What is a UUID?
A UUID (universally unique identifier) is a 128-bit value written as 36 characters, like 3f2504e0-4f89-41d3-9a0c-0305e82c3301. Version 4 UUIDs are generated from random data, giving roughly 5.3 × 10³⁶ possible values — collisions are so unlikely they're treated as impossible in practice.
Where UUIDs are used
Database primary keys, API request IDs, session tokens, file names, distributed systems where multiple machines create records without coordinating, and anywhere you need an ID that's unique without a central counter.
How this generator works
UUIDs are produced with the browser's crypto.randomUUID() function, which uses a cryptographically secure random source. Nothing is generated on or sent to a server.