Is it possible to fork a project (which I don't own) and change the license from BSD to for example LGPL / GPL / AGPL?
I read it would be possible to change fork's license to something compatible to BSD - is this just a rumor / urban legend?
3 Answers
You can license your new changes under a license compatible with the old license and relicense the entirety of the new project with the new license (as it is now a derivative work of the changes you have made under the GPL).
However the original code does not change its license. If the code is licensed under the BSD license, it is licensed under the BSD license. You may not change that. You may not remove the BSD license from the code that you received (forked).
Only the entity that controls the copyright for the code has the legal authority to change the license of the existing code to something else.
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"Only the entity that controls the copyright for the code has the legal authority to change the license of the existing code to something else." - Not quite true. The copyright owner may give away the intellectual property, which others are allowed to use and license as they see fit. But I would agree that they are changing the license for a derivative of the original creation.– user53019May 20, 2014 at 14:18
Is it possible to fork a project (which I don't own) and change the license from BSD to for example LGPL / GPL / AGPL?
It depends upon which BSD license is used.
The BSD 2-clause license is compatible with the GPL, but the BSD 3-clause license is not.
The FSF has declared the BSD 2-clause license to be compatible with the GPL. And by "compatible" they mean:
you can combine code released under the other license with code released under the GNU GPL in one larger program.
It's important to keep in mind that "compatible" is really just a euphemism for a re-licensing of the resulting project under the GPL.
The BSD 3-clause is not compatible with the GPL as explained here
Because it imposes a specific requirement that is not in the GPL; namely, the requirement on advertisements of the program. Section 6 of GPLv2 states:
You may not impose any further restrictions on the recipients' exercise of the rights granted herein. GPLv3 says something similar in section 10. The advertising clause provides just such a further restriction, and thus is GPL-incompatible.
To address the specifics of forking. The BSD 2-clause license states:
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
That first clause that I have emphasized means you are permitted to do what you want with the BSD licensed project. So you're free to fork the project.
Remember to keep the original copyright notices and disclaimer of liability in place in order to honor the terms of the BSD license. But other than that, you're free to do what you want.
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Perhaps you meant to say the BSD 4-clause license? The BSD 3-clause is compatible.– ZN13Jul 25, 2019 at 15:51
From wikipedia (http://en.wikipedia.org/wiki/Fork_(software_development)) "The BSD licenses permit forks to become proprietary software". Since "proprietary software" is more restrictive then other open source licenses, you should not have any problem: since the fork can be your "proprietary software", you can release with any license you like. (Btw, I'm not a lawer :P ).
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1BSD licensed software can become closed source software (which is often confused with proprietary software), because the license doesn't require you to redistribute sources along with (modified) binaries. This does not mean you can change the license when you do choose to redistribute the sources. May 20, 2014 at 14:05