License Clarification

[TruePath]

I notice your code has two licenses in the repository and since one of them releases the code into the public domain while the other is the GPL I was a bit confused. Are you releasing the code under both licenses?

I'm asking, because I was interested in creating a patch to zotero to improve djvu support and I wanted to first check the licenses were compatible and it's not completely clear when and what versions of the GPL are compatible with the AGPLv3. If you are also releasing it under the unlicense no problem.

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Though as a matter of curiosity why wouldn't you just release it under the unlicense given that it allows people to do everything the gpl allows and more?

[RussCoder]

Hello!

No, I don't release it under both licenses. The library is under GPL v2, everything else is under the Unlicense.

It's written in the LICENSE file.

GPL v2 code cannot be released under the Unlicense. Because GPL v2 requires everyone who uses the code in other apps, release those apps under GPL v2 or a stricter license. But the Unlicense puts no limitations on how one can use the code. In other words, GPL v2 is a copyleft license, while the Unlicense is a permissive license.

Initially, I published everything under the Unlicense, but later it occurred to me, that I copied certain pieces of code from DjVuLibre to my library, which makes my library a derivative work of DjVuLibre (which is published under GPL v2). So, I have to use the same license for the library. But for the viewer I still can use the Unlicense.

Some people are afraid of GPL v2 and say that libs under this license cannot be used on the web - because the whole website must be published under GPL v2. But it's not true, if you use the library as a separate script and don't bundle it with your code. The DjVu.js library is a separate JS file, which should not be bundled into an app, and should be added separately to the page (it is so due to technical reasons, namely, the initialization of Web Workers, but it turns out that it prevents one from violating GPL v2 as well :))

P.S.: Sorry for the late reply.