Image tools

UUID Generator

Generate up to 5,000 random version 4 UUIDs at once, from your browser's cryptographic random source.

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

How to use UUID Generator — Free Online Random UUID v4 / GUID Tool

  1. 1Pick what you want to generate and how many.
  2. 2Set the length or number range, and any formatting options.
  3. 3Copy the whole list, download it as a text file, or press Regenerate for a fresh set.

About UUID Generator

UUIDs solve a specific problem: generating an identifier that is unique without asking anyone else first. Two services on opposite sides of the world can each mint one and be confident they will not clash, which is why they appear throughout distributed systems, file formats and APIs.

Version 4 gets that property from sheer size. With 122 random bits, the space is large enough that collisions are a theoretical concern rather than a practical one — the often-quoted figure is that you would need billions of UUIDs per second for a century before it became worth worrying about.

These are generated with your browser's cryptographic random source rather than Math.random, which matters if the identifier will be used anywhere it should be unguessable as well as unique.

Frequently asked questions

What is a UUID version 4?
A UUID generated from random data rather than from a timestamp or MAC address. 122 of its 128 bits are random, with the remaining bits marking the version and variant.
Can two UUIDs ever collide?
In theory yes, in practice no. You would need to generate about 2.7 quintillion v4 UUIDs before the chance of a single collision reached even one in a billion.
Is a UUID the same as a GUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier, sometimes written in braces like {xxxxxxxx-xxxx-...}. Use the brace option to match that format.
Are these truly random?
They come from crypto.getRandomValues, your browser's cryptographically secure random source — not Math.random. Nothing about them is derived from your device or shared with anyone.
Should I use a UUID as a database primary key?
It works and avoids coordination between services, but random UUIDs scatter inserts across a B-tree index, which hurts write performance at scale. UUID v7 or an ordered ID is better where that matters.
Is it free?
Yes — unlimited use, no sign-up, no watermark and no limit on how many times you run it.