Cairo is free software.

This (modified) version of the cairo implementation is available to be
redistributed and/or modified under the terms the Mozilla Public License
(MPL) version 2.0.  Some files in the original cairo source code are
available under more liberal terms, but we believe that in all cases,
each file may be used under the MPL 2.0.

Where the original code was not explicitly MPL licensed, the original
more liberal license information and copyright has been retained for
clarity of licensing and authorship.