Which license for open source but prohibiting commercial usage


(Undflybir) #1

I would like to change the license of my Firefox extension - currently it’s under MPL2
The source code and usage of the extension should still be free and open source, source code can be copied and modified - but with the following restrictions:

Published versions (changed or unchanged) must include a reference to the origin of the code (my extension source code)
Commercial usage is prohibited

Is there a fitting license I can use? Or do I have to write a custom one (which extends i.e. MPL2)?

And do I have to add the license to every published version of the extension, and would the new license be with retroactive effect?


(Niklas Gollenstede) #2

As far as I understaind the matter, this is a pretty good answer of the general question “How to open-source except for commercial use?”:

https://www.quora.com/What-is-the-best-free-for-non-commercial-use-license-to-use-for-an-open-source-project

Published versions (changed or unchanged) must include a reference to the origin of the code (my extension source code)

That sounds like attribution, which most open source licenses require.

Commercial usage is prohibited

I am pretty sure that if you want to prohibit the usage of the packed extension (no matter by whom), you’d not even be allowed to publish on AMO.

write a custom one (which extends i.e. MPL2)?

Don’t. If you have any interest that your project is forked and extended, use a common license. Otherwise, there is just too much that could legally go wrong and nobody will fork (neither you nor the people forking are lawyers).
If you are not interested in fork (which may later contribute to your own extension), just don’t open source your code. You are encuraged, but not required to do it.

And do I have to add the license to every published version of the extension

No. But unless you do, the published version is simply not published under that license (even though the code in say your GutHub repo is).

and would the new license be with retroactive effect?

Nope. If somebody grabs the current version of your code, at any point in the future, they can use it under the current license, pretty much no matter what you do now or later.
Since that old code is still your intellectual property (licensing doesn’t change that), you can always publish under additional* licenses, but you can’t revoke grands you already made (unless that was stated in the license, but open source licenses don’t do that (by definition, I think)).


Disclaimer: The above is my personal understanding of the matter, not legal advice. I am not a lawyer.


(Undflybir) #3

Many Thanks for your detailed answer!
My main concern was: people monetizing the source code. Because, all the work I put into its development was meant as a free service for the community


(Niklas Gollenstede) #4

main concern was: people monetizing the source code. Because, all the work I put into its development was meant as a free service for the community

That is a common concern. The way many licenses deal with it is pretty much:

You may use this code, but if you do, you have to open source your code as well.

Monetizing open source code is possible, but just grabbing someone else’s code and selling it, while allowed, is not really a business model. Why would people by it, if the same thing is available for free?