I have an Android Game I've written that I released under the MIT license. Recently, there have been several people who have downloaded the source of my application, added ads and uploaded it to the Google Play store.

While this irks me, there's nothing legally wrong with what they are doing since my project is licensed under the MIT license. In order to stop this however, I'd like to relicense my application under the GPL.

The entirety of the code in its current state was written by me (minus ~3 lines or so that can be easily removed), however, the app has been translated into a few different languages by users, who have added their translations through GitHub pull requests.

Two Questions:

  1. Is relicensing my project under the GPL an good way to stop people from reuploading it as proprietary software with ads?

  2. If I decide to relicense my project under the GPL, do I need to track down everybody who has modified the translation files and get their permission? I know that this is the case when it comes to the code, however I'm not sure how this works with non code assets.


Just like everyone can take your MIT-licensed software and make it proprietary without having to ask all of its authors for permission, you can take your MIT-licensed software and license it under the GPL without asking the contributors.

MIT-licensed software can be integrated/made into GPL-licensed software. The other way around is not possible.

The FSF curates a list of GPL-compatible licenses, which includes the two licenses often called "MIT license":

  • X11 license

    […] is a lax permissive non-copyleft free software license, compatible with the GNU GPL

  • Expat license

    […] is a lax, permissive non-copyleft free software license, compatible with the GNU GPL

If you change the license to the GPL, and make changes to the software so that it differs from the version that is (and always will be) licensed under MIT, no one may distribute this new version as proprietary software without asking all authors for permission.

Of course this doesn’t stop someone from including ads in the software, but they would have to follow the terms of the GPL when distributing it (i.e., providing the source code and licensing it under the GPL, too).

  • 1
    To expand on the other half of this question, in almost every case I have seen, translation files are considered part of the source for a given program. (If source is speech, speech can also be source). So in the example, you have given, you would likely also need to either get explicit permission to re-license the translation files or remove them from the project. (IANAL/IANYL) – xzilla Aug 6 '19 at 2:03
  • This does mean, for the OP, though that it would only be a very slight deterrent, and no solution. – mirabilos Aug 20 '19 at 13:55
  • 1
    @xzilla read the answer more carefully. MIT-licensed content can be used as part of a project which is licensed in its entirety under the GPL. The translation files can be reused in this way, and are therefore not an issue. – MadHatter Nov 13 '19 at 8:57

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