70 votes
Accepted

How can I determine if two open source licenses are compatible with each other?

I always look at the schema drawn by David Wheeler: Essay: FLOSS licenses The arrows show which license you can use in the context of another license. For instance: you can use software distributed ...
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51 votes

Can I use my own GPL'ed code in my closed source program?

You can freely issue additional licenses to your own GPL software, without restriction. Licenses can either give an exclusive or non-exclusive right. For example, an employment contract will ...
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  • 33.2k
47 votes
Accepted

Can I modify an open source license to require that I be notified?

I cannot say whether this would be considered open source, but it would not be free software. Free software confers, amongst other things, the right to modify the software; the FSF refer to this as ...
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  • 37.8k
39 votes

Can there be a copyright on negative code?

For me, this exposes a weakness in the mental model many coders seem to have about the operation of copyright. Consider a pile of bricks, representing code contributions to a work. In one (...
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  • 37.8k
35 votes
Accepted

Which licenses give me a guarantee that a software I'm installing is completely open-source, free of closed-source dependencies or components?

No Open Source license does that. Even the GNU GPL license allows one program to interact with another non-free program via pipes, sockets, streams etc. While the licenses can't do this, there are ...
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33 votes

Which license can protect a software to be distribute without changes under a different name?

This license isn't going to do what you want it to, for two reasons: I get the code, I add one space to an error message. It's now a modified version, so I can distribute it. I get the code. "My ...
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29 votes
Accepted

Are software licenses version-specific?

Firstly, since you are the sole author you are (presumably) the sole rightsholder, so you aren't bound by the licence anyway. Secondly, licences don't inhere in software, they attach to software ...
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  • 37.8k
28 votes
Accepted

If I'm using a GPL 3 library in my project, can I license my project under MIT license?

No; incorporating or linking against GPL requires that your project-as-a-whole be distributed under GPL. But you can include MIT licensed parts (or another GPL-compatible license) in the project. Also,...
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  • 8,455
24 votes
Accepted

Which license can protect a software to be distribute without changes under a different name?

My colleague has posted an excellent explanation of why a licence that does exactly what you've asked for would be pointless. It would also be non-free, because the right to distribute both non-...
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  • 37.8k
23 votes
Accepted

How can I judge the "strength" of a licence?

Speaking about “strength” is a simplification. Recipients must comply with all the licenses of all the components that are part of the program, and you cannot choose a license that makes compliance ...
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  • 33.2k
20 votes

Using an unmodified GPL library in non-copyleft code

As a add-on answer to amend what @amon explained in his answer: That is the point of releasing a library under GPL: Any program which wants to make use of it also needs to be distributed under terms ...
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  • 8,270
19 votes
Accepted

Are CDDL and GPL really incompatible?

Be careful with the claims about the CDDL on the FSF website, they are wrong. Some years ago, Eben Moglen confirmed to me in a private mail that the claims about the CDDL on the FSF website are based ...
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  • 758
19 votes
Accepted

Can I "upgrade" the version of CC BY-SA from 3.0 to 4.0 in my modification?

The CC-BY-SA 3.0 license is “forward compatible” with later versions. In section 4(b): You may Distribute or Publicly Perform an Adaptation only under the terms of: (i) this License; (ii) a ...
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  • 33.2k
18 votes

Can I copy-paste a snippet from Stack Overflow into my GNU-GPL project?

Stack Overflow contributions (and all of Stack Exchange's too) are licensed under CC-BY-SA 3.0. That basically means that You are free to Share — copy and redistribute the material in any medium or ...
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18 votes
Accepted

Why is GPLv2 incompatible with GPLv3?

Both the GPLv2 and the GPLv3 have clauses that Require the combined product to adhere to the license terms of the license of the GPL licensed component. Require that no additional restrictions may ...
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  • 8,986
18 votes
Accepted

Remove BSD LICENSE file while importing code into GPL project

The short answer is no. You cannot remove a BSD license notice, otherwise you are no longer licensed per the BSD (many variants) that all share the essential requirement to retain the copyright and ...
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18 votes

Can I modify an open source license to require that I be notified?

Do not use non-standard opensource licenses The other answers are great, and show that what you want to do is probably not too far down an OSS route but here is a different viewpoint. There's a ...
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  • 289
18 votes

Which licenses give me a guarantee that a software I'm installing is completely open-source, free of closed-source dependencies or components?

Which licenses give me a guarantee that a software I'm installing is completely open-source, free of closed-source dependencies or components? Unfortunately, a license cannot do that. Here's the ...
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  • 421
17 votes

Can I release under AGPL a program that uses a GPL library?

Yes, you can use a GPL3 library [1] in an AGPL3 program [2]. You can also cut-and-paste GPL3 code into an AGPL3 program. Both the ordinary GNU GPL, version 3, and the GNU Affero GPL have text ...
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  • 1,675
15 votes
Accepted

Is there a reason to prefer the SimPL over the GPL? Does it carry the same legal weight?

It is unacknowledged by the FSF, but was approved by the OSI in 2007. There are two main problems with "custom licenses": ghettoization - where the custom license creates its own ghetto with code ...
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  • 8,645
15 votes
Accepted

Can I link a Apache 2.0 library into software under GPLv2?

(Here's my best guess. This is obviously a very hairy problem to work through, and I've tried my best to reduce the problem down to basic principles. However, I may gotten some of those basic ...
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  • 30.9k
14 votes
Accepted

What are the differences between GPL V2 and V3 licenses?

This question was already asked on Stackoverflow in 2008 (but closed as off-topic there). This is a copy of the answer by Will M: Here is a short list of some the major differences: ...
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  • 11.2k
14 votes

Why is GPLv2 incompatible with GPLv3?

The creators of GPL recommend licensing software under "version X of the License, or (at your option) any later version". If the GPLv2 licensed code has been licensed as per those instructions, then ...
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  • 2,839
14 votes
Accepted

Can I use CodeProject code in a GPL project?

CPOL is not an open source license according to the OSI definition. It has a clause which does not allow it to be used for any purpose as mandated by the GPL or MIT license: You agree not to use ...
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  • 11.2k
14 votes
Accepted

Pros and Cons of using MPL-2.0 license?

Am I allowed to distribute the project for money under this license? Yes. However, if you distribute/sell binaries, then you may not charge extra for the source code. And, as the MPL license is a ...
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14 votes

Can I use my own GPL'ed code in my closed source program?

IANAL/TINLA: Proceed at your own risk. Yes. According to the GPL FAQ, it states here two things: I would like to release a program I wrote under the GNU GPL, but I would like to use the same code in ...
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13 votes
Accepted

Including resources with ambiguous license for GPL application

Generally, the question of whether artwork forms a combined work with software that displays has been addressed in What do I need to share if I include CC-BY-SA artwork in my software?. If your art ...
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  • 30.9k
13 votes

Can I modify an open source license to require that I be notified?

Adding a requirement to notify you when a fork is being made renders a license non-free. The reasoning behind this is that the requirement discriminates against people that, for whatever reason, are ...
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13 votes

Can there be a copyright on negative code?

Not all changes are of sufficient novelty to constitute something copyrightable, whether they are additions or deletions. For a simple example, consider any old out of copyright song or hymn of five ...
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