Is there a default license for Firefox add-ons?

Question

Do they have to be GPL or can they be something else? And if nothing is specified in the code are they considered to be GPL by default?

Answer 1

I'm not a lawyer, so take this with a grain of salt.

First off, Mozilla has nothing to do this. There is no reason to believe that Firefox add-ons are GPL-licensed by default. That's because the license of the browser doesn't affect the license of the add-ons; they don't typically reuse the browser's source code. (In fact, Firefox itself isn't necessarily GPL'd. Mozilla releases it under a tri-license which includes the Mozilla Public License as one of the license options.)

So, I'd imagine that if you don't specify a license to an add-on, then that add-on defaults to whatever copyright control would be extended to you as author of the add-on, depending on your jurisdiction.

Now if you used GPL'd code in your add-on, then that add-on would obviously be GPL-licensed if you released it publicly. Unless you got special permission from the original author to use a different license, of course.