UUID Generator
Generate random UUID v4 identifiers, one or many at a time.
Generate cryptographically random UUID v4 identifiers — one at a time or in a batch — using your browser's secure random number generator.
What a UUID looks like
A UUID (universally unique identifier) is 128 bits, written as 32 hexadecimal characters in five groups: 8-4-4-4-12. For example:
3f2b8c1e-9d4a-4f6b-a2c7-5e8d1b9f0a34
In a version 4 UUID, the first digit of the third group is always 4, and the first digit of the fourth group is always 8, 9, a or b. The other 122 bits are random.
Where UUIDs are used
- Database keys: records can get a unique ID without asking a central server for the next number.
- APIs and URLs: random IDs don't reveal how many records you have, unlike 1, 2, 3…
- Files and uploads: naming uploaded files by UUID prevents two users' files from overwriting each other.
- Distributed systems: separate servers and devices can create IDs at the same time without clashing.
- Testing: fill test data with realistic unique IDs.
UUID versions
| Version | Based on | Notes |
|---|---|---|
| v1 | Time and device address | Can reveal when and where it was created |
| v4 | Random numbers | The most widely used; what this tool makes |
| v7 | Time plus random bits | Newer; sorts by creation time, which suits database indexes |
How unique is it?
With 2122 possible values (about 5.3 × 1036), you'd need to generate around a billion UUIDs every second for about 86 years before reaching a 50% chance of a single duplicate.
Frequently asked questions
What version of UUID does this generate?
Version 4 — randomly generated, using your browser's cryptographically secure random number generator. It's the most common type for general-purpose unique IDs.
How unlikely is a collision?
Extremely — there are 2^122 possible v4 UUIDs, so even generating billions of them, the odds of a duplicate are effectively zero.
Is a UUID the same as a GUID?
Yes, effectively. GUID (globally unique identifier) is Microsoft's name for the same 128-bit format.
Can I use a UUID as a password or secret token?
A v4 UUID made with a secure random generator, like this one, is hard to guess, but it's designed as an identifier, not a secret. For passwords and API secrets, use a purpose-made generator such as the password generator.