A UUID — universally unique identifier — is a 128-bit value used to label information so that it is practically guaranteed never to collide with another, even across different systems and databases.
The shape of a UUID
A UUID looks like 550e8400-e29b-41d4-a716-446655440000: 32 hexadecimal digits in five groups separated by hyphens. Version 4 UUIDs are generated almost entirely from random numbers, which makes them easy to create anywhere without a central authority.
Why developers love them
UUIDs let distributed systems assign IDs independently without coordinating, which is vital for offline-first apps, microservices and database sharding. They also avoid leaking record counts the way sequential IDs can.
Generate UUIDs on demand
A UUID generator produces valid version 4 identifiers instantly. Generate one or many at a time, copy them, and drop them straight into your code, database seeds or test fixtures.