Do I have to open-source my code if I use CC0-1.0?

No. CC0-1.0 never requires you to disclose your source.

Does running CC0-1.0 software as a SaaS require source disclosure?

No. Hosting is not distribution under CC0-1.0; running it as a service does not trigger source disclosure.

Is CC0-1.0 compatible with the GPL?

Yes — compatible with the GPL.

Creative Commons Zero 1.0 (CC0-1.0)

Public-domain dedication. FSF treats it as GPL-compatible; note it expressly does NOT grant patent rights, and OSI never approved it for that reason.

Key facts

SPDX id: CC0-1.0
Category: Public domain
Copyleft scope: none
Express patent grant: No
SaaS triggers disclosure: No
GPL-compatible: Yes — compatible with the GPL.

Obligations

When redistributing as open source.

CC0-1.0: No patent grant.

Commercial use

Yes. Commercial use is permitted; retain the copyright notice and license text.

CC0-1.0: No patent grant.

Permissive: include notices (Apache also needs NOTICE + change statements). Weak copyleft: disclose only the modified library/files and, for LGPL static linking, provide a relink path. Strong copyleft (GPL): NOT possible to keep proprietary if GPL code is in the derivative work. AGPL: same as GPL plus network rules.

FAQ

Can I use CC0-1.0 in a commercial product?: Yes. Commercial use is permitted; retain the copyright notice and license text.
Do I have to open-source my code if I use CC0-1.0?: No. CC0-1.0 never requires you to disclose your source.
Does running CC0-1.0 software as a SaaS require source disclosure?: No. Hosting is not distribution under CC0-1.0; running it as a service does not trigger source disclosure.
Is CC0-1.0 compatible with the GPL?: Yes — compatible with the GPL.

Compatibility with other licenses

Open the checker with CC0-1.0 selected