I have an open source project on GitHub released under GPL3. I want to re-license it under GPL2. 99.9% of the program is written by me, only few lines of code is written by other people.

Can I re-license it again under GPL2? I mean, when someone sends me a pull request via GitHub, what is the "official agreement" between us on the issue?

  • 2
    If there are just a handful of lines by other people then the easiest thing to do is to explicitly ask them all for permission. Commented Jun 8, 2017 at 3:35

2 Answers 2


Since others have written code for the project, I believe they also have a small claim in the copyright of the project as a whole. Without a consensus of all copyright holders, I don't believe you are allowed to change the license of the project to GPLv2 because it is not compatible with GPLv3. However, if the other developers signed a contributor license agreement (see https://en.wikipedia.org/wiki/Contributor_License_Agreement and https://cla.github.com/), assigning the copyright to you, then you should be allowed to re-license.


When receiving contributions to a project, the default assumption is that the contribution is under the same licence as the project itself.

The main exceptions are when the contribution explicitly mentions a different licence or if it is of such a trivial/mechanical nature that the contribution doesn't qualify for copyright protection. The last reason will apply only very rarely.

As you have accepted contributions to your project, you don't own all the copyrights and you can't change the license without explicit permission from the other contributers to the project.

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