UUID Generator: how to use it

Generate random version 4 UUIDs in bulk, in lowercase or uppercase, using your browser's secure random source. Learn when UUIDs are the right choice.

Open the UUID Generator →

Developer tools · Updated 24 October 2026

A UUID (universally unique identifier) is a 128-bit label written as 32 hexadecimal digits in five groups, for example 123e4567-e89b-42d3-a456-426614174000. Developers use them as database keys, file names, order references and test data because two systems can create them independently with practically no risk of collision.

This generator makes version 4 UUIDs, which are based on random numbers produced by your browser's cryptographic random generator.

How to use the UUID Generator

Choose Number of UUIDs: 1, 5, 10, 25, 50 or 100.
Choose the Format: lowercase or uppercase.
Press Generate UUIDs.
Press Copy all to copy the list, one UUID per line, or Clear to reset.

Tips for better results

Lowercase is the common convention. Uppercase is mostly used for compatibility with older systems.
The "4" at the start of the third group and the 8, 9, a or b at the start of the fourth group identify the version and variant. You can use them to confirm that a value is a version 4 UUID.
A UUID is not a secret. Do not use one as a password or an access token on its own.
If you need sortable IDs by creation time, look at newer ordered UUID or ULID formats instead.

How unlikely is a collision?

There are about 5.3 x 10^36 possible version 4 values. You would have to generate billions per second for many years before a duplicate became likely, so for practical purposes you can treat them as unique.