We are thinking about to publish a module of a commercial closed software as open source under e.g. MIT or BSD.

The published open source module would have still some dependencies to the commercial closed software e.g. Interface, Superclass.

  • Can we publish the module as open source eg. MIT or BSD?
  • Can we host this module at GitHub?


1 Answer 1


You can publish your module if the proprietary software allows this.

In general, the source code of your module or plugin in itself is not derived from the proprietary program. So you hold the copyright for that program, and no one can tell you whether and how it may be published. As you are the copyright holder you may also publish on GitHub. There are two potential problems:

  • The license of the proprietary program may contractually prevent you from publishing the module.

  • Inheriting from proprietary classes or interfaces could make your code a derived work. Whether this is a case is a tricky question to which I don't know the answer.

The MIT and BSD licenses are both perfectly fine here. However, some licenses such as the GPL would require the whole system (proprietary software + your module) to be open source, so you wouldn't be able to use the GPL for your module – unless you provide a license exception. Compare the GPL FAQ. But these GPL-specific problems do not apply here.

  • The proprietary software allows this. It is our software based by our proprietary license, which has no restriction.
    – S6N9
    Sep 7, 2018 at 8:23
  • Publish on GitHub was only an option. Maybe it is better to host the open source module on our server and use MIT. thanks!
    – S6N9
    Sep 7, 2018 at 8:30
  • @S6N9 ok, this answer was written under the assumption you would be creating a module for a software that you licensed from someone else. If you own the software those considerations do not apply, and you can basically do whatever you want. The result is the same: you can publish the module as free software under whatever open source license you wish, as long as you don't use a copyleft license like the GPL that could also apply to your main product. If you publish, I strongly recommend creating a repository on GitHub for maximum visibility, issue tracking, and easy forking.
    – amon
    Sep 7, 2018 at 8:34

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