Suppose I create some software from scratch. I sell the software, but I also keep it open source under the MIT License. Someone forks my repository and makes some great improvements to my software. Can I then clone their repository, and sell the improved software without sharing any profits?


Depending on how they chose to provide their fork, yes.

The MIT license, which you chose to license your work under, doesn't prevent anyone downstream from changing the license, nor from changing the license of a derivative - unlike a copyleft license such as the GPL. They can essentially license their fork how they like.

If they relicense it under CC BY-NC, you're not allowed to sell it because of the NonCommercial clause in BY-NC. However, that's not a free license.

If they've relicensed it under a free license (of which there's a list on the FSF website), then by definition this allows you to redistribute their work and sell it on.

Keep in mind, however, that if they're providing the same package for free, you're not going to get many customers simply because it's cheaper elsewhere.

  • So they are allowed to take my work under the MIT License and apply a license of their choosing to it? – Evorlor Jul 19 '15 at 15:43
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    @Evorlor yes - MIT doesn't prevent that. A copyleft license would. – ArtOfCode Jul 19 '15 at 15:44
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    @Martijn Indeed, the CC website rather explicitly says something along the lines of "CC licenses are not intended for software, please don't use them for such, use one of these instead" – Schilcote Jul 20 '15 at 3:21
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    @ArtOfCode Try to think of it this way: If what you are proposing were indeed possible, what difference would there be between CC-BY or CC-BY-NC? Or even between CC-BY and putting absolutely no restriction on it. Someone who licensed you the work under CC-BY-NC never gave you the right to use it non-commercially. While relicensing is indeed allowed, you can only relicense to stricter terms, not weaker. – neo Jul 20 '15 at 8:33
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    This has turned into a prolonged argument, something that is discouraged. I think this comment thread merits its own question. I look forward to seeing well thought-out interpretations arguing either position. – Free Radical Jul 20 '15 at 8:38

Yes, provided they license their improvements under MIT or another free/libre license.

Please note that MIT (Expat) is a permissive license, so the fork may no longer be free/libre software - the improvements may even be proprietary (ARR) - in that case, the other party will be able to sell the improved version, but you will not have that option (but you can still sell the your original version).

If you use a Copyleft license (e.g. GPLv3) instead of MIT/Expat, they can't do this. Then any improvements to your program must be licensed under the same license.

However, if the improvements have a free/libre license, you're allowed to sell free software, even if you don't hold the full copyright (or any copyright).

Also see: http://www.gnu.org/philosophy/selling.en.html (while this is from the FSF, it also applies to permissive licenses such as MIT (Expat)).

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