Skip to main content
← Home

UUID Generator

Generate universally unique identifiers

What is a UUID?

A UUID is a 128-bit ID written as 32 hexadecimal digits in five groups; the 13th digit is the version. v7 (the default) starts with a millisecond timestamp, so new IDs sort in creation order — a good fit for database primary keys. v4 is fully random and reveals nothing about when it was created. v1 holds a timestamp and a node ID and is only needed for older systems.

Examples

UUID v7 — the first 48 bits are a Unix timestamp in milliseconds
0190b5c4-7e1a-7c3d-9f42-3b8e6d1a2c55
UUID v4 — 122 random bits; the 13th digit is always 4
f47ac10b-58cc-4372-a567-0e02b2c3d479

Frequently asked questions

Which UUID version should I use?

Use v7 for new database primary keys: it is unique and sorts by creation time, which keeps B-tree indexes compact. Use v4 when you need an ID that reveals nothing about when it was created. Use v1 only when an existing system requires it.

Can two generated UUIDs be the same?

In practice, no. A v4 UUID has 122 random bits; you would need to generate billions of IDs per second for decades before a collision became likely. v7 adds a timestamp on top of random bits, which makes duplicates even less likely.

Is a UUID the same as a GUID?

Yes. GUID is Microsoft's name for the same 128-bit format defined in RFC 9562 (formerly RFC 4122).

Are the UUIDs generated on a server?

No. They are created in your browser and are not sent or stored anywhere.

Related tools