Bulk UUID generator

About UUIDs

A UUID (Universally Unique Identifier) is a 128-bit value usually written as xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx (8-4-4-4-12, or 32 hex digits). It is used for database keys, session tokens, idempotency IDs and anywhere you need an identifier that is unique without central coordination.

This page generates version 4 (random) UUIDs: one field is fixed to mark version 4 and the top bits of the next field are fixed to 10 (the RFC 4122 variant), while everything else is filled from a random source. Randomness uses the browser’s crypto.getRandomValues, with a Math.random fallback only on very old browsers.

The special value 00000000-0000-0000-0000-000000000000 is the nil UUID, used to mean "empty" or "unset" - it is never the output of a random generator like this.

Uniqueness of random UUIDs rests on probability: v4 has about 122 random bits, so collisions are effectively never seen, though they are not guaranteed impossible. For strongly consistent or security-critical uses, keep a uniqueness constraint in the database rather than relying on randomness alone.

The password page can also emit a single UUID; this page is for generating and copying them in bulk.

Frequently asked questions

Are these UUIDs really unique?

They are random version-4 UUIDs built from the browser’s crypto-grade random source. A collision is theoretically possible but, with 122 bits of randomness, so unlikely that they are treated as unique in practice.

What is the nil UUID?

00000000-0000-0000-0000-000000000000 is the "nil" UUID, used as an empty placeholder - a random generator like this one will never produce it.

How many can I generate at once?

Between 1 and 500 per batch; drag the slider or press Regenerate to make a new set.

Is anything uploaded?

No. UUIDs are generated locally on your device and are not stored or sent anywhere.