UUID Generator - Free Online RFC 4122 v4 UUID Tool
UUID Generator
Cryptographically Random RFC 4122 v4 UUIDs
Understanding UUIDs
Primary Keys
UUIDs make excellent distributed database primary keys since they can be generated independently without a central coordinator.
Unique Identifiers
Use UUIDs for session tokens, request IDs, file names, or any place a globally unique value is needed.
Test Data
Generate batches of realistic-looking unique IDs for seeding test databases or fixtures.
Cryptographically Random
This tool uses the Web Crypto API's secure random number generator, not Math.random(), for genuine unpredictability.
What Is a UUID v4?
A UUID (Universally Unique Identifier) is a 128-bit value formatted as 32 hexadecimal digits split into five groups. Version 4 UUIDs are generated using random or pseudo-random numbers, with fixed bits marking the version and variant. The odds of two randomly generated v4 UUIDs colliding are astronomically small — practically zero for any real-world use case.
Key Takeaways
- RFC 4122 Compliant: Every generated UUID has the correct version (4) and variant bits set.
- Bulk Generation: Generate up to 1,000 UUIDs at once for seeding test data.
- Client-Side Only: All generation happens locally in your browser using the Web Crypto API.