If I get some code off of the public domain, and I make major changes, can I re-license it and put my copyright on it?

1 Answer 1


Yes. If something is truly public domain, then there is no copyright it at all. Note that only your changes are under the new copyright, not the original public domain code.

However, it sounds like you might have found code that is posted with no license. If this occurs, technically the default copyright is "all rights reserved". In that case you should ask the author to specify a license. I actually had to do this earlier today.

An additional caveat: since any source code you find is probably less than 70 years old, you should still ask the author to use a public domain equivalent license, because there are some weird legal issues in Europe.

  • Like, if I remove eveything but about 10 lines in a 100 line page?
    – Nate
    May 27, 2020 at 13:21
  • 1
    Public domain just means do whatever you want. You can use public domain material to create a new copyrightable work. Technically, you can even claim copyright on the public domain work itself, but that claim would be unenforcable.
    – Max Xiong
    May 27, 2020 at 14:16
  • So by unenforceable you mean that if the writer of the original could sue me for using it?
    – Nate
    May 27, 2020 at 14:51
  • @Nate That would be an example of a claim being enforced, not a claim being unenforceable. May 10, 2023 at 18:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.