What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier that is unique across all devices and time. UUIDs are used in software development to uniquely identify objects without requiring a central authority.
UUID v4 Format
UUID v4 uses random or pseudo-random numbers. The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where x is any hexadecimal digit and y is one of 8, 9, a, or b. The 4 indicates the UUID version.
UUID Versions
- v1 — Based on timestamp and MAC address
- v3 — Name-based using MD5 hashing
- v4 — Randomly generated (this tool)
- v5 — Name-based using SHA-1 hashing
- v7 — Unix timestamp + random (newest, sortable)
Common Use Cases
- Database primary keys
- Session identifiers
- API request tracking
- Distributed system object IDs
- File naming for uniqueness
- Temporary tokens and nonces
Frequently Asked Questions
Can UUIDs collide?
Theoretically yes, but the probability is astronomically low. You would need to generate about 2.71 quintillion UUIDs to have a 50% chance of one collision.
Is this tool free?
Yes, completely free with no sign-up or usage limits. Generate as many UUIDs as you need.
Are the UUIDs truly random?
Yes. This tool uses the Web Crypto API (crypto.randomUUID() or crypto.getRandomValues()) which provides cryptographically secure random numbers.
Is my data private?
All UUIDs are generated entirely in your browser. Nothing is sent to any server.