Last updated 23 August 2026
What makes a UUID "unique"
A version-4 UUID packs 122 random bits into a 128-bit value. The odds of generating the same one twice are so small that it's treated as effectively impossible in practice — you'd need to generate billions per second for billions of years before a collision became likely. That's why UUIDs are the standard choice for database keys, session tokens and anything else that needs an identifier no other system will accidentally produce.
Common questions
What is a UUID?
A Universally Unique Identifier — a 128-bit value, usually written as 32 hex digits in five groups, designed so that generating one anywhere is astronomically unlikely to collide with one generated anywhere else.
Is this random enough for real use, like database keys?
Yes. It uses crypto.randomUUID(), the browser's built-in cryptographically secure random number generator — the same class of randomness used for encryption keys, and the standard way modern browsers generate version-4 UUIDs.
What's the difference between a UUID and a GUID?
They're the same idea under two names. GUID (Globally Unique Identifier) is Microsoft's term; UUID is the more general, cross-platform name defined in the RFC 4122 standard. The format this tool generates works as either.