The Unlicense is a public domain dedication that also comes with a lax fallback license for places where the dedication may not hold. The GNU project says both the dedication and the fallback license are compatible with the GPL. In a policy, treat it as permissive, with a note on how to record it.
What the Unlicense does
The GNU license list describes it as a dedication to the public domain to the fullest extent permitted by law, plus an additional lax license that helps cover cases where the dedication is inadequate. That second part exists because the public domain is not a uniform concept across countries, and an author cannot always give up rights completely.
Recording it correctly
- Use the SPDX id Unlicense for components that carry this text, rather than writing public domain in a free text field.
- For code described only as public domain, with no license text, there is no standard id. Use a custom name and link to where the statement appears, and record it as something reviewed by a person.
- Use NOASSERTION only when you have not determined it. See NOASSERTION versus NONE.
Policy treatment
Unlicense and similar dedications generally land in the allow list next to MIT, BSD and Apache. A few points to check before you add them:
- Is the dedication the author's own, or does the repo only claim it? A third party cannot dedicate someone else's code.
- Does the project bundle other code under other licenses? The label on the repo does not describe vendored files.
- Does your legal team want a review for jurisdictions where the dedication might be questioned?
Copy and paste code
Snippets labelled public domain on forums and blogs are the riskiest case, since the poster may not hold the rights. Track where non trivial copied code came from, and prefer a library with a clear license over a pasted block.
What to ask a supplier
If a supplier's SBOM lists a package as public domain, ask for the source of that statement, not only the label.
Safeguard's SBOM and dependency scanning inventory your packages, and you can try the free scan. Whether a dedication is valid in a given country is for counsel.
Quick check
Is the Unlicense compatible with the GPL?
According to the GNU license list, yes, for both the dedication and the fallback license.
Is an unlabelled public domain claim enough?
Not on its own. Record where the claim comes from and whether the author actually holds the rights.
Sources
This post is general information, not legal advice.
Last reviewed: 19 October 2026.
