This is a long due post, in response to a thread about a new JS outliner released under the GPL. I just did not take the time to write something about it until now… sorry!

It’s quite outstanding, but trying to find some good resource online about this issue is nearly impossible. If you try to read about how the GNU GPL impacts javascript web apps, you will find so much nonsense–that will make you believe the GPL is going to “infect” everything. (In spite of the fact that some of the most important Javascript libraries out there are licensed under the GPL, like Jquery IIRC.)

First, let’s get things straight: the GNU GPL does not infect anything nor has any “viral” effect. You don’t catch the GPL like the flu. In order for GPL obligations to kick in and apply to you, you must either:

  1. distribute GPL-licensed Javascript files; or

  2. write something that is based on GPL-licensed Javascript files.

In the first case, it’s no surprises that if you download and distribute GPL-licensed software, you must respect the conditions of the GPL.

In the second case, it’s a little bit more difficult to grasp, because you need to understand what constitutes a work based on the GPL program. And for this, you need an basic understanding of copyright law.

If you build other Javascript parts which will work with the GPL Javascript, there’s a fair chance that the whole is based on the GPL Javascript and thus is subject to the conditions of the GPL. (That’s the intended effect: it’s copyleft!) So for instance, if you write Javascript in which you re-use the functions of the GPL JS library, that will be covered by the GPL as well.

But for pretty much everything else, it’s not covered. So basically, just adding a line of script to interact with the DOM is not going to make the entire website subject to the GPL. That would be like saying using LibreOffice forces you to distribute all documents produced with it under the GPL. It’s just nonsense. Keep in mind that this is a legal thing, this is copyright law; this is not software development.

So in the case of the Concord outliner it’s pretty obvious: if you put an outliner in your web app, it’s not going to make the whole web app covered by the GPL. However, if you integrate the outliner and that you build your web app on top of that outliner; you expand it, so yes, that’s covered. But hey, that’s what the GPL is for.

Otherwise, write your own software from scratch or try a program with an alternative license, like the MPL-2.0.


No, I meant that if the GPL program does not suit you, then write your own program (NOT write your own license!). I agree in all cases it’s a bad idea to write your own license from scratch.

I will modify the sentence to reflect this better.


Comment by hugo