GPL and hosted services [closed]

Question

As I understand it GPL says you only have to distribute derivative code for works you distribute, i.e. if you develop internal software you can keep your code private.

What happens if you develop a server application, say like Facebook or StackOverflow? The server app is not 'distributed' so what's the situation with your code in this case?

Clarification Imagine I make my own VCS based on CVS and I sell access as a service, but don't let other people run their own servers... like Codesion's business model. I'm making money from something heavily based on GPL code but I never release the server itself - does this mean I am not obligated to release the source under GPL?

BTW, discussion on the moral as well as legal side is welcome.

Answer 1

The GPL FAQ answers this question:

A company is running a modified version of a GPL'ed program on a web site. Does the GPL say they must release their modified sources?

The GPL permits anyone to make a modified version and use it without ever distributing it to others. What this company is doing is a special case of that. Therefore, the company does not have to release the modified sources. [...]

In contrast, the GNU Affero GPL closes this "ASP loophole" and requires release of the modified source even in that circumstance.

Answer 2

IANAL

It isn't entirely clear from your question whether you are asking about your obligations as someone who uses (a modified version of) some software licenced under the GPL, or as someone who has written software that is currently licenced under the GPL and you are concerned about what people who use your software are allowed to do. They're two complementary issues.

Under the simple GPL, you are not obliged to distribute modified versions of the source code when you do not distribute the modified program - and simply running the program, or allowing others to run it via a web service, does not constitute distributing the program. Similarly, those who obtain software from you that you have licenced under the GPL and who use it to supply information to their own customers (whether they've modified it or not) are not obliged to distribute the source code.

There is a variant of the GPL, recognized by the FSF, called the Affero GPL (AGPL), which may be appropriate for products which can be used to provide a web service. It requires that if you provide a service over the Internet using a product licensed with the AGPL, then you are obliged to distribute the (possibly modified) code after all. See the Open Source Initiative for more information.