What is a UUID?
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit number used to uniquely identify something without a central authority assigning IDs. They're written as 36-character strings like 3f2504e0-4f89-41d3-9a0c-0305e82c3301. Version 4 UUIDs are generated from random numbers, making accidental collisions astronomically unlikely.
When to use UUIDs
- Database primary keys — unique IDs that don't reveal record counts or order
- Distributed systems — generate IDs on multiple machines without coordination
- API request IDs — trace requests across services
- File and session identifiers — unique names that won't clash
Secure and private
This generator uses your browser's crypto.randomUUID(), backed by a cryptographically secure random source. Every UUID is created locally and nothing is sent anywhere. Need secure passwords too? Try the password generator.