I am currently creating something that has been inspired by another library. It is a complete rewrite on another platform - yet, has the same purpose and functionality and is written in the same language. As far as I understand it, this is still considered a derivative work.

The original piece is licensed under the Apache 2.0 license.

Which steps do I need to take now when publishing my source under the Apache 2.0 license? Do I have to maintain copyright notices? If so, it can't obviously be in the source files (which are all new and cannot be mapped to the original piece).

What do I have to do to be on the safe side? What do I have to include when I distribute the sources?


If you only copied ideas from the original library and no actual source code, then your library is not a derived work as far as copyrights are concerned.

Copyrights are about the actual source code, not about the ideas/concepts that are represented in that source code. To protect those ideas/concepts, you need to turn to other intellectual property laws, such as trademarks and patents.

So, if your library is really a full rewrite (no traces of the original can be found), then you can release your library under any license you want, because you own the copyrights to it.

To be nice, you could mention the original library (possibly with a link) in your documentation as being your inspiration.

  • Thanks so far, but what if some datastructures closely ressemble each other? Or the same domain terms are used in both the libraries albeit with different implementations and interfaces? What if the architecture is similar, albeit not the same? Is that still no derivative work?
    – Falcon
    May 12 '14 at 12:42
  • 2
    @Falcon: For copyright only the actual copying counts. Similarities in architecture and domain terms are no problem. Similarities in data structures could be an issue if it gives the appearance of code having been copied. Where the boundary exactly lies is open for interpretation and can best be answered by your copyright lawyer. May 12 '14 at 13:00

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