Firstly I am sorry I do not fully understand about licensing. Thus I want to ask here for my curiosity about licensing things.
Here is the case. I build a WordPress theme that using underscores.me as its starter theme. It has GPL v2 license. And then I build the theme using Twitter Bootstrap. It has Apache v2 license.
I have been searching about both licenses. I found that Apache v2 is only compatible with GPL v3, not GPL v2.
What license can put to my code? Apache? GPl? Or I just can not release it because of Apache v2 and GPL 2 are incompatible? Finally, does it matter whether or not I modify the code?
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There is no way to license software that is the result of combining components that have Apache v2 license with and components that have GPL v2 license that does not contradict the terms of at least one of the licenses, even if you do not modify any of the components in either package.
The Apache Licensing discussion on GPL compatibility indicates that if you use software that is licensed under Apache v2, you must license that portion of your software under Apache v2. However, if you have also included software licensed under GPL v2, then your software is considered to be a derivative work, and you must release the entire software under GPL v2. But, since the Apache v2 license says that the portions covered by the Apache license must be released under Apache v2, you do not have permission to release it under GPL.
This is from the discussion in the Gnu FAQ section on incompatible licenses that says:
Only the copyright holders for the program can legally release their
software under these terms. If you wrote the whole program yourself,
then assuming your employer or school does not claim the copyright,
you are the copyright holder—so you can authorize the exception. But
if you want to use parts of other GPL-covered programs by other
authors in your code, you cannot authorize the exception for them. You
have to get the approval of the copyright holders of those programs.
However, nothing is stopping you from creating a website using a mix of GPL and Apache components. Both licenses permit you to use the software for derivative works and you do not need to license software you create to yourself in order to use it. The limitations the license impose are on copy and redistribution and sublicensing.
There are some related questions (with good answers) on the programmers stack exchange that may shed some more light on the topic.
- The GPL License Mixing.
- Can a GPLv2 program rely on Apache-licensed libraries?
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From http://www.apache.org/licenses/GPL-compatibility.html
Apache 2 software can therefore be included in GPLv3 projects, because
the GPLv3 license accepts our software into GPLv3 works. However,
GPLv3 software cannot be included in Apache projects. The licenses are
incompatible in one direction only, and it is a result of ASF’s
licensing philosophy and the GPLv3 authors’ interpretation of
copyright law.
So you can use! if you release your software to GPL v3.
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