Generate random version 4 UUIDs (also called GUIDs) instantly. Everything runs in your browser using a secure random source.
A UUID is a 128-bit identifier written as 32 hexadecimal digits in the pattern xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The 4 marks version 4 (random) and y is one of 8, 9, a or b. Databases, APIs and distributed systems use UUIDs as keys because any machine can create one without asking a central server, and the chance of two matching is vanishingly small.
Each UUID is built from 16 random bytes from crypto.getRandomValues. The version and variant bits are then set as described in RFC 4122, which leaves 122 random bits. That gives about 5.3 x 1036 possible values. Nothing is sent to a server, and nothing is stored.
A UUID (universally unique identifier) is a 128-bit label written as 32 hexadecimal digits in five groups, such as 123e4567-e89b-42d3-a456-426614174000. It lets separate systems create identifiers without coordinating with each other.
Yes, for practical purposes. GUID (globally unique identifier) is the name Microsoft uses for the same 128-bit format.
In theory yes, in practice no. A version 4 UUID has 122 random bits, about 5.3 x 1036 possible values, so the chance of a collision among even billions of identifiers is negligible.
The first digit of the third group is the version. A 4 means the UUID was generated from random numbers. The first digit of the fourth group is 8, 9, a or b, which marks the standard RFC 4122 variant.
They are generated with your browser's cryptographic random source, so they are unpredictable, but a UUID is meant to be an identifier, not a password or API key. Use the password generator for secrets.
See also: password generator · random number generator · Base64 encoder · timestamp converter · JSON formatter