UUID Generator

Generate random version 4 UUIDs (GUIDs) one at a time or in bulk.

How to use the UUID generator

Enter how many identifiers you need, choose a format and press Generate UUIDs. Each UUID appears on its own line, ready to paste into a database script, a configuration file or test data. Copy all places the whole list on your clipboard.

How version 4 UUIDs work

A UUID is 128 bits long. In version 4, sixteen random bytes are generated, then four bits of the seventh byte are set to 0100 to mark version 4 and the top two bits of the ninth byte are set to 10 to mark the standard variant. That is why the third group always starts with 4 and the fourth group always starts with 8, 9, a or b.

When to use them

Random UUIDs suit primary keys created on several machines, file names, request and trace IDs, and idempotency keys. They are not secrets by design, so do not use a UUID as a password or as the only protection for a private link unless it comes from a secure random source, as these do.

Frequently asked questions

What is a UUID?

A UUID (universally unique identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in five groups, for example 3f2b8c1e-9d4a-4b7c-8e21-5a6f0c9d1e3b. It lets systems create identifiers without a central authority.

What is a version 4 UUID?

Version 4 UUIDs are random. 122 of the 128 bits come from a random source; the remaining six bits mark the version (4) and the variant defined in RFC 9562 (formerly RFC 4122).

Can two generated UUIDs be the same?

In theory yes, in practice no. With 122 random bits there are about 5.3 × 10^36 possible values. You would need to generate roughly 2.7 × 10^18 UUIDs to reach a 50% chance of a single collision.

Are these UUIDs generated on a server?

No. They are created in your browser with crypto.randomUUID or crypto.getRandomValues and are never transmitted or stored.

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