UUID v7 Generator
Generate time-ordered UUIDs (v7). They sort chronologically, which keeps database indexes from fragmenting the way v4 does.
UUID v7
Choosing a UUID version
- v1 — time plus a node id. Sorts by time in principle, but its byte order means it does not sort lexicographically. Historically leaked the machine MAC address; this tool uses a random node id instead.
- v3 / v5 — derived from a namespace and a name. Deterministic, so the same input always gives the same id. v5 (SHA-1) is preferred over v3 (MD5).
- v4 — pure randomness. The default choice when you just need a unique id.
- v6 — v1 with the timestamp reordered so it sorts correctly.
- v7 — Unix milliseconds plus randomness. The best choice for database keys.
Frequently asked questions
Which version should I use by default?
v4 for general identifiers, v7 when the value will be a database primary key or needs to sort by creation time.
Does the UUID format itself vary?
No. Every version is 128 bits written as 32 hex characters in 8-4-4-4-12 groups; only the meaning of the bits differs.
Related tools
UUID v4 GeneratorGenerate random UUIDs (v4) in bulk, using the browser’s cryptographic random source — never Math.random.ULID GeneratorGenerate ULIDs: 26 Crockford Base32 characters, sortable by time and safe to read aloud or type by hand.UUID v1 GeneratorGenerate time-based UUIDs (v1) with a random node id, so no MAC address is leaked.