/uuid

UUIDs

Generate v4 (random) and v7 (time-sortable) UUIDs entirely in this tab.

Version Count

v7 UUIDs embed a millisecond timestamp; sorting them sorts by creation time.

How it works

What this is: A UUID is a 128-bit identifier, typically written as 32 hex digits split by hyphens (xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx). It's random enough that you can generate one anywhere in the world and trust it won't collide with anyone else's.
How it works: v4 uses crypto.getRandomValues for 122 bits of randomness and sets fixed version and variant bits. v7 (2024) encodes a millisecond-precision Unix timestamp in the first 48 bits, so sorting v7s is the same as sorting by creation time — handy for database indexes.
Worked example: v4: 7c9e6679-7425-40de-944b-e07fc1f90ae7 v7: 018f5e3a-7c19-7a4b-9c2d-3e8b1f2a4d5c ↑↑↑↑↑↑↑↑↑↑↑↑ timestamp prefix
Privacy: Runs entirely in your browser. No network requests. Nothing you paste or type leaves this tab.