Some users have added

Everything I post on Stack Overflow is licensed to you under CC0

to their profiles. I would like to know whether this is legal, because as far as I know stack exchange uses CC4.0, and I am not sure whether or not it is legal to add that to my Profile.

1 Answer 1


It's not illegal to say things in your profile. SE requires you to license your content to them on a non-exclusive basis pursuant to CC BY-SA 4.0. "Non-exclusive" means that you can also license the material to others on some other basis, e.g. CC0. In that case, a person who uses your material can rely on the other license that you granted.

If SE wanted to, it could prohibit putting licenses in a user profile, in which case you would have to promulgate your more generous license elsewhere.

  • However, CC0 is not (just) a license, it's intended as a public domain dedication. If I am in a jurisdiction where public domain dedications are accepted and publish an answer under CC0, I no longer have the authority to impose conditions as part of the CC-BY-SA license. In practice, I wouldn't expect this to be a problem though.
    – amon
    Jun 16, 2021 at 6:35

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