UUID Generator

How it works

A UUID is a 128-bit identifier written as 32 hexadecimal digits in five dash-separated groups. Version 4 fills those bits with random data apart from the six that record the version and the variant, which is why every value here has a 4 at the start of the third group.

Randomness comes from the Web Crypto API, not from Math.random, so the values are suitable as identifiers that must not be guessable or collide across machines. When the browser provides crypto.randomUUID it is used directly; otherwise the same bits are assembled from cryptographic random bytes.

Generate between 1 and 50 at a time and copy the whole list in one click. Web Crypto is only available in a secure context, so the page has to be served over HTTPS.

Frequently asked questions

What does the 4 in a version 4 UUID mean?

It is the version field, stored in the first digit of the third group. It records that the remaining bits were generated randomly rather than from a timestamp or a MAC address.

Can two version 4 UUIDs ever collide?

In theory yes, in practice no. With 122 random bits you would need to generate billions of values per second for decades before a collision became likely, which is why they are safe to create independently on many machines.

What is the difference between UUID v4 and v7?

Version 4 is fully random, so values sort arbitrarily. Version 7 puts a timestamp in the leading bits, which makes identifiers sort by creation time and index better in a database. This tool generates version 4.

Are UUID and GUID the same thing?

Yes. GUID is Microsoft's name for the same 128-bit identifier format. A GUID from .NET or SQL Server is interchangeable with a UUID generated here.

Are the generated UUIDs unique to me?

They are generated in your browser and never transmitted, so no one else receives them or can predict them. Reload the page and you get an entirely new set.