As explained in this answer software licenses that assert some form of copyright should include a year/author or they may not be recognized in the case of a future dispute.

Does the same thing apply to CC0? The CC0 FAQ recommends it, but doesn't require it and it isn't accompanied by a "Copyright ©" so it obviously isn't the same thing as in the answer linked above.

If it is required, does it have to be set in stone forever? So if I use my GitHub username and then change that username later (or change my contact e-mail) am I allowed to change it in the author note? Or does this void the license?

3 Answers 3


Since CC0 is essentially a way of waiving copyright, you don't need to add a "Copyright (C) ..." line. I generally replace that with a "written by Joe Blogs 201x" to allow subsequent users/distributors to keep track of the code's history but that is not required.

  • This only works in the US (and similar jurisdictions). In others (e.g. Germany) rights are attached to authorship, which cannot be transferred or abdicated, and a license is always needed for anyone else to use the work. This is why CC0 is necessary, otherwise it would be sufficient to declare that the work was placed in the public domain. Dec 17, 2021 at 7:57

The copyright and the license are two different things.

Placing (c)2017 Joe Blogs in a document is stating that you own the copyright of the work and are claiming the rights related to the copyright. If you don't openly display your copyright ownership then you may later need to offer proof that you created and published the work in any dispute and may even be asked to provide a compelling explanation as to why you didn't openly claim copyright at the time of publication.

As the owner of a copyright you have the ability to license the work to others. This gives you the power to choose and enforce the terms the work is licensed under.

As for usernames, "Joe Blogs" is the legal copyright owner. Authors can use pen names and have those names displayed in copyright notices so the same should apply to online usernames. Using an online name for copyright purposes could require further proof that you used that name at the time of publishing the work, which would need to include the old and new usernames to prove that both usernames were used by you.

While formal copyright registration has been voluntary for some time, it can be useful for some works such as art or photos to help prove ownership at a later time. For most works it is common practice to display (c)2017 Joe Blogs as a claim of copyright.

  • 3
    Well-written informative answer, but doesn't actually answer the question.
    – Wingblade
    Dec 11, 2017 at 13:21
  • 1
    While this answer discusses copyright notices, how does this explain their relation to CC0 dedications?
    – amon
    Dec 11, 2017 at 14:06
  • I would say adding (c) is always recommended but not required. By placing (c) in the file you are openly claiming the rights related to the copyright of the work, which includes the right to enforce licensing terms. That is the only relationship between the copyright and license. While cc0 is public domain, the copyright owner is still the only one with the ability to make the work freely available, by adding (c) you are claiming you have that ability.
    – sambler
    Dec 14, 2017 at 17:22

Here is what official wiki of CC0 creators says:

CC and the Free Software Foundation suggest that if you choose to apply CC0 to software, you include the following notice at the top of each file:



[other author/contributor lines as appropriate]

To the extent possible under law, the author(s) have dedicated all copyright and related and neighboring rights to this software to the public domain worldwide. This software is distributed without any warranty.

You should have received a copy of the CC0 Public Domain Dedication along with this software. If not, see http://creativecommons.org/publicdomain/zero/1.0/.

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.