About UUID v4

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects. Version 4 UUIDs are generated using random or pseudo-random numbers.

Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is random and y is one of 8, 9, a, or b. The probability of a collision is astronomically low — you'd need to generate over a billion UUIDs per second for ~100 years to have a 50% chance of a duplicate.

All UUIDs are generated using crypto.randomUUID() or the Web Crypto API — no data leaves your browser.