orbitHow to generate a UUID
A new UUID is created as soon as the page opens. Press Generate UUID for another one and Copy to put it on your clipboard.
What is a UUID?
A UUID (universally unique identifier), also called a GUID in the Microsoft world, is a 128-bit value written as 32 hexadecimal digits in five groups, for example 3f2b8c1e-9a4d-4e7b-b6a1-2c5d8e9f0a13. UUIDs let different systems create identifiers independently, without a central counter, and still avoid collisions.
Why version 4?
Version 4 UUIDs are generated from random numbers: 122 of the 128 bits are random, and the remaining bits mark the version and variant. You can recognise a v4 UUID by the 4 at the start of the third group. The chance of generating the same value twice is so small that it can be ignored in practice — you would need to create billions of UUIDs per second for many years to have a realistic chance of a duplicate.
Where UUIDs are used
- Primary keys in databases, especially distributed ones.
- Identifiers for API resources, files, sessions and messages.
- Test data and placeholders during development.
Frequently asked questions
Is this UUID really random?
Yes. It is generated by crypto.randomUUID, or crypto.getRandomValues in older browsers — both cryptographically secure.
Should I use UUIDs as secret tokens?
UUIDs are identifiers, not secrets. For passwords and access tokens use a dedicated generator such as the Password generator.