Mozilla Public License

Terms

The MPL defines rights as passing from "contributors", who create or modify source code, through an optional auxiliary distributor (itself a licensee), to the licensee. It grants liberal copyright and patent licenses allowing for free use, modification, distribution, and "exploit[ation]" of the work, but does not grant the licensee any rights to a contributor's trademarks. These rights will terminate if the licensee fails to comply with the license's terms and conditions, but a violating licensee who returns to compliance regains its rights, and even receiving written notice from a contributor will result in losing rights to that contributor's code only. A patent retaliation clause, similar to that of the Apache License, is included to protect an auxiliary distributor's further recipients against patent trolling. The contributors disclaim warranty and liability, but allow auxiliary distributors to offer such things on their own behalf.

In exchange for the rights granted by license, the licensee must meet certain responsibilities concerning the distribution of licensed source code. Covered source code files must remain under the MPL, and distributors "may not attempt to alter or restrict recipients' rights" to it. The MPL treats the source code file as the boundary between MPL-licensed and proprietary parts, meaning that all or none of the code in a given source file falls under the MPL. An executable consisting solely of MPL-covered files may be sublicensed, but the licensee must ensure access to or provide all the source code within it. Recipients can combine licensed source code with other files under a different, even proprietary license, thereby forming a "larger work" which can be distributed under any terms, but again the MPL-covered source files must be made freely available. This makes the MPL a compromise between the MIT or BSD licenses, which permit all derived works to be relicensed as proprietary, and the GPL, which requires the derived work as a whole to be licensed under the GPL. By allowing proprietary modules in derived projects while requiring core files to remain open source, the MPL is designed to motivate both businesses and the open-source community to help develop core software.{{cite journal

The one exception to covered source files remaining under the MPL occurs when code under version 2.0 or later is combined with separate code files under the GNU GPL, GNU Lesser GPL (LGPL), or Affero GPL (AGPL). In this case, the program as a whole will be under the chosen GNU license, but the MPL-covered files will be dual-licensed, so that recipients can choose to distribute them under that GNU License or the MPL. The initial author of MPL code may choose to opt out of this GPL compatibility by adding a notice to its source files.

It is explicitly granted that MPL-covered code may be distributed under the terms of the license version under which it was received or any later version. If code under version 1.0 or 1.1 is upgraded to version 2.0 by this mechanism, the 1.x-covered code must be marked with the aforementioned GPL-incompatible notice. The MPL can be modified to form a new license, provided that said license does not refer to Mozilla or Netscape.

History

Version 1.0 of the MPL was written by Mitchell Baker in 1998 while working as a lawyer at Netscape Communications Corporation.{{cite book |author-link=Lawrence Rosen (attorney) |url-access=registration |archive-url=https://website-archive.mozilla.org/www.mozilla.org/mpl/MPL/NPL/1.1/ |archive-date=27 August 2015 |access-date=16 August 2016

However, at the same time, Baker developed a second license similar to the NPL. It was called the Mozilla Public License after Netscape's project name for the new open-source codebase and although it was originally only intended for software that supplemented core modules covered by the NPL, it became more popular than the NPL and eventually earned approval from the Open Source Initiative.{{cite web |access-date=29 February 2012

Less than a year later, Baker and the Mozilla Organization made changes to the MPL, resulting in version 1.1, a minor update.{{cite web |archive-url = https://web.archive.org/web/20080628174020/http://www.mozilla.org/mozilla-at-one.html |archive-date = 28 June 2008 |access-date = 1 March 2012 |url-status = dead |archive-url = https://web.archive.org/web/20110105015147/http://www.mozilla.org/MPL/NPL-1.0M-FAQ.html |archive-date = 5 January 2011 |access-date = 1 March 2012 |url-status = dead

Both versions 1.0 and 1.1 are incompatible with the GPL, which led the Free Software Foundation to discourage using version 1.1. For these reasons, earlier versions of Firefox were released under multiple licenses: the MPL 1.1, GPL 2.0, and LGPL 2.1.{{cite web |archive-url=https://web.archive.org/web/20090505215642/http://www.mozilla.org/MPL/relicensing-faq.html |archive-date=May 5, 2009 |access-date=28 February 2012 |url-status=bot: unknown |access-date=16 August 2016

Notable users

• Apache Flex (Formerly known as Adobe Flex)
• Armadillo
• Boulder, software that runs the Let's Encrypt certificate authority
• Cairo
• Celtx
• Cemu
• Eigen
• H2 (DBMS)
• Internet Systems Consortium
• LibreOffice
• Mozilla Firefox
• OpenMRS
• OpenTofu
• Syncthing
• Servo
• Brave Browser
• MonetDB (marked as "Incompatible With Secondary Licenses")
• RabbitMQ
• VLC (iOS Version)
• ZeroMQ (since version 4.3.5)

Licenses based on pre-MPL 2.0

• AROS Public License 1.1 (based on MPL 1.1)
• Common Development and Distribution License
• Common Public Attribution License
• Erlang Public License 1.1 (modified MPL 1.0, where "disagreements are settled under Swedish law in English")
• Firebird's Initial Developer's Public License (based on MPL v1.1)
• Sun Public License
• Yahoo! Public License
• Openbravo's Public License (based on MPL 1.1)
• Netscape Public License 1.1 (based on MPL 1.1)

References

References

1. "SPDX License List".
2. "MPL 2.0 FAQ". Mozilla Foundation.
3. "Mozilla Foundation License Policy". Mozilla Foundation.
4. "Open Source Software: a legal guide".
5. "Adobe Flex FAQ: Licensing". Adobe Systems.
6. (24 January 2013). "The meaning of the 4.0".
7. "Licenses". LibreOffice.
8. "Historical Licensing Documents". Mozilla Foundation.
9. (December 19, 2011). "Mozilla Public License 2.0 (MPL-2.0) {{!}} Open Source Initiative".
10. "About MPL 2.0: Revision Process and Changes FAQ". Mozilla Foundation.
11. "Mozilla Public License (MPL) version 1.1". Free Software Foundation.
12. (October 19, 2021). "Boulder - an ACME CA".
13. "cairographics.org".
14. "Celtx - Policies".
15. "Cemu/LICENSE.txt at main · cemu-project/Cemu · GitHub".
16. "Eigen".
17. "License".
18. (December 8, 2015). "Kea to be released under Mozilla Public License 2.0 - Internet Systems Consortium".
19. "OpenMRS Licensing Moves to MPLv2 - OpenMRS".
20. (October 20, 2021). "syncthing/syncthing".
21. "servo/servo".
22. "brave/brave-browser".
23. "Mozilla Public License — RabbitMQ".
24. (2023-06-06). "ØMQ Licensing - zeromq".
25. "Erlang Programming Language".
26. "ERLANG PUBLIC LICENSE: Version 1.1".
27. "English translation of the Erlang Public License legal text".
28. "Initial Developer's Public License".
29. "Openbravo Public License".
30. "Netscape Public License (NPL), versions 1.0 and 1.1". Free Software Foundation.