I have a question regarding the "MPL" license. Is it possible to re-brand and distribute an MPL licensed open-source software for commercial purposes? I read that Debian has rebranded software in MPL, but couldn't get a clear picture. Any pointers would be helpful.

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    Why do you think it might not be legal to do this, and is this is particular concern about the MPL or about open source licenses in general? Jul 20, 2020 at 7:17
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    By "commercial purposes", do you mean "proprietary" or "money-making" (ie, not-free-as-in-speech or not-free-as-in-beer)?
    – MadHatter
    Jul 20, 2020 at 7:18
  • @MadHatter We are thinking of distributing this piece of software (rebranded) as part of our custom-developed application. But we may not charge for it other than rebranding,
    – kallada
    Jul 20, 2020 at 7:31
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    That answers for free-as-in-beer, though ambiguously. But on what licence terms do you intend to redistribute it?
    – MadHatter
    Jul 20, 2020 at 7:33
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    And finally, when you write "as part of our custom-developed application", do you intend to incorporate this MPL-covered source into the source of your application, or do you simply intend to distribute the MPL-covered software as a standalone application, packaged with your application?
    – MadHatter
    Jul 20, 2020 at 7:43

1 Answer 1


Rebranding a software suite is a modification that is allowed by all open-source licenses. If you can effectively use the rebranded software in your commercial product depends on the license terms and if they would conflict with the way you want to exploit the commercial product.

The MPL license has 3 main requirements that are relevant here

  • The source code must remain under the MPL license
  • Recipients of the binaries must be informed of their rights and where they can obtain a copy of the source code (at a cost no higher than the actual distribution costs)
  • The license on the binaries may not restrict the rights on the source code.

Regarding the rebranded MPL software in the Debian distribution, Debian has used rebranded versions of the Mozilla applications Firefox, Thunderbird and SeaMonkey from 2006 to 2016. The rebranding was done because Debian and Mozilla had a conflict over the terms for using the Mozilla trademarks (which includes the branding).

  • Thank you. If distribute the rebranded MPL-covered software as a standalone application, packaged with my application, will it affect the proprietary license of my software?
    – kallada
    Jul 20, 2020 at 10:25
  • @kallada, no. The MPL is a weakly copyleft license: there are no constraints on the license of code that gets combined with MPL code, for example through linking. Jul 20, 2020 at 11:53

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