UUID Generator (v4)
Generate cryptographically random version-4 UUIDs, one or in bulk, with one-click copy. Free online GUID generator.
About version-4 UUIDs
A UUID (also called GUID) is a 128-bit identifier designed to be unique without any central registry. Version 4 fills 122 of those bits with cryptographically secure randomness — the collision probability is so small that generating billions per second for decades still wouldn't produce a duplicate in practice. They're the default choice for database keys, request IDs and distributed systems.
This generator uses your browser's crypto.randomUUID() (with a secure fallback), so the values are generated locally and never transmitted.
Frequently asked questions
Are these UUIDs really unique?
Statistically yes — the random space is 2^122. No coordination is needed, which is exactly the point of UUIDs.
UUID vs GUID?
Same thing — GUID is Microsoft's name for UUIDs. The format and guarantees are identical.