Mozilla Public License (MPL)

The MPL is a detailed licence developed by the Mozilla Foundation. It is approved by both the FSF and the OSI. But MPL version 1.1 is not compatible with GPL. MPL version 2 is also not compatible with GPL under certain circumstances. Thus, developing a project involving both GPL licensed components and MPL licensed components is a difficult task. MPL is somewhat relaxed when compared with many other copyleft and permissive licences. Thus, software licensed under MPL can be widely used by proprietary developers. Examples of projects using MPL include Mozilla Firefox and Mozilla Thunderbird.