UUID Generator (v4)

A UUID is a 128-bit identifier written as 32 hexadecimal digits, like 3f2b8c1e-9a4d-4e7b-8c21-5d6f0a9b7e34. Version 4 UUIDs are random, so you can create them anywhere, with no central counter, and still expect them to be unique.

Runs entirely in your browser. Nothing you enter is sent to a server.

How to use it

  1. Choose how many UUIDs you need.
  2. Optionally switch to uppercase or remove the hyphens.
  3. Press Generate new UUIDs, or just change an option.
  4. Copy the list.

Format

  • Layout: 8-4-4-4-12 hexadecimal digits.
  • The first digit of the third group is always 4 (the version).
  • The first digit of the fourth group is 8, 9, a or b (the variant).
  • 122 of the 128 bits are random, so a collision is practically impossible.

Frequently asked questions

Are these UUIDs really random?
Yes. They come from the cryptographic random generator built into your browser, the same one used for security features.
Can two people generate the same UUID?
In theory yes, in practice no. With 122 random bits you would need to generate billions of UUIDs per second for many years to have a meaningful chance of a repeat.
What is the difference between UUID and GUID?
Nothing in practice. GUID is the name Microsoft uses for the same 128-bit identifier format.
Should I use UUIDs as database keys?
It works, but fully random keys scatter inserts across an index. Some databases prefer time-ordered IDs (such as UUID v7) for large tables.

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