UUID Generator

Generate cryptographically random version-4 UUIDs (GUIDs) — one or in bulk. Everything runs in your browser using the secure crypto API; nothing is sent anywhere or stored.

What is a version-4 UUID?

A version-4 UUID is 128 bits of (almost entirely) random data, formatted as xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where the 4 marks the version and y is one of 8, 9, a, b. Because the value is random and huge, two independently generated UUIDs practically never collide — which is why they are ideal as primary keys, request IDs, file names and idempotency keys in distributed systems.

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Frequently asked questions

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hex digits in five groups, e.g. 3f2504e0-4f89-41d3-9a0c-0305e82c3301. It is used as a practically-unique ID for database rows, files, messages and API resources without a central coordinator.

Which version does this generate?

This tool generates version 4 (random) UUIDs — the most common kind. All bits except the version and variant markers are cryptographically random, so the chance of a collision is negligible.

Are these UUIDs random and secure?

Yes. They are generated with your browser's cryptographically secure random number generator (crypto.getRandomValues / crypto.randomUUID). Everything happens in your browser — nothing is sent to a server and nothing is stored.

Is a UUID guaranteed to be unique?

Not guaranteed, but the odds of a version-4 collision are so small (1 in 2122) that for all practical purposes they are unique. You would need to generate billions per second for many years to have a realistic chance of a duplicate.

What is the difference between UUID and GUID?

They are the same thing. GUID (Globally Unique Identifier) is the name Microsoft uses; UUID is the name in the RFC 4122 standard. The format and randomness are identical.

Can I generate many at once?

Yes. Choose how many (up to 100), pick uppercase, braces or hyphen-less formatting if you need it, generate, and copy them all with one click.