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UUID Generator

A version 4 UUID is 122 random bits. This page uses crypto.randomUUID, or Math.random when that function is missing. Quantity is capped at 1000. Hyphens and letter case can change.

Generated 0 UUIDs

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Publisher notes · reviewed 10 September 2026

UUID versions are not interchangeable

This generator creates identifiers in the version the control selects, using the Web Crypto API where required. A UUID is unique with very high probability, not a secret and not a proof of identity.

v4 versus v7 in practice

Version 4 is random. Version 7 (where offered) is time-ordered random, which can help database index locality. Do not parse a v4 UUID as a timestamp. Do not use UUIDs as API keys: they are guessable in bulk if the generator is weak, and they are logged everywhere.

Collisions for v4 are negligible for normal app volumes. They are not a substitute for a uniqueness constraint in the database.

Worked examples

  • Format

    A canonical UUID is 8-4-4-4-12 hex digits. The variant bits live in the first character of the fourth group. If that character is not in the allowed set, the string is not a RFC 4122 UUID.

Limits of this page

  • Not a ULID/KSUID converter unless a separate mode exists on the page.

Sources