About UUIDTest
What this is
A UUID validator, generator and decoder that runs in your browser. Nothing you paste is uploaded, and generated values never leave the page.
| Tool | What it does | Limits |
|---|---|---|
| Validate (home page) | Checks the 8-4-4-4-12 shape, a version digit of 1 to 8 and an RFC variant, and generates one random v4. | Rejects the nil UUID and non-RFC variants, since those do not match the pattern. |
| Bulk generator | Up to 1,000 v4 or v7 UUIDs from the browser's cryptographic random source. v7 values from one batch are strictly increasing. | v7 is strictly ordered within a batch only; two machines generating at once are ordered by time to the millisecond, not against each other. |
| Timestamp decoder | Reads version, variant and the embedded time of v1, v6 and v7; accepts braces, urn:uuid: and bare hex; recognises nil and max. | A version-1 time is whatever the generating host's clock said. |
What a UUID cannot tell you
- Whether it is unique. Uniqueness is statistical for random versions and depends on clock and node correctness for time-based ones.
- Whether it is secret. A UUID is an identifier, not a capability token.