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UUID generator

Create unique identifiers for databases, APIs and test data. Version 4 is fully random, version 7 starts with a timestamp so new IDs sort in creation order.

Free and private. Everything runs in your browser, nothing is uploaded.

How it works

  1. Choose the versionv4 for general use, v7 for database keys that should sort by time.
  2. Set the formatNumber of IDs, uppercase, hyphens or braces.
  3. Copy or downloadCopy the list or download it as a text file.

v4 or v7?

UUID version 4 contains 122 random bits; the chance of two ever colliding is negligible. Version 7, standardised in RFC 9562, puts a millisecond timestamp in front of the random part. Because new v7 IDs are always larger than older ones, they keep database indexes compact and make records sortable by creation time, which is why many teams now prefer v7 for primary keys.

IDs generated within the same millisecond still sort in order, thanks to a counter in the random part.

Decode a UUID

Paste any UUID into the decoder to see its version and variant. For time based versions 1, 6 and 7 the decoder also shows when the ID was created, which helps when debugging logs and database rows. Everything runs in your browser.

Frequently asked questions

Are these UUIDs unique?

In practice yes. v4 has 122 random bits; v7 has 74 random bits per millisecond plus a counter.

What is the difference between UUID and GUID?

GUID is Microsoft's name for the same thing. They are often written in uppercase and in braces.

Can I see when a UUID was created?

For versions 1, 6 and 7, yes. Paste it into the decoder.

Are the IDs sent anywhere?

No. They are generated in your browser.