Yes
Both zlib License and The Unlicense are permissive licenses with minimal obligations. Combining code under them is straightforward; ensure the original copyright notices are preserved alongside any new ones.
| License | Family | Patent grant |
|---|---|---|
| zlib License (Zlib) | permissive | No (implicit at most) |
| The Unlicense (Unlicense) | permissive | No (implicit at most) |
zlib License: Permissive, with a misrepresentation-of-origin clause.
The Unlicense: Public-domain dedication with a fallback license for jurisdictions that don't recognise PD.
If you found this page because you're trying to figure out whether shipping a particular dependency is safe, the answer above is a starting point — not a substitute for reading the actual licenses or talking to a lawyer when stakes are high.
LicenseHound walks every transitive dependency in your repo, maps each to its SPDX license, and flags pairs like this one in PR comments. The CLI is free; the team dashboard is paid.