UUID / GUID Generator
Generate RFC 4122 compliant UUIDs (v4) in bulk, instantly.
Random UUIDs, generated in your browser
A UUID (Universally Unique Identifier) is a 128-bit number represented as a string like 6fa459ea-ee8a-3ca4-894e-db77e160355e. They are the default choice when you need an identifier that does not collide, cannot be guessed, and does not require central coordination.
What’s in a UUID
A canonical UUID is written as 32 hexadecimal digits in five groups separated by hyphens: 8-4-4-4-12. RFC 4122 defines several versions:
- Version 1 embeds a timestamp and the generator’s MAC address.
- Version 4 is fully random (except for a handful of fixed bits that identify the version).
- Version 7 (newer) is time-ordered and ideal for database indexes.
This generator uses Version 4 — the most widely supported and the right default for most use cases.
When to reach for a UUID
- Distributed systems where multiple nodes create records without a central sequence generator.
- Offline-first apps that need IDs before the server round-trip.
- URL slugs where you want unguessable resources without auth middleware.
- Temporary tokens for single-use links (though signed tokens are better when verifiable).
Privacy
IDs are generated locally using crypto.randomUUID(). Nothing is logged; the identifiers you generate never leave the device.
Frequently asked questions
- What version of UUID is generated?
- Version 4 — the random UUID. Each identifier is generated using crypto.randomUUID(), which uses the browser's cryptographically secure random source. Version 4 UUIDs are the right default for almost every application.
- Are these UUIDs safe to use as primary keys?
- Yes, with caveats. A v4 UUID has 122 random bits, which makes collisions astronomically unlikely. They work well for distributed systems, but are larger and less cache-friendly than integer IDs. If sorting by creation time is important, consider UUID v7 (time-ordered).
- Can I generate IDs without hyphens?
- Yes. Toggle "Hyphens" off to produce 32-character compact IDs. Toggle "Uppercase" to get the hex digits A–F in uppercase.