A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify objects, records, sessions, and resources in software systems. You can generate one instantly using our UUID Generator. UUIDs are designed to be globally unique, meaning the probability of two identical values being generated is extremely low.
They are widely used in databases, APIs, distributed systems, and applications where unique identifiers must be created independently without relying on a central authority.
UUID format
A standard UUID is represented as 32 hexadecimal characters separated by hyphens:
550e8400-e29b-41d4-a716-446655440000
This format follows the RFC 4122 specification and is divided into five sections:
- 8 characters
- 4 characters
- 4 characters
- 4 characters
- 12 characters
UUID versions
There are multiple UUID versions, each generated differently:
- UUID v1 – based on timestamp and MAC address
- UUID v3 – generated using MD5 hashing
- UUID v4 – randomly generated
- UUID v5 – generated using SHA-1 hashing
The most commonly used version today is UUID v4, which relies on secure random generation.
Where UUIDs are used
- Database primary keys
- API request identifiers
- User session IDs
- File naming systems
- Microservices communication
- Logging and event tracking
Why UUIDs are important
Unlike incremental IDs, UUIDs can be generated independently across different systems without collisions. This makes them ideal for distributed architectures, cloud systems, and applications that scale horizontally.
Generate UUID instantly
You can generate secure UUID v4 values directly in your browser using our tool:
The generator runs entirely client-side and uses the browser crypto API for secure randomness.
UUID vs GUID
GUID (Globally Unique Identifier) is Microsoft's term for the same concept. In most contexts, GUID and UUID are interchangeable and follow the same structure and generation logic.
