Wappalyzer has recently been re-licensed to MIT; however, it was previously licensed under GPLv3.

I had opened an issue to clarify whether it was GPL-3.0-or-only, or GPL-3.0-or-later before this change, and I am not quite sure the developers realize the implications of this change.

Wouldn't this change violate the terms of the previous copy-left license?


  • 1
    See: gnu.org/licenses/license-list.en.html#Expat, it seems to fall in the GNU v3 compatible section. However, according to en.wikipedia.org/wiki/MIT_License "; MIT licensed software can be re-licensed as GPL software, and integrated with other GPL software, but not the other way around." Which seems problematic. I'll try to dig up some more details.
    – kingthorin
    Apr 8, 2020 at 20:14
  • That is what I read also. I will update the question to reflect this.
    – oxr463
    Apr 8, 2020 at 21:45
  • Why do you think there is any violation? The author of some code can suddenly decide to stop distributing the code via GPL and only offer a commercial license no problems. An author is not bound by the license. Authors have full rights to their works. The license is used to norm other people's rights.
    – Bakuriu
    Apr 9, 2020 at 6:34
  • 1
    @Bakuriu I'm not the OP, but I believe I can answer. While you're right that the author of some code can change the license under which they offer their own code at will, they cannot necessarily unilaterally change the license under which they offer other people's code. That's what the maintainer of Wappalyzer is trying to do here. Other people wrote some code and granted the maintainer the right to use (and distribute) that code under the GPLv3. Now the maintainer is distributing that code under the MIT license.
    – David Z
    Apr 9, 2020 at 8:25
  • 3
    @Bakuriu go take a look at the repository in question. 491 different contributors are listed, and the consent of every single one would be required to relicense from GPLv3 or GPLv3+ to MIT. I'm not saying the lead coder hasn't gained this consent, but I can as yet find no evidence of it on the repository.
    – MadHatter
    Apr 9, 2020 at 8:26

1 Answer 1


Wouldn't this change violate the terms of the previous copy-left license?

It is indeed true that the GPL itself does not give permission to offer another's work under more permissive terms like the MIT/X11 license.

Of course, nothing precludes a copyright holder from allowing their work to be made available under other terms besides the GPL. The relevant question is: does there exist any person who contributed their copyrightable work into the project under the GPL (and no other terms) and now objects to the distribution of their code under more permissive MIT/X11 terms? If so, that person could sue (or credibly threaten to sue) based on infringement of their copyright due to distribution under unauthorized terms.

This case would not be true if all contributors offered their contributions under more permissive terms, e.g., according to a contributor licensing agreement (CLA) that allowed the project owner to distribute their work under more permissive terms.

In the United States, there is an interesting legal concept of a "joint work" wherein all contributors of the work have full independent standing to distribute and offer licenses to the entire work. However, I am not sufficiently well versed in law to say when circumstances are sufficient to create joint ownership in a particular work.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.