I want to make an online management tool for a server software using GPL licensed software. For the tool I'm fine releasing all software to anyone how wants it. After all, it's not rocket science.

The question I have arises when the tool can be used to write code and applications also using the GPL licensed software. The tool is not producing or generating any of the output. That is handled by the server software.

Two ways to get it:

  1. The client buys the software including the server software, installs it locally getting the GPL offerings required for the tool.
  2. It's a SAAS and the client signs up online.

Can the client develop internal applications without them having to release the sources in these cases?

If not, what problems are there?

  • 1
    This question is only vaguely related, but might give you a better understanding of how the GPL works with remotely used software components: programmers.stackexchange.com/questions/269316/…
    – Philipp
    Jan 9, 2015 at 9:41
  • 1
    see also: Licensing of content created by licensed code: "The GPL describes rules about the use of the source code, not rules about the use of products of the application itself. The most obvious example is the GNU compiler. The compiler is released under the GPL. It is perfectly fine to use that to compile programs that are not released under the GPL..."
    – gnat
    Apr 14, 2016 at 14:48

2 Answers 2


This question is handled in the GNU GPL FAQ:

Can I use GPL-covered editors such as GNU Emacs to develop non-free programs? Can I use GPL-covered tools such as GCC to compile them?

Yes, because the copyright on the editors and tools does not cover the code you write. Using them does not place any restrictions, legally, on the license you use for your code.

Some programs copy parts of themselves into the output for technical reasons—for example, Bison copies a standard parser program into its output file. In such cases, the copied text in the output is covered by the same license that covers it in the source code. Meanwhile, the part of the output which is derived from the program's input inherits the copyright status of the input.

As it happens, Bison can also be used to develop non-free programs. This is because we decided to explicitly permit the use of the Bison standard parser program in Bison output files without restriction. We made the decision because there were other tools comparable to Bison which already permitted use for non-free programs.

In what cases is the output of a GPL program covered by the GPL too?

Only when the program copies part of itself into the output.


I am not a lawyer. You should get one, if you are concerned about possible legal issues.

If your “tool is not producing or generating any of the output” there is absolutely no reason to worry about possible extending of GNU GPL’s copyleft to user’s data.

Even if it would do, that would not be a great problem, you would just have to take certain precautions, similar to that GNU Project took in the case with GNU Bison.

  • What about server function to store and retrieve the code? Can that be considered part of the GPL licensed application too?
    – Asken
    Jan 9, 2015 at 8:35
  • @Asken What about server fuctions? In the question you’ve said nothing about their licensing terms. If you are worrying about extending of copyleft via client-server protocol – no, that’s nonsense. Jan 9, 2015 at 8:40

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