I have developed a tool that uses another tool to convert a file from format#1 to format#2. And currently, my tool works only if it is given the file in format#2 as input, and so, it depends on that format#2. And to convert from format#1 to format#2, I modified converter tool and made those changes public as well through GitHub. The converter tool has Apache 2.0 License but when I had downloaded it, it had Lesser GPL license.

Now I want to make my tool open source. Can I use Affero GPL or LGPL or GPL license for my tool or should I stick to Apache License only?

  • Please try to write more descriptive titles. I edited your question and changed the title -- does this reflect what you want to ask? If not, please edit.
    – unor
    Oct 12 '16 at 0:49
  • I think, that was not my question at all. My question was for my own tool, not for tool#2. All the changes I made to tool#2 are already public and under Apache License anyway. Oct 12 '16 at 1:02
  • I see, but now your title is the almost the same not-very-descriptive one from before. Can you come up with a more descriptive one? Not sure I understand your case fully, but maybe: "… for my tool that interacts with an Apache 2.0 licensed converter"?
    – unor
    Oct 12 '16 at 3:10
  • Wait, your tool to convert to format#2 (from format#1) requires input to be in format#2 already!? I'm guessing this question should say: "my tool works only if it is given the file in format# 2 as input"? Oct 17 '16 at 10:43

The converter tool you modified

When you downloaded the tool it was under LGPL. So, normally you should have published your modifications under that license. But you say that it is now available under Apache 2.0. Are all versions of the tool now also licensed under this new license or is it just new versions? If it's just new versions, you should make sure that your modifications apply to a version whose code is currently released under Apache 2.0 before publishing your modified version under this license as well. Otherwise, you could have published them under the original LGPL license.

You should also quickly check that the license change seems legitimate. Typically, if the converter tool was the work of one single author, then it's probably legitimate. In other cases, that can be more complicated.

The converter tool you created

You can publish this one under any license you wish as it is your own work.

The combination of the two converter tools

This "whole work" can only be published under a license which its dependencies are compatible with. Whether the converter tool you modified should have been licensed under Apache or LGPL does not change much to the game because both of these licenses are compatible with AGPL 3.0 and GPL 3.0. So feel free to use one of these for the whole work.


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