How to Use the UUID Generator
- Click Generate UUIDs to produce 8 cryptographically secure UUID v4 strings.
- Click the copy icon next to any UUID to copy it to your clipboard.
- Generate again for a fresh batch — all computation happens in your browser.
What is a UUID?
A UUID (Universally Unique Identifier) is a standardized 128-bit identifier used across software systems to uniquely label entities without requiring central coordination. The format is defined in RFC 4122:
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxxWhere x is a hexadecimal digit and y is one of 8, 9, a, or b (indicating v4 random). A complete example: f47ac10b-58cc-4372-a567-0e02b2c3d479.
Common Uses for UUIDs
UUIDs are essential across modern software development:
- Database primary keys — UUID columns in PostgreSQL, MySQL, MongoDB, and SQLite
- REST API resource identifiers —
/users/550e8400-e29b-41d4-a716-446655440000 - Session tokens and correlation IDs — tracking requests across distributed systems
- File naming — ensuring uploaded files never collide:
f47ac10b.jpg - Event sourcing — unique IDs for events in CQRS/event-driven architectures
UUID Collision Probability
UUID v4 uses 122 bits of randomness. The probability of generating a duplicate UUID is approximately 1 in 2^122 — roughly 5.3 × 10^36. In practical terms, you would need to generate about 2.71 quintillion UUIDs before having even a 50% chance of a collision. For any real-world application, collisions are not a concern.
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems. The standard format is 8-4-4-4-12 hexadecimal characters separated by hyphens, e.g. 550e8400-e29b-41d4-a716-446655440000.
What is UUID v4?
UUID v4 is randomly generated. It uses 122 bits of randomness, making the probability of collision astronomically low. It's the most commonly used UUID version for general-purpose identifiers.
Is this UUID generator cryptographically secure?
Yes. This generator uses the browser's built-in crypto.randomUUID() function, which is cryptographically secure and RFC 4122 compliant. No server is involved — generation happens entirely in your browser.
Can I use these UUIDs in production?
Yes. UUID v4 generated by crypto.randomUUID() is suitable for production use as primary keys, session tokens, correlation IDs, file names, and any other unique identifier requirement.
What's the difference between UUID and GUID?
GUID (Globally Unique Identifier) is Microsoft's term for UUID. They are the same format and standard — the terms are interchangeable.