Mozilla Public License

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The Mozilla Public License ( MPL ) is an open source license from the Mozilla Foundation . Their main field of application is the licensing of the Mozilla - Web browser and related software . It has since been adapted for their software by others, B. from Sun Microsystems as a Common Development and Distribution License for OpenSolaris .

License terms

The Mozilla Public License is considered a "very weak copyleft " license and is sometimes viewed as a compromise between the GNU General Public License (GPL) and the BSD license , even if the MPL has restrictions that go beyond the two licenses. In principle, changed or copied source text files must remain under the MPL, but may be used together with proprietary code for a program. This means that a proprietary version of MPL open source programs can be published - for example Netscape Navigator version 6 or higher , which is a proprietary version of the corresponding Mozilla Suite or Mozilla Firefox . The MPL does not have a strong copyleft like the GPL.


The Mozilla Public License was originally developed by the Netscape company in 1998 for the code release of the then planned Netscape Communicator 5. Version 1.0 was drafted by Mitchell Baker while she was working as an attorney for Netscape. Then the Mozilla Foundation took over the further development and published version 1.1 a short time later. Version 2.0 was released on January 3, 2012.


In addition to many - in some cases significant - minor differences, the LGPL and the MPL differ in what counts as part of them and what is proprietary or an incompatible license. In the case of the LGPL, the LGPL code must continue to be independently closed and "functional" or compilable. With the MPL, it is only important that the source files are either individually under the MPL or not. This is a very weak condition because individual objects in particular can always have a different file. With MPL, the code can be so heavily integrated into proprietary code that it can hardly be separated from it.

Since the MPL is incompatible with the (L) GPL, especially in the opinion of the Free Software Foundation (FSF), Mozilla also provides its programs under the GNU Lesser General Public License and the GPL. Others followed this example, for example AOL, which also publishes the AOLserver under the GPL.

MPL and Debian

The MPL is DFSG compatible. Since the MPL 1.x stipulates that the source code must be available six months after distribution, this was, however, heatedly discussed within the Debian project. However, this function is guaranteed by, so this is not a problem.

In the past, Mozilla's logos were not free, so the versions distributed by Debian contained their own names and logos. In 2016, the bitmaps were placed under MPL 2 and the vector files under CC BY 3.0 . Therefore, the products were again sold with the names and logos of Mozilla.

Web links

Commons : Mozilla Public License  - collection of images, videos, and audio files

Individual evidence

  1. GNU Lesser General Public License - German translation of version 2.1 , §2
  2. Mozilla Relicensing FAQ
  3. Debian Wiki: The DFSG and Software Licenses , English
  4. Debian Legal Mailing List, Walter Landry: Re: MPL license , English