The GPL tries to guarantee that a piece of software, and all derivative versions of that software, will allow anybody to use, study, modify, and distribute the software however they choose.

I think that the first three parts -- being able to use the software however you want, study the source code however you want, and modify the software however you want -- are great, and I'd like to license my work under a copyleft license that will protect those freedoms.

However, the freedom to distribute the software however you want can be a problem. As discussed in posts here and here, this clause forces you to use a Kickstarter, Patreon, pay-what-you-want, or support-services business model, as selling the software itself is no longer profitable. Not every independent creator has the option of using these business models, so I don't want to force them to allow free distribution of their software if they don't want to.

My question is: what copyleft software licenses are there that mandate that a program, and all its derivatives, allow users to access source code, use, and modify the program however they want, but do not mandate that they be able to distribute it however they want?

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    I understand the motivation of forbidding distribution, but think it's bad for users in practice. It's often the case that there's not a single creator of a software, but multiple contributors. With copyleft, they'd all be licensees of each other. Thus, even they would be prevented from distributing freely. Another issue is what happens when the original developers cease development, or go into an unwanted direction. The four freedoms imply the freedom to fork, and this is super important for the long-term health of a project (e.g. see NodeJS or LibreOffice).
    – amon
    Jun 16, 2021 at 5:47
  • @amon Interesting perspective! Thanks for your input. A solution I was thinking about was the 'mod' model, like how most video games work -- mods can extend, alter, or disable the functionality of a video game, but you have to have the original game in order for them to work. But that raises its own obvious problems! It's an interesting thing to think about. Jun 16, 2021 at 16:14

2 Answers 2


There can be no such free licence, because the distribution of unmodified and modified copies are two of the four freedoms of free software (the OSI definition protects those rights similarly).

Assuming by copyleft you mean a licence that requires derivative works to be under the same licence, CC's BY-NC licence allows distribution "for NonCommercial purposes only", and therefore probably comes closest to what you've asked for. Some software is distributed under this licence, but being non-free, further discussion of it is off-topic here.

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    My apologies for not reading the community guidelines more closely. I didn't realize this site was only for libre software -- I thought what I was suggesting would still fall under 'open source.' My mistake! Non-commercial licenses are a good thing to look at, though. Where else would I take this question on Stack Exchange? It kinda seemed like this was the best place to get an answer. Jun 16, 2021 at 16:17

The GPL and other copyleft licenses allow further distribution (under the same terms), they can't force anybody to distribute any changes they do in-house (as I understand what the relevant copyright laws say). They are crafted to ensure the code is always distributed so the recipient can use, study and change it at will.

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