I have an application that I want to be MIT and I have a roo gem in my Gemfile (roo is licensed under MIT) however it depends on spreadsheet that has GNU license. Am I allowed to use roo and have MIT licence?

  • 2
    Can you be more specific with your question? Otherwise, the answer is "because those were the licenses the license holders decided to choose." May 30, 2016 at 19:02
  • Did my best =) I apollogise is this is still confusing May 30, 2016 at 19:06
  • Are you saying that roo depends on a GPL spreadsheet, or your application? It's unclear from your question.
    – David Arno
    May 30, 2016 at 20:57
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    The short answer is this: so long as you don't close the source, the MIT license is compatible with the GPL. See the FSF site for more information. May 31, 2016 at 6:16
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    This question suggests that @RobertHarvey's comment isn't correct. Whilst MIT is compatible with the GPL, your overall application must be GPL'ed if you use any GPL libraries within it. So whilst roo can be MIT-licensed, your app can't be as roo depends on a GPL-licensed component.
    – David Arno
    May 31, 2016 at 13:02

1 Answer 1


The MIT license is compatible with the GNU GPL. You can use MIT libraries in your projects, so long as you continue to abide by the GPL's terms.

However, the MIT terms only apply to the MIT library in isolation. If, for example, you want to close your source, you cannot do it if you use any GPL'd code in your project. The copyleft provision of the GPL takes precedence over the "use it however you like" terms of MIT.

So even though you're using MIT code that is compatible with the GPL, you still must abide by the responsibilities of the GPL.

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