}
+		}
+	}
+}
+
+void WonkoIndex::connectVersionList(const int row, const WonkoVersionListPtr &list)
+{
+	connect(list.get(), &WonkoVersionList::nameChanged, this, [this, row]()
+	{
+		emit dataChanged(index(row), index(row), QVector<int>() << Qt::DisplayRole);
+	});
+}
diff --git a/libraries/logic/wonko/WonkoIndex.h b/libraries/logic/wonko/WonkoIndex.h
new file mode 100644
index 00000000..8b149c7d
--- /dev/null
+++ b/libraries/logic/wonko/WonkoIndex.h
@@ -0,0 +1,68 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QAbstractListModel>
+#include <memory>
+
+#include "BaseWonkoEntity.h"
+
+#include "multimc_logic_export.h"
+
+class Task;
+using WonkoVersionListPtr = std::shared_ptr<class WonkoVersionList>;
+
+class MULTIMC_LOGIC_EXPORT WonkoIndex : public QAbstractListModel, public BaseWonkoEntity
+{
+	Q_OBJECT
+public:
+	explicit WonkoIndex(QObject *parent = nullptr);
+	explicit WonkoIndex(const QVector<WonkoVersionListPtr> &lists, QObject *parent = nullptr);
+
+	enum
+	{
+		UidRole = Qt::UserRole,
+		NameRole,
+		ListPtrRole
+	};
+
+	QVariant data(const QModelIndex &index, int role) const override;
+	int rowCount(const QModelIndex &parent) const override;
+	int columnCount(const QModelIndex &parent) const override;
+	QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+
+	std::unique_ptr<Task> remoteUpdateTask() override;
+	std::unique_ptr<Task> localUpdateTask() override;
+
+	QString localFilename() const override { return "index.json"; }
+	QJsonObject serialized() const override;
+
+	// queries
+	bool hasUid(const QString &uid) const;
+	WonkoVersionListPtr getList(const QString &uid) const;
+	WonkoVersionListPtr getListGuaranteed(const QString &uid) const;
+
+	QVector<WonkoVersionListPtr> lists() const { return m_lists; }
+
+public: // for usage by parsers only
+	void merge(const BaseWonkoEntity::Ptr &other);
+
+private:
+	QVector<WonkoVersionListPtr> m_lists;
+	QHash<QString, WonkoVersionListPtr> m_uids;
+
+	void connectVersionList(const int row, const WonkoVersionListPtr &list);
+};
diff --git a/libraries/logic/wonko/WonkoReference.cpp b/libraries/logic/wonko/WonkoReference.cpp
new file mode 100644
index 00000000..519d59aa
--- /dev/null
+++ b/libraries/logic/wonko/WonkoReference.cpp
@@ -0,0 +1,44 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoReference.h"
+
+WonkoReference::WonkoReference(const QString &uid)
+	: m_uid(uid)
+{
+}
+
+QString WonkoReference::uid() const
+{
+	return m_uid;
+}
+
+QString WonkoReference::version() const
+{
+	return m_version;
+}
+void WonkoReference::setVersion(const QString &version)
+{
+	m_version = version;
+}
+
+bool WonkoReference::operator==(const WonkoReference &other) const
+{
+	return m_uid == other.m_uid && m_version == other.m_version;
+}
+bool WonkoReference::operator!=(const WonkoReference &other) const
+{
+	return m_uid != other.m_uid || m_version != other.m_version;
+}
diff --git a/libraries/logic/wonko/WonkoReference.h b/libraries/logic/wonko/WonkoReference.h
new file mode 100644
index 00000000..73a85d76
--- /dev/null
+++ b/libraries/logic/wonko/WonkoReference.h
@@ -0,0 +1,41 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QMetaType>
+
+#include "multimc_logic_export.h"
+
+class MULTIMC_LOGIC_EXPORT WonkoReference
+{
+public:
+	WonkoReference() {}
+	explicit WonkoReference(const QString &uid);
+
+	QString uid() const;
+
+	QString version() const;
+	void setVersion(const QString &version);
+
+	bool operator==(const WonkoReference &other) const;
+	bool operator!=(const WonkoReference &other) const;
+
+private:
+	QString m_uid;
+	QString m_version;
+};
+Q_DECLARE_METATYPE(WonkoReference)
diff --git a/libraries/logic/wonko/WonkoUtil.cpp b/libraries/logic/wonko/WonkoUtil.cpp
new file mode 100644
index 00000000..94726c6b
--- /dev/null
+++ b/libraries/logic/wonko/WonkoUtil.cpp
@@ -0,0 +1,47 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoUtil.h"
+
+#include <QUrl>
+#include <QDir>
+
+#include "Env.h"
+
+namespace Wonko
+{
+QUrl rootUrl()
+{
+	return ENV.wonkoRootUrl();
+}
+QUrl indexUrl()
+{
+	return rootUrl().resolved(QStringLiteral("index.json"));
+}
+QUrl versionListUrl(const QString &uid)
+{
+	return rootUrl().resolved(uid + ".json");
+}
+QUrl versionUrl(const QString &uid, const QString &version)
+{
+	return rootUrl().resolved(uid + "/" + version + ".json");
+}
+
+QDir localWonkoDir()
+{
+	return QDir("wonko");
+}
+
+}
diff --git a/libraries/logic/wonko/WonkoUtil.h b/libraries/logic/wonko/WonkoUtil.h
new file mode 100644
index 00000000..b618ab71
--- /dev/null
+++ b/libraries/logic/wonko/WonkoUtil.h
@@ -0,0 +1,31 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "multimc_logic_export.h"
+
+class QUrl;
+class QString;
+class QDir;
+
+namespace Wonko
+{
+MULTIMC_LOGIC_EXPORT QUrl rootUrl();
+MULTIMC_LOGIC_EXPORT QUrl indexUrl();
+MULTIMC_LOGIC_EXPORT QUrl versionListUrl(const QString &uid);
+MULTIMC_LOGIC_EXPORT QUrl versionUrl(const QString &uid, const QString &version);
+MULTIMC_LOGIC_EXPORT QDir localWonkoDir();
+}
diff --git a/libraries/logic/wonko/WonkoVersion.cpp b/libraries/logic/wonko/WonkoVersion.cpp
new file mode 100644
index 00000000..7b7da86c
--- /dev/null
+++ b/libraries/logic/wonko/WonkoVersion.cpp
@@ -0,0 +1,102 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoVersion.h"
+
+#include <QDateTime>
+
+#include "tasks/BaseWonkoEntityLocalLoadTask.h"
+#include "tasks/BaseWonkoEntityRemoteLoadTask.h"
+#include "format/WonkoFormat.h"
+
+WonkoVersion::WonkoVersion(const QString &uid, const QString &version)
+	: BaseVersion(), m_uid(uid), m_version(version)
+{
+}
+
+QString WonkoVersion::descriptor()
+{
+	return m_version;
+}
+QString WonkoVersion::name()
+{
+	return m_version;
+}
+QString WonkoVersion::typeString() const
+{
+	return m_type;
+}
+
+QDateTime WonkoVersion::time() const
+{
+	return QDateTime::fromMSecsSinceEpoch(m_time * 1000, Qt::UTC);
+}
+
+std::unique_ptr<Task> WonkoVersion::remoteUpdateTask()
+{
+	return std::unique_ptr<WonkoVersionRemoteLoadTask>(new WonkoVersionRemoteLoadTask(this, this));
+}
+std::unique_ptr<Task> WonkoVersion::localUpdateTask()
+{
+	return std::unique_ptr<WonkoVersionLocalLoadTask>(new WonkoVersionLocalLoadTask(this, this));
+}
+
+void WonkoVersion::merge(const std::shared_ptr<BaseWonkoEntity> &other)
+{
+	WonkoVersionPtr version = std::dynamic_pointer_cast<WonkoVersion>(other);
+	if (m_type != version->m_type)
+	{
+		setType(version->m_type);
+	}
+	if (m_time != version->m_time)
+	{
+		setTime(version->m_time);
+	}
+	if (m_requires != version->m_requires)
+	{
+		setRequires(version->m_requires);
+	}
+
+	setData(version->m_data);
+}
+
+QString WonkoVersion::localFilename() const
+{
+	return m_uid + '/' + m_version + ".json";
+}
+QJsonObject WonkoVersion::serialized() const
+{
+	return WonkoFormat::serializeVersion(this);
+}
+
+void WonkoVersion::setType(const QString &type)
+{
+	m_type = type;
+	emit typeChanged();
+}
+void WonkoVersion::setTime(const qint64 time)
+{
+	m_time = time;
+	emit timeChanged();
+}
+void WonkoVersion::setRequires(const QVector<WonkoReference> &requires)
+{
+	m_requires = requires;
+	emit requiresChanged();
+}
+void WonkoVersion::setData(const VersionFilePtr &data)
+{
+	m_data = data;
+}
diff --git a/libraries/logic/wonko/WonkoVersion.h b/libraries/logic/wonko/WonkoVersion.h
new file mode 100644
index 00000000..a1de4d9b
--- /dev/null
+++ b/libraries/logic/wonko/WonkoVersion.h
@@ -0,0 +1,83 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "BaseVersion.h"
+#include "BaseWonkoEntity.h"
+
+#include <QVector>
+#include <QStringList>
+#include <QJsonObject>
+#include <memory>
+
+#include "minecraft/VersionFile.h"
+#include "WonkoReference.h"
+
+#include "multimc_logic_export.h"
+
+using WonkoVersionPtr = std::shared_ptr<class WonkoVersion>;
+
+class MULTIMC_LOGIC_EXPORT WonkoVersion : public QObject, public BaseVersion, public BaseWonkoEntity
+{
+	Q_OBJECT
+	Q_PROPERTY(QString uid READ uid CONSTANT)
+	Q_PROPERTY(QString version READ version CONSTANT)
+	Q_PROPERTY(QString type READ type NOTIFY typeChanged)
+	Q_PROPERTY(QDateTime time READ time NOTIFY timeChanged)
+	Q_PROPERTY(QVector<WonkoReference> requires READ requires NOTIFY requiresChanged)
+public:
+	explicit WonkoVersion(const QString &uid, const QString &version);
+
+	QString descriptor() override;
+	QString name() override;
+	QString typeString() const override;
+
+	QString uid() const { return m_uid; }
+	QString version() const { return m_version; }
+	QString type() const { return m_type; }
+	QDateTime time() const;
+	qint64 rawTime() const { return m_time; }
+	QVector<WonkoReference> requires() const { return m_requires; }
+	VersionFilePtr data() const { return m_data; }
+
+	std::unique_ptr<Task> remoteUpdateTask() override;
+	std::unique_ptr<Task> localUpdateTask() override;
+	void merge(const std::shared_ptr<BaseWonkoEntity> &other) override;
+
+	QString localFilename() const override;
+	QJsonObject serialized() const override;
+
+public: // for usage by format parsers only
+	void setType(const QString &type);
+	void setTime(const qint64 time);
+	void setRequires(const QVector<WonkoReference> &requires);
+	void setData(const VersionFilePtr &data);
+
+signals:
+	void typeChanged();
+	void timeChanged();
+	void requiresChanged();
+
+private:
+	QString m_uid;
+	QString m_version;
+	QString m_type;
+	qint64 m_time;
+	QVector<WonkoReference> m_requires;
+	VersionFilePtr m_data;
+};
+
+Q_DECLARE_METATYPE(WonkoVersionPtr)
diff --git a/libraries/logic/wonko/WonkoVersionList.cpp b/libraries/logic/wonko/WonkoVersionList.cpp
new file mode 100644
index 00000000..e9d79327
--- /dev/null
+++ b/libraries/logic/wonko/WonkoVersionList.cpp
@@ -0,0 +1,283 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoVersionList.h"
+
+#include <QDateTime>
+
+#include "WonkoVersion.h"
+#include "tasks/BaseWonkoEntityRemoteLoadTask.h"
+#include "tasks/BaseWonkoEntityLocalLoadTask.h"
+#include "format/WonkoFormat.h"
+#include "WonkoReference.h"
+
+class WVLLoadTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit WVLLoadTask(WonkoVersionList *list, QObject *parent = nullptr)
+		: Task(parent), m_list(list)
+	{
+	}
+
+	bool canAbort() const override
+	{
+		return !m_currentTask || m_currentTask->canAbort();
+	}
+	bool abort() override
+	{
+		return m_currentTask->abort();
+	}
+
+private:
+	void executeTask() override
+	{
+		if (!m_list->isLocalLoaded())
+		{
+			m_currentTask = m_list->localUpdateTask();
+			connect(m_currentTask.get(), &Task::succeeded, this, &WVLLoadTask::next);
+		}
+		else
+		{
+			m_currentTask = m_list->remoteUpdateTask();
+			connect(m_currentTask.get(), &Task::succeeded, this, &WVLLoadTask::emitSucceeded);
+		}
+		connect(m_currentTask.get(), &Task::status, this, &WVLLoadTask::setStatus);
+		connect(m_currentTask.get(), &Task::progress, this, &WVLLoadTask::setProgress);
+		connect(m_currentTask.get(), &Task::failed, this, &WVLLoadTask::emitFailed);
+		m_currentTask->start();
+	}
+
+	void next()
+	{
+		m_currentTask = m_list->remoteUpdateTask();
+		connect(m_currentTask.get(), &Task::status, this, &WVLLoadTask::setStatus);
+		connect(m_currentTask.get(), &Task::progress, this, &WVLLoadTask::setProgress);
+		connect(m_currentTask.get(), &Task::succeeded, this, &WVLLoadTask::emitSucceeded);
+		m_currentTask->start();
+	}
+
+	WonkoVersionList *m_list;
+	std::unique_ptr<Task> m_currentTask;
+};
+
+WonkoVersionList::WonkoVersionList(const QString &uid, QObject *parent)
+	: BaseVersionList(parent), m_uid(uid)
+{
+	setObjectName("Wonko version list: " + uid);
+}
+
+Task *WonkoVersionList::getLoadTask()
+{
+	return new WVLLoadTask(this);
+}
+
+bool WonkoVersionList::isLoaded()
+{
+	return isLocalLoaded() && isRemoteLoaded();
+}
+
+const BaseVersionPtr WonkoVersionList::at(int i) const
+{
+	return m_versions.at(i);
+}
+int WonkoVersionList::count() const
+{
+	return m_versions.size();
+}
+
+void WonkoVersionList::sortVersions()
+{
+	beginResetModel();
+	std::sort(m_versions.begin(), m_versions.end(), [](const WonkoVersionPtr &a, const WonkoVersionPtr &b)
+	{
+		return *a.get() < *b.get();
+	});
+	endResetModel();
+}
+
+QVariant WonkoVersionList::data(const QModelIndex &index, int role) const
+{
+	if (!index.isValid() || index.row() < 0 || index.row() >= m_versions.size() || index.parent().isValid())
+	{
+		return QVariant();
+	}
+
+	WonkoVersionPtr version = m_versions.at(index.row());
+
+	switch (role)
+	{
+	case VersionPointerRole: return QVariant::fromValue(std::dynamic_pointer_cast<BaseVersion>(version));
+	case VersionRole:
+	case VersionIdRole:
+		return version->version();
+	case ParentGameVersionRole:
+	{
+		const auto end = version->requires().end();
+		const auto it = std::find_if(version->requires().begin(), end,
+									 [](const WonkoReference &ref) { return ref.uid() == "net.minecraft"; });
+		if (it != end)
+		{
+			return (*it).version();
+		}
+		return QVariant();
+	}
+	case TypeRole: return version->type();
+
+	case UidRole: return version->uid();
+	case TimeRole: return version->time();
+	case RequiresRole: return QVariant::fromValue(version->requires());
+	case SortRole: return version->rawTime();
+	case WonkoVersionPtrRole: return QVariant::fromValue(version);
+	case RecommendedRole: return version == getRecommended();
+	case LatestRole: return version == getLatestStable();
+	default: return QVariant();
+	}
+}
+
+BaseVersionList::RoleList WonkoVersionList::providesRoles() const
+{
+	return {VersionPointerRole, VersionRole, VersionIdRole, ParentGameVersionRole,
+				TypeRole, UidRole, TimeRole, RequiresRole, SortRole,
+				RecommendedRole, LatestRole, WonkoVersionPtrRole};
+}
+
+QHash<int, QByteArray> WonkoVersionList::roleNames() const
+{
+	QHash<int, QByteArray> roles = BaseVersionList::roleNames();
+	roles.insert(UidRole, "uid");
+	roles.insert(TimeRole, "time");
+	roles.insert(SortRole, "sort");
+	roles.insert(RequiresRole, "requires");
+	return roles;
+}
+
+std::unique_ptr<Task> WonkoVersionList::remoteUpdateTask()
+{
+	return std::unique_ptr<WonkoVersionListRemoteLoadTask>(new WonkoVersionListRemoteLoadTask(this, this));
+}
+std::unique_ptr<Task> WonkoVersionList::localUpdateTask()
+{
+	return std::unique_ptr<WonkoVersionListLocalLoadTask>(new WonkoVersionListLocalLoadTask(this, this));
+}
+
+QString WonkoVersionList::localFilename() const
+{
+	return m_uid + ".json";
+}
+QJsonObject WonkoVersionList::serialized() const
+{
+	return WonkoFormat::serializeVersionList(this);
+}
+
+QString WonkoVersionList::humanReadable() const
+{
+	return m_name.isEmpty() ? m_uid : m_name;
+}
+
+bool WonkoVersionList::hasVersion(const QString &version) const
+{
+	return m_lookup.contains(version);
+}
+WonkoVersionPtr WonkoVersionList::getVersion(const QString &version) const
+{
+	return m_lookup.value(version);
+}
+
+void WonkoVersionList::setName(const QString &name)
+{
+	m_name = name;
+	emit nameChanged(name);
+}
+void WonkoVersionList::setVersions(const QVector<WonkoVersionPtr> &versions)
+{
+	beginResetModel();
+	m_versions = versions;
+	std::sort(m_versions.begin(), m_versions.end(), [](const WonkoVersionPtr &a, const WonkoVersionPtr &b)
+	{
+		return a->rawTime() > b->rawTime();
+	});
+	for (int i = 0; i < m_versions.size(); ++i)
+	{
+		m_lookup.insert(m_versions.at(i)->version(), m_versions.at(i));
+		setupAddedVersion(i, m_versions.at(i));
+	}
+
+	m_latest = m_versions.isEmpty() ? nullptr : m_versions.first();
+	auto recommendedIt = std::find_if(m_versions.constBegin(), m_versions.constEnd(), [](const WonkoVersionPtr &ptr) { return ptr->type() == "release"; });
+	m_recommended = recommendedIt == m_versions.constEnd() ? nullptr : *recommendedIt;
+	endResetModel();
+}
+
+void WonkoVersionList::merge(const BaseWonkoEntity::Ptr &other)
+{
+	const WonkoVersionListPtr list = std::dynamic_pointer_cast<WonkoVersionList>(other);
+	if (m_name != list->m_name)
+	{
+		setName(list->m_name);
+	}
+
+	if (m_versions.isEmpty())
+	{
+		setVersions(list->m_versions);
+	}
+	else
+	{
+		for (const WonkoVersionPtr &version : list->m_versions)
+		{
+			if (m_lookup.contains(version->version()))
+			{
+				m_lookup.value(version->version())->merge(version);
+			}
+			else
+			{
+				beginInsertRows(QModelIndex(), m_versions.size(), m_versions.size());
+				setupAddedVersion(m_versions.size(), version);
+				m_versions.append(version);
+				m_lookup.insert(version->uid(), version);
+				endInsertRows();
+
+				if (!m_latest || version->rawTime() > m_latest->rawTime())
+				{
+					m_latest = version;
+					emit dataChanged(index(0), index(m_versions.size() - 1), QVector<int>() << LatestRole);
+				}
+				if (!m_recommended || (version->type() == "release" && version->rawTime() > m_recommended->rawTime()))
+				{
+					m_recommended = version;
+					emit dataChanged(index(0), index(m_versions.size() - 1), QVector<int>() << RecommendedRole);
+				}
+			}
+		}
+	}
+}
+
+void WonkoVersionList::setupAddedVersion(const int row, const WonkoVersionPtr &version)
+{
+	connect(version.get(), &WonkoVersion::requiresChanged, this, [this, row]() { emit dataChanged(index(row), index(row), QVector<int>() << RequiresRole); });
+	connect(version.get(), &WonkoVersion::timeChanged, this, [this, row]() { emit dataChanged(index(row), index(row), QVector<int>() << TimeRole << SortRole); });
+	connect(version.get(), &WonkoVersion::typeChanged, this, [this, row]() { emit dataChanged(index(row), index(row), QVector<int>() << TypeRole); });
+}
+
+BaseVersionPtr WonkoVersionList::getLatestStable() const
+{
+	return m_latest;
+}
+BaseVersionPtr WonkoVersionList::getRecommended() const
+{
+	return m_recommended;
+}
+
+#include "WonkoVersionList.moc"
diff --git a/libraries/logic/wonko/WonkoVersionList.h b/libraries/logic/wonko/WonkoVersionList.h
new file mode 100644
index 00000000..8ea35be6
--- /dev/null
+++ b/libraries/logic/wonko/WonkoVersionList.h
@@ -0,0 +1,92 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "BaseVersionList.h"
+#include "BaseWonkoEntity.h"
+#include <memory>
+
+using WonkoVersionPtr = std::shared_ptr<class WonkoVersion>;
+using WonkoVersionListPtr = std::shared_ptr<class WonkoVersionList>;
+
+class MULTIMC_LOGIC_EXPORT WonkoVersionList : public BaseVersionList, public BaseWonkoEntity
+{
+	Q_OBJECT
+	Q_PROPERTY(QString uid READ uid CONSTANT)
+	Q_PROPERTY(QString name READ name NOTIFY nameChanged)
+public:
+	explicit WonkoVersionList(const QString &uid, QObject *parent = nullptr);
+
+	enum Roles
+	{
+		UidRole = Qt::UserRole + 100,
+		TimeRole,
+		RequiresRole,
+		WonkoVersionPtrRole
+	};
+
+	Task *getLoadTask() override;
+	bool isLoaded() override;
+	const BaseVersionPtr at(int i) const override;
+	int count() const override;
+	void sortVersions() override;
+
+	BaseVersionPtr getLatestStable() const override;
+	BaseVersionPtr getRecommended() const override;
+
+	QVariant data(const QModelIndex &index, int role) const override;
+	RoleList providesRoles() const override;
+	QHash<int, QByteArray> roleNames() const override;
+
+	std::unique_ptr<Task> remoteUpdateTask() override;
+	std::unique_ptr<Task> localUpdateTask() override;
+
+	QString localFilename() const override;
+	QJsonObject serialized() const override;
+
+	QString uid() const { return m_uid; }
+	QString name() const { return m_name; }
+	QString humanReadable() const;
+
+	bool hasVersion(const QString &version) const;
+	WonkoVersionPtr getVersion(const QString &version) const;
+
+	QVector<WonkoVersionPtr> versions() const { return m_versions; }
+
+public: // for usage only by parsers
+	void setName(const QString &name);
+	void setVersions(const QVector<WonkoVersionPtr> &versions);
+	void merge(const BaseWonkoEntity::Ptr &other);
+
+signals:
+	void nameChanged(const QString &name);
+
+protected slots:
+	void updateListData(QList<BaseVersionPtr> versions) override {}
+
+private:
+	QVector<WonkoVersionPtr> m_versions;
+	QHash<QString, WonkoVersionPtr> m_lookup;
+	QString m_uid;
+	QString m_name;
+
+	WonkoVersionPtr m_recommended;
+	WonkoVersionPtr m_latest;
+
+	void setupAddedVersion(const int row, const WonkoVersionPtr &version);
+};
+
+Q_DECLARE_METATYPE(WonkoVersionListPtr)
diff --git a/libraries/logic/wonko/format/WonkoFormat.cpp b/libraries/logic/wonko/format/WonkoFormat.cpp
new file mode 100644
index 00000000..11192cbe
--- /dev/null
+++ b/libraries/logic/wonko/format/WonkoFormat.cpp
@@ -0,0 +1,80 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoFormat.h"
+
+#include "WonkoFormatV1.h"
+
+#include "wonko/WonkoIndex.h"
+#include "wonko/WonkoVersion.h"
+#include "wonko/WonkoVersionList.h"
+
+static int formatVersion(const QJsonObject &obj)
+{
+	if (!obj.contains("formatVersion")) {
+		throw WonkoParseException(QObject::tr("Missing required field: 'formatVersion'"));
+	}
+	if (!obj.value("formatVersion").isDouble()) {
+		throw WonkoParseException(QObject::tr("Required field has invalid type: 'formatVersion'"));
+	}
+	return obj.value("formatVersion").toInt();
+}
+
+void WonkoFormat::parseIndex(const QJsonObject &obj, WonkoIndex *ptr)
+{
+	const int version = formatVersion(obj);
+	switch (version) {
+	case 1:
+		ptr->merge(WonkoFormatV1().parseIndexInternal(obj));
+		break;
+	default:
+		throw WonkoParseException(QObject::tr("Unknown formatVersion: %1").arg(version));
+	}
+}
+void WonkoFormat::parseVersion(const QJsonObject &obj, WonkoVersion *ptr)
+{
+	const int version = formatVersion(obj);
+	switch (version) {
+	case 1:
+		ptr->merge(WonkoFormatV1().parseVersionInternal(obj));
+		break;
+	default:
+		throw WonkoParseException(QObject::tr("Unknown formatVersion: %1").arg(version));
+	}
+}
+void WonkoFormat::parseVersionList(const QJsonObject &obj, WonkoVersionList *ptr)
+{
+	const int version = formatVersion(obj);
+	switch (version) {
+	case 10:
+		ptr->merge(WonkoFormatV1().parseVersionListInternal(obj));
+		break;
+	default:
+		throw WonkoParseException(QObject::tr("Unknown formatVersion: %1").arg(version));
+	}
+}
+
+QJsonObject WonkoFormat::serializeIndex(const WonkoIndex *ptr)
+{
+	return WonkoFormatV1().serializeIndexInternal(ptr);
+}
+QJsonObject WonkoFormat::serializeVersion(const WonkoVersion *ptr)
+{
+	return WonkoFormatV1().serializeVersionInternal(ptr);
+}
+QJsonObject WonkoFormat::serializeVersionList(const WonkoVersionList *ptr)
+{
+	return WonkoFormatV1().serializeVersionListInternal(ptr);
+}
diff --git a/libraries/logic/wonko/format/WonkoFormat.h b/libraries/logic/wonko/format/WonkoFormat.h
new file mode 100644
index 00000000..450d6ccc
--- /dev/null
+++ b/libraries/logic/wonko/format/WonkoFormat.h
@@ -0,0 +1,54 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QJsonObject>
+#include <memory>
+
+#include "Exception.h"
+#include "wonko/BaseWonkoEntity.h"
+
+class WonkoIndex;
+class WonkoVersion;
+class WonkoVersionList;
+
+class WonkoParseException : public Exception
+{
+public:
+	using Exception::Exception;
+};
+
+class WonkoFormat
+{
+public:
+	virtual ~WonkoFormat() {}
+
+	static void parseIndex(const QJsonObject &obj, WonkoIndex *ptr);
+	static void parseVersion(const QJsonObject &obj, WonkoVersion *ptr);
+	static void parseVersionList(const QJsonObject &obj, WonkoVersionList *ptr);
+
+	static QJsonObject serializeIndex(const WonkoIndex *ptr);
+	static QJsonObject serializeVersion(const WonkoVersion *ptr);
+	static QJsonObject serializeVersionList(const WonkoVersionList *ptr);
+
+protected:
+	virtual BaseWonkoEntity::Ptr parseIndexInternal(const QJsonObject &obj) const = 0;
+	virtual BaseWonkoEntity::Ptr parseVersionInternal(const QJsonObject &obj) const = 0;
+	virtual BaseWonkoEntity::Ptr parseVersionListInternal(const QJsonObject &obj) const = 0;
+	virtual QJsonObject serializeIndexInternal(const WonkoIndex *ptr) const = 0;
+	virtual QJsonObject serializeVersionInternal(const WonkoVersion *ptr) const = 0;
+	virtual QJsonObject serializeVersionListInternal(const WonkoVersionList *ptr) const = 0;
+};
diff --git a/libraries/logic/wonko/format/WonkoFormatV1.cpp b/libraries/logic/wonko/format/WonkoFormatV1.cpp
new file mode 100644
index 00000000..363eebfb
--- /dev/null
+++ b/libraries/logic/wonko/format/WonkoFormatV1.cpp
@@ -0,0 +1,156 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "WonkoFormatV1.h"
+#include <minecraft/onesix/OneSixVersionFormat.h>
+
+#include "Json.h"
+
+#include "wonko/WonkoIndex.h"
+#include "wonko/WonkoVersion.h"
+#include "wonko/WonkoVersionList.h"
+#include "Env.h"
+
+using namespace Json;
+
+static WonkoVersionPtr parseCommonVersion(const QString &uid, const QJsonObject &obj)
+{
+	const QVector<QJsonObject> requiresRaw = obj.contains("requires") ? requireIsArrayOf<QJsonObject>(obj, "requires") : QVector<QJsonObject>();
+	QVector<WonkoReference> requires;
+	requires.reserve(requiresRaw.size());
+	std::transform(requiresRaw.begin(), requiresRaw.end(), std::back_inserter(requires), [](const QJsonObject &rObj)
+	{
+		WonkoReference ref(requireString(rObj, "uid"));
+		ref.setVersion(ensureString(rObj, "version", QString()));
+		return ref;
+	});
+
+	WonkoVersionPtr version = std::make_shared<WonkoVersion>(uid, requireString(obj, "version"));
+	if (obj.value("time").isString())
+	{
+		version->setTime(QDateTime::fromString(requireString(obj, "time"), Qt::ISODate).toMSecsSinceEpoch() / 1000);
+	}
+	else
+	{
+		version->setTime(requireInteger(obj, "time"));
+	}
+	version->setType(ensureString(obj, "type", QString()));
+	version->setRequires(requires);
+	return version;
+}
+static void serializeCommonVersion(const WonkoVersion *version, QJsonObject &obj)
+{
+	QJsonArray requires;
+	for (const WonkoReference &ref : version->requires())
+	{
+		if (ref.version().isEmpty())
+		{
+			requires.append(QJsonObject({{"uid", ref.uid()}}));
+		}
+		else
+		{
+			requires.append(QJsonObject({
+											{"uid", ref.uid()},
+											{"version", ref.version()}
+										}));
+		}
+	}
+
+	obj.insert("version", version->version());
+	obj.insert("type", version->type());
+	obj.insert("time", version->time().toString(Qt::ISODate));
+	obj.insert("requires", requires);
+}
+
+BaseWonkoEntity::Ptr WonkoFormatV1::parseIndexInternal(const QJsonObject &obj) const
+{
+	const QVector<QJsonObject> objects = requireIsArrayOf<QJsonObject>(obj, "index");
+	QVector<WonkoVersionListPtr> lists;
+	lists.reserve(objects.size());
+	std::transform(objects.begin(), objects.end(), std::back_inserter(lists), [](const QJsonObject &obj)
+	{
+		WonkoVersionListPtr list = std::make_shared<WonkoVersionList>(requireString(obj, "uid"));
+		list->setName(ensureString(obj, "name", QString()));
+		return list;
+	});
+	return std::make_shared<WonkoIndex>(lists);
+}
+BaseWonkoEntity::Ptr WonkoFormatV1::parseVersionInternal(const QJsonObject &obj) const
+{
+	WonkoVersionPtr version = parseCommonVersion(requireString(obj, "uid"), obj);
+
+	version->setData(OneSixVersionFormat::versionFileFromJson(QJsonDocument(obj),
+										   QString("%1/%2.json").arg(version->uid(), version->version()),
+										   obj.contains("order")));
+	return version;
+}
+BaseWonkoEntity::Ptr WonkoFormatV1::parseVersionListInternal(const QJsonObject &obj) const
+{
+	const QString uid = requireString(obj, "uid");
+
+	const QVector<QJsonObject> versionsRaw = requireIsArrayOf<QJsonObject>(obj, "versions");
+	QVector<WonkoVersionPtr> versions;
+	versions.reserve(versionsRaw.size());
+	std::transform(versionsRaw.begin(), versionsRaw.end(), std::back_inserter(versions), [this, uid](const QJsonObject &vObj)
+	{ return parseCommonVersion(uid, vObj); });
+
+	WonkoVersionListPtr list = std::make_shared<WonkoVersionList>(uid);
+	list->setName(ensureString(obj, "name", QString()));
+	list->setVersions(versions);
+	return list;
+}
+
+QJsonObject WonkoFormatV1::serializeIndexInternal(const WonkoIndex *ptr) const
+{
+	QJsonArray index;
+	for (const WonkoVersionListPtr &list : ptr->lists())
+	{
+		index.append(QJsonObject({
+									 {"uid", list->uid()},
+									 {"name", list->name()}
+								 }));
+	}
+	return QJsonObject({
+						   {"formatVersion", 1},
+						   {"index", index}
+					   });
+}
+QJsonObject WonkoFormatV1::serializeVersionInternal(const WonkoVersion *ptr) const
+{
+	QJsonObject obj = OneSixVersionFormat::versionFileToJson(ptr->data(), true).object();
+	serializeCommonVersion(ptr, obj);
+	obj.insert("formatVersion", 1);
+	obj.insert("uid", ptr->uid());
+	// TODO: the name should be looked up in the UI based on the uid
+	obj.insert("name", ENV.wonkoIndex()->getListGuaranteed(ptr->uid())->name());
+
+	return obj;
+}
+QJsonObject WonkoFormatV1::serializeVersionListInternal(const WonkoVersionList *ptr) const
+{
+	QJsonArray versions;
+	for (const WonkoVersionPtr &version : ptr->versions())
+	{
+		QJsonObject obj;
+		serializeCommonVersion(version.get(), obj);
+		versions.append(obj);
+	}
+	return QJsonObject({
+						   {"formatVersion", 10},
+						   {"uid", ptr->uid()},
+						   {"name", ptr->name().isNull() ? QJsonValue() : ptr->name()},
+						   {"versions", versions}
+					   });
+}
diff --git a/libraries/logic/wonko/format/WonkoFormatV1.h b/libraries/logic/wonko/format/WonkoFormatV1.h
new file mode 100644
index 00000000..92759804
--- /dev/null
+++ b/libraries/logic/wonko/format/WonkoFormatV1.h
@@ -0,0 +1,30 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "WonkoFormat.h"
+
+class WonkoFormatV1 : public WonkoFormat
+{
+public:
+	BaseWonkoEntity::Ptr parseIndexInternal(const QJsonObject &obj) const override;
+	BaseWonkoEntity::Ptr parseVersionInternal(const QJsonObject &obj) const override;
+	BaseWonkoEntity::Ptr parseVersionListInternal(const QJsonObject &obj) const override;
+
+	QJsonObject serializeIndexInternal(const WonkoIndex *ptr) const override;
+	QJsonObject serializeVersionInternal(const WonkoVersion *ptr) const override;
+	QJsonObject serializeVersionListInternal(const WonkoVersionList *ptr) const override;
+};
diff --git a/libraries/logic/wonko/tasks/BaseWonkoEntityLocalLoadTask.cpp b/libraries/logic/wonko/tasks/BaseWonkoEntityLocalLoadTask.cpp
new file mode 100644
index 00000000..b54c592f
--- /dev/null
+++ b/libraries/logic/wonko/tasks/BaseWonkoEntityLocalLoadTask.cpp
@@ -0,0 +1,117 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseWonkoEntityLocalLoadTask.h"
+
+#include <QFile>
+
+#include "wonko/format/WonkoFormat.h"
+#include "wonko/WonkoUtil.h"
+#include "wonko/WonkoIndex.h"
+#include "wonko/WonkoVersion.h"
+#include "wonko/WonkoVersionList.h"
+#include "Env.h"
+#include "Json.h"
+
+BaseWonkoEntityLocalLoadTask::BaseWonkoEntityLocalLoadTask(BaseWonkoEntity *entity, QObject *parent)
+	: Task(parent), m_entity(entity)
+{
+}
+
+void BaseWonkoEntityLocalLoadTask::executeTask()
+{
+	const QString fname = Wonko::localWonkoDir().absoluteFilePath(filename());
+	if (!QFile::exists(fname))
+	{
+		emitFailed(tr("File doesn't exist"));
+		return;
+	}
+
+	setStatus(tr("Reading %1...").arg(name()));
+	setProgress(0, 0);
+
+	try
+	{
+		parse(Json::requireObject(Json::requireDocument(fname, name()), name()));
+		m_entity->notifyLocalLoadComplete();
+		emitSucceeded();
+	}
+	catch (Exception &e)
+	{
+		emitFailed(tr("Unable to parse file %1: %2").arg(fname, e.cause()));
+	}
+}
+
+//      WONKO INDEX      //
+WonkoIndexLocalLoadTask::WonkoIndexLocalLoadTask(WonkoIndex *index, QObject *parent)
+	: BaseWonkoEntityLocalLoadTask(index, parent)
+{
+}
+QString WonkoIndexLocalLoadTask::filename() const
+{
+	return "index.json";
+}
+QString WonkoIndexLocalLoadTask::name() const
+{
+	return tr("Wonko Index");
+}
+void WonkoIndexLocalLoadTask::parse(const QJsonObject &obj) const
+{
+	WonkoFormat::parseIndex(obj, dynamic_cast<WonkoIndex *>(entity()));
+}
+
+//      WONKO VERSION LIST      //
+WonkoVersionListLocalLoadTask::WonkoVersionListLocalLoadTask(WonkoVersionList *list, QObject *parent)
+	: BaseWonkoEntityLocalLoadTask(list, parent)
+{
+}
+QString WonkoVersionListLocalLoadTask::filename() const
+{
+	return list()->uid() + ".json";
+}
+QString WonkoVersionListLocalLoadTask::name() const
+{
+	return tr("Wonko Version List for %1").arg(list()->humanReadable());
+}
+void WonkoVersionListLocalLoadTask::parse(const QJsonObject &obj) const
+{
+	WonkoFormat::parseVersionList(obj, list());
+}
+WonkoVersionList *WonkoVersionListLocalLoadTask::list() const
+{
+	return dynamic_cast<WonkoVersionList *>(entity());
+}
+
+//      WONKO VERSION      //
+WonkoVersionLocalLoadTask::WonkoVersionLocalLoadTask(WonkoVersion *version, QObject *parent)
+	: BaseWonkoEntityLocalLoadTask(version, parent)
+{
+}
+QString WonkoVersionLocalLoadTask::filename() const
+{
+	return version()->uid() + "/" + version()->version() + ".json";
+}
+QString WonkoVersionLocalLoadTask::name() const
+{
+	return tr("Wonko Version for %1").arg(version()->name());
+}
+void WonkoVersionLocalLoadTask::parse(const QJsonObject &obj) const
+{
+	WonkoFormat::parseVersion(obj, version());
+}
+WonkoVersion *WonkoVersionLocalLoadTask::version() const
+{
+	return dynamic_cast<WonkoVersion *>(entity());
+}
diff --git a/libraries/logic/wonko/tasks/BaseWonkoEntityLocalLoadTask.h b/libraries/logic/wonko/tasks/BaseWonkoEntityLocalLoadTask.h
new file mode 100644
index 00000000..2affa17f
--- /dev/null
+++ b/libraries/logic/wonko/tasks/BaseWonkoEntityLocalLoadTask.h
@@ -0,0 +1,81 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "tasks/Task.h"
+#include <memory>
+
+class BaseWonkoEntity;
+class WonkoIndex;
+class WonkoVersionList;
+class WonkoVersion;
+
+class BaseWonkoEntityLocalLoadTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit BaseWonkoEntityLocalLoadTask(BaseWonkoEntity *entity, QObject *parent = nullptr);
+
+protected:
+	virtual QString filename() const = 0;
+	virtual QString name() const = 0;
+	virtual void parse(const QJsonObject &obj) const = 0;
+
+	BaseWonkoEntity *entity() const { return m_entity; }
+
+private:
+	void executeTask() override;
+
+	BaseWonkoEntity *m_entity;
+};
+
+class WonkoIndexLocalLoadTask : public BaseWonkoEntityLocalLoadTask
+{
+	Q_OBJECT
+public:
+	explicit WonkoIndexLocalLoadTask(WonkoIndex *index, QObject *parent = nullptr);
+
+private:
+	QString filename() const override;
+	QString name() const override;
+	void parse(const QJsonObject &obj) const override;
+};
+class WonkoVersionListLocalLoadTask : public BaseWonkoEntityLocalLoadTask
+{
+	Q_OBJECT
+public:
+	explicit WonkoVersionListLocalLoadTask(WonkoVersionList *list, QObject *parent = nullptr);
+
+private:
+	QString filename() const override;
+	QString name() const override;
+	void parse(const QJsonObject &obj) const override;
+
+	WonkoVersionList *list() const;
+};
+class WonkoVersionLocalLoadTask : public BaseWonkoEntityLocalLoadTask
+{
+	Q_OBJECT
+public:
+	explicit WonkoVersionLocalLoadTask(WonkoVersion *version, QObject *parent = nullptr);
+
+private:
+	QString filename() const override;
+	QString name() const override;
+	void parse(const QJsonObject &obj) const override;
+
+	WonkoVersion *version() const;
+};
diff --git a/libraries/logic/wonko/tasks/BaseWonkoEntityRemoteLoadTask.cpp b/libraries/logic/wonko/tasks/BaseWonkoEntityRemoteLoadTask.cpp
new file mode 100644
index 00000000..727ec89d
--- /dev/null
+++ b/libraries/logic/wonko/tasks/BaseWonkoEntityRemoteLoadTask.cpp
@@ -0,0 +1,126 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseWonkoEntityRemoteLoadTask.h"
+
+#include "net/CacheDownload.h"
+#include "net/HttpMetaCache.h"
+#include "net/NetJob.h"
+#include "wonko/format/WonkoFormat.h"
+#include "wonko/WonkoUtil.h"
+#include "wonko/WonkoIndex.h"
+#include "wonko/WonkoVersion.h"
+#include "wonko/WonkoVersionList.h"
+#include "Env.h"
+#include "Json.h"
+
+BaseWonkoEntityRemoteLoadTask::BaseWonkoEntityRemoteLoadTask(BaseWonkoEntity *entity, QObject *parent)
+	: Task(parent), m_entity(entity)
+{
+}
+
+void BaseWonkoEntityRemoteLoadTask::executeTask()
+{
+	NetJob *job = new NetJob(name());
+
+	auto entry = ENV.metacache()->resolveEntry("wonko", url().toString());
+	entry->setStale(true);
+	m_dl = CacheDownload::make(url(), entry);
+	job->addNetAction(m_dl);
+	connect(job, &NetJob::failed, this, &BaseWonkoEntityRemoteLoadTask::emitFailed);
+	connect(job, &NetJob::succeeded, this, &BaseWonkoEntityRemoteLoadTask::networkFinished);
+	connect(job, &NetJob::status, this, &BaseWonkoEntityRemoteLoadTask::setStatus);
+	connect(job, &NetJob::progress, this, &BaseWonkoEntityRemoteLoadTask::setProgress);
+	job->start();
+}
+
+void BaseWonkoEntityRemoteLoadTask::networkFinished()
+{
+	setStatus(tr("Parsing..."));
+	setProgress(0, 0);
+
+	try
+	{
+		parse(Json::requireObject(Json::requireDocument(m_dl->getTargetFilepath(), name()), name()));
+		m_entity->notifyRemoteLoadComplete();
+		emitSucceeded();
+	}
+	catch (Exception &e)
+	{
+		emitFailed(tr("Unable to parse response: %1").arg(e.cause()));
+	}
+}
+
+//      WONKO INDEX      //
+WonkoIndexRemoteLoadTask::WonkoIndexRemoteLoadTask(WonkoIndex *index, QObject *parent)
+	: BaseWonkoEntityRemoteLoadTask(index, parent)
+{
+}
+QUrl WonkoIndexRemoteLoadTask::url() const
+{
+	return Wonko::indexUrl();
+}
+QString WonkoIndexRemoteLoadTask::name() const
+{
+	return tr("Wonko Index");
+}
+void WonkoIndexRemoteLoadTask::parse(const QJsonObject &obj) const
+{
+	WonkoFormat::parseIndex(obj, dynamic_cast<WonkoIndex *>(entity()));
+}
+
+//      WONKO VERSION LIST      //
+WonkoVersionListRemoteLoadTask::WonkoVersionListRemoteLoadTask(WonkoVersionList *list, QObject *parent)
+	: BaseWonkoEntityRemoteLoadTask(list, parent)
+{
+}
+QUrl WonkoVersionListRemoteLoadTask::url() const
+{
+	return Wonko::versionListUrl(list()->uid());
+}
+QString WonkoVersionListRemoteLoadTask::name() const
+{
+	return tr("Wonko Version List for %1").arg(list()->humanReadable());
+}
+void WonkoVersionListRemoteLoadTask::parse(const QJsonObject &obj) const
+{
+	WonkoFormat::parseVersionList(obj, list());
+}
+WonkoVersionList *WonkoVersionListRemoteLoadTask::list() const
+{
+	return dynamic_cast<WonkoVersionList *>(entity());
+}
+
+//      WONKO VERSION      //
+WonkoVersionRemoteLoadTask::WonkoVersionRemoteLoadTask(WonkoVersion *version, QObject *parent)
+	: BaseWonkoEntityRemoteLoadTask(version, parent)
+{
+}
+QUrl WonkoVersionRemoteLoadTask::url() const
+{
+	return Wonko::versionUrl(version()->uid(), version()->version());
+}
+QString WonkoVersionRemoteLoadTask::name() const
+{
+	return tr("Wonko Version for %1").arg(version()->name());
+}
+void WonkoVersionRemoteLoadTask::parse(const QJsonObject &obj) const
+{
+	WonkoFormat::parseVersion(obj, version());
+}
+WonkoVersion *WonkoVersionRemoteLoadTask::version() const
+{
+	return dynamic_cast<WonkoVersion *>(entity());
+}
diff --git a/libraries/logic/wonko/tasks/BaseWonkoEntityRemoteLoadTask.h b/libraries/logic/wonko/tasks/BaseWonkoEntityRemoteLoadTask.h
new file mode 100644
index 00000000..91ed6af0
--- /dev/null
+++ b/libraries/logic/wonko/tasks/BaseWonkoEntityRemoteLoadTask.h
@@ -0,0 +1,85 @@
+/* Copyright 2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "tasks/Task.h"
+#include <memory>
+
+class BaseWonkoEntity;
+class WonkoIndex;
+class WonkoVersionList;
+class WonkoVersion;
+
+class BaseWonkoEntityRemoteLoadTask : public Task
+{
+	Q_OBJECT
+public:
+	explicit BaseWonkoEntityRemoteLoadTask(BaseWonkoEntity *entity, QObject *parent = nullptr);
+
+protected:
+	virtual QUrl url() const = 0;
+	virtual QString name() const = 0;
+	virtual void parse(const QJsonObject &obj) const = 0;
+
+	BaseWonkoEntity *entity() const { return m_entity; }
+
+private slots:
+	void networkFinished();
+
+private:
+	void executeTask() override;
+
+	BaseWonkoEntity *m_entity;
+	std::shared_ptr<class CacheDownload> m_dl;
+};
+
+class WonkoIndexRemoteLoadTask : public BaseWonkoEntityRemoteLoadTask
+{
+	Q_OBJECT
+public:
+	explicit WonkoIndexRemoteLoadTask(WonkoIndex *index, QObject *parent = nullptr);
+
+private:
+	QUrl url() const override;
+	QString name() const override;
+	void parse(const QJsonObject &obj) const override;
+};
+class WonkoVersionListRemoteLoadTask : public BaseWonkoEntityRemoteLoadTask
+{
+	Q_OBJECT
+public:
+	explicit WonkoVersionListRemoteLoadTask(WonkoVersionList *list, QObject *parent = nullptr);
+
+private:
+	QUrl url() const override;
+	QString name() const override;
+	void parse(const QJsonObject &obj) const override;
+
+	WonkoVersionList *list() const;
+};
+class WonkoVersionRemoteLoadTask : public BaseWonkoEntityRemoteLoadTask
+{
+	Q_OBJECT
+public:
+	explicit WonkoVersionRemoteLoadTask(WonkoVersion *version, QObject *parent = nullptr);
+
+private:
+	QUrl url() const override;
+	QString name() const override;
+	void parse(const QJsonObject &obj) const override;
+
+	WonkoVersion *version() const;
+};