What is UUID?
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information without a central authority. It is usually written as 32 hexadecimal digits in five groups, e.g. 550e8400-e29b-41d4-a716-446655440000.
Version 4 UUIDs are random and the most common; version 1 is time-based. Collisions are astronomically unlikely, which makes UUIDs ideal for database keys and distributed systems.
Key points
- A UUID is 128 bits, written as 32 hex digits in five hyphen-separated groups.
- Version 4 is random; version 1 is based on time and a node identifier.
- Collisions are astronomically unlikely, so no central coordinator is needed.
- They are larger than integer IDs and are not naturally sortable.
Example
550e8400-e29b-41d4-a716-446655440000
Common uses
- Primary keys in distributed databases
- Idempotency keys for API requests
- Correlation IDs for tracing requests across services
- Unique file or object names
Work with UUID directly in your browser.
Open the UUID Generator