UUID Generator

A UUID, universally unique identifier, is a 128-bit value written as 32 hexadecimal digits in five groups, like 3b241101-e2bb-4255-8caf-4136c566a962. Systems create them independently, without a central counter, and can be confident they'll never clash, which makes them ideal as database keys, file names, request IDs and API resource IDs.

This generator creates random version 4 UUIDs or time-ordered version 7 UUIDs, up to 500 at a time, in the format you need. Randomness comes from your browser's cryptographic generator. The checker reads any UUID's version, variant and, for time-based versions, the moment it was created.

UUIDs are 128-bit identifiers defined in RFC 9562, which replaced RFC 4122 in 2024. Version 4 is 122 random bits; the chance of two ever colliding is negligible: you'd need to generate about 2.7 quintillion before a 50% chance of one duplicate.

Version 7 puts a millisecond Unix timestamp in the first 48 bits and fills the rest with random bits, so new IDs sort after old ones. That keeps database indexes compact, which is why many teams now prefer v7 for primary keys.