UUID generator

How UUIDs are generated

A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal digits in the pattern xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx, where M is the version and N is the variant. This tool generates version 4 UUIDs using the browser's crypto.randomUUID() API, which uses a cryptographically secure pseudorandom number generator (CSPRNG).

UUID v4 has 122 bits of randomness (6 bits are fixed for version and variant markers). The probability of two randomly generated UUIDs colliding is astronomically small: you would need to generate approximately 2.7 × 10¹⁸ UUIDs before reaching a 50% chance of a single collision. In practice, UUIDs are safe to treat as globally unique without any central coordination. They are widely used as primary keys in databases, filenames, session tokens, idempotency keys, and anywhere a unique identifier is needed without a central authority to issue sequential IDs.