I'm making a web application that will generate revenue from displaying ads. The system is meant for me to run and not sold/distributed to anyone else.
My questions are:
- Can I use GPL licensed jQuery scripts on the website?
Yes, but see the third one.
- Can I use GPL licensed scripts while generating ad revenue from the page?
Yes. GPL doesn't say anything about generating revenue.
- Do I need to provide my sites source to everyone if I use GPL licensed scripts?
Excepted that the GPL gives you obligations only to people to whom you distribute and not everybody which could get an hand on the it and even less people who don't have access to the program, the matter is murky in my view. Ask a IP lawyer. At least two questions:
What is distribution for a web site? (See the discussions about the same question for embedded devices placed at user site but still the property of a service provider). I am not even sure that the fact that part of the site run on the browser and part on a server is pertinent.
What is the extend of the derived work? Just the script is for sure too small. The whole site can be arguably too large, at least in some cases. A set of sites could be pertinent in some cases (technical measure such as the deployment on one or several servers shouldn't be pertinent to the notion of derived work).
Can I use GPL licensed jQuery scripts on the website?
Absolutely.
Can I use GPL licensed scripts while generating ad revenue from the page?
Absolutely. The GPL has nothing to do with whether your website - or any application - is for profit or not.
Do I need to provide my sites source to everyone if I use GPL licensed scripts?
That's an extremely tricky one. If you have not modified the scripts themselves you don't need to provide any source. Whenever a user visits your site, they essentially download the full client side source code, that usually includes every bit of HTML, CSS and Javascript. Richard Stallman1, has indirectly acknowledged that behaviour as a valid sharing of GPL code, in his Javascript Trap article.
Javascript does not really have the "linking" concept, in the sense of "compiled against", and that's true for every interpreted language. Adding the fact that all your client side code is distributed by default, I think you are perfectly fine.
But if you are using any kind of minification/obfuscation on the scripts themselves, that might count as modification so you have to at least make sure that you preserve the original licence as it was and that there is a simple way of others to use the scripts, if they choose to. I have no idea what applies when the original author chooses to distribute the scripts in minified versions and you are using them instead of the full ones.
Now if you have modified the scripts themselves in any way, that's a different matter. You absolutely have to make sure that you distribute the modified scripts in a way that's compatible with the GPL - a way that makes it easy for others to use them if they choose to, and distribution via the browser doesn't count.
In that case, I'd probably share the modified source in a public repository, under a compatible license and link to the repository from my site. Think of something like a section in an "about" page that says something like:
This website is made possible by these fine open source projects:
Full source code of my modified version of the jQuery Horizontal Accordion plugin can be found here.
And a collection of smart little scripts I've build, available here.
The last part is not absolutely necessary, you can licence and distribute your own original scripts as you want - but since you already distribute their full source code it'd be nice if you released canonical (non minified/obfuscated) versions of them as open source.
Finally, jQuery core is dual licensed under the MIT Licence and the GPL. So in any case, if you are doing something incompatible with the GPL but compatible with MIT, you are fine. That's for jQuery core, not anything else that has jQuery in its name or is based upon it.
1 Bulgarian folk dance enthusiast and popular singer.
Disclaimer: Not a lawyer, treat all of the above as guesses. If you can afford it, consult with a lawyer.
