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How To Care If BSD, MIT, or GPL Licenses Are Used

The two recent posts about some individuals' choice of GPL versus others' preference for BSD and MIT style licensing has caused a lot of debate and response. I've seen everything as an interesting combination of very important topics being taken far too seriously and far too personally. All involved need to take a few steps back.

For the uninitiated and as a clarifier for the initiated, we're dealing with (basically) three categories of licensing when someone releases software (and/or its code):
  1. Closed Source. Easiest to explain, because you just get nothing.
  2. GPL. If you get the software, you get the source code, you get to change it, and anything you combine it with must be under the same terms.
  3. MIT and BSD. If you get the software, you might get the source code, you get to change it, and you have no obligations about anything else you combine it with.
The situation gets stickier when we look at those combinations and the transitions between them.

Use GPL code with Closed Source code

So long as you don't distribute your software this is fine. It is a perfectly OK thing to do for software running servers or only running in-house. However, if you want to distribute your software to end users, the terms of GPL code require that the GPL also applies to your own code, so you've got to give that code away, rather than keep it closed. Further, you have to let the users modify and redistribute it.

Returning modifications upstream?

Go ahead. As the owner of the closed source, if you decide to take portions that have modified the GPL code and return that to the project as a thank you, it is your right. You don't have to release your entire project's code to do this. Similarly, if you want to release other portions of your code for use, it is likely required to be GPL, itself.

Use MIT/BSD code with Closed Source code

This happens a lot, in the same kind of situation above, but also in distributed software, because that is OK. In some cases, a notice that you use the code is required, but you aren't required to put your own code under any particular rules or license.

Returning modifications upstream?

Just like GPL, this is fine. However, you have more freedom about releasing other components of your code under any license you see fit.

Use GPL code with MIT/BSD code

Oh, no! Now you have a problem, because the release of your own code under MIT and BSD style licensing is forbidden if you include or link it (the terms can be fuzzy with modern runtimes) with GPL code. You probably just can't use any GPL code if your own is MIT/BSD style.

Use MIT/BSD code with GPL code

Sure, go ahead. The GPL is fairly receptive. If you release an application under the GPL and it requires or includes MIT/BSD style licensed libraries, that is just fine.


If you're a closed source, server side or in-house project, you dont' have much to worry about. You aren't distributing, so little of this matters to you. If you're a closed source, distributed product, then GPL is off limits for you. As the lead of an open source project, you still need to worry about GPL code. Either it can limit how people can use your code, by forcing it to become GPL, or you could face limited use by making the decision yourself. In short, while its an acceptable license for its uses, it happens to be most limiting under these factors.

If you release some GPL code, I probably can't use it. Period. End of story (ignoring these commentaries about the story). Now, maybe you don't care if I can't use it, but isn't that why you're releasing it? The GPL is meant to protect us, but who and what does it protect us from? I can't release it in a closed source product, and I don't want to, but you're also keeping honest, open source enthusiastic developers from using your project. You aren't limiting us for technical or legal reasons, but only for our choice of another license. A GPL licensee can say anything about everyone having a freedom to choose their license, and this is true, but you can't escape your own choice specifically limits who else can interoperate based entirely on if they agree with you.


Florian said…
The choice of license is an act of personal believe and convictions.

You postulate that *GPL users are making a flawed moral choice by expecting others to agree with their convictions and that BSD/MIT users are above such flaw.

However, by suggesting that *GPL users agree with your convictions and switch to BSD/MIT, you invalidate any moral ground to make such a claim.

If you are truly committed to impose no choice on others, you may not, ever, make any suggestions that others (even when in fault) change their convictions to suit yours.
rgz said…
Oh no I have to call bu****it.

You can use all the the GPL you want in your distributed code, nothing is stopping you. You just have to change your license from MIT to GPL oh but you wouldn't do that!

You bash GPL users for their choice of license but you are unwilling to change license yourself, you are the one imposing the restriction, but why?

The GPL is meant to protect us, but who and what does it protect us from? I can't release it in a closed source product, and I don't want to, but you're also keeping honest, open source enthusiastic developers from using your project.

Oh no you don't, You want it to go closed source or at least keep it an option. Otherwise you wouldn't have a problem changing your license to GPL.

The the only reason to reject GPL'ed code you want use is because you can't take it into closed source projects.
Unknown said…
Do you know if I have a library or framework under the GPL license and someone builds a proprietary software(custom web site) for just 1 customer, and hands over the source code to this customer, can we say he is distributing the framework ? I mean in this situation do I have a right to ask him to publish the source for everyone or to buy a commercial license from me ?
Anonymous said…
@ivan: he's only required to provide the sourcecode to the customer. If you didn't buy, he's not required to (unless the license is AGPL or RPL, this changes the rules).
Anonymous said…

"The the only reason to reject GPL'ed code you want use is because you can't take it into closed source projects."

Yes, god, exactly. That's the whole freaking problem with GPL! I'm not sure what world you are living in, but most of my customers are not interested in giving the source code we right away to the public. Nobody wants to create competitors for themselves.

I'm glad that people out there are interested in writing high quality, free libraries for me to use (I don't really care of they are open source or not; it's the free part that I like). But forcing your software politics down peoples throat is bullshit and that's why GPL is bullshit. If you want to release your source code, go ahead. Forcing others to do it just for the privilege of using your library sucks.

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