UUID Generator — Free Online Tool

🆔 UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit identifier designed so that the odds of two independently generated UUIDs colliding are practically zero, making them ideal for database primary keys, distributed system IDs, session tokens and anything else that needs a unique identifier without a central authority handing out sequential numbers. This tool generates cryptographically random Version 4 UUIDs (the most common type, sometimes also called GUIDs) instantly.

You can generate a single UUID for a quick copy-paste, or a whole batch at once for seeding test data or configuration files.

How to use the UUID Generator

Choose how many UUIDs you want to generate.
Click generate.
Copy a single UUID or all of them at once.

How a Version 4 UUID is structured

A UUID v4 is 128 bits, displayed as 32 hexadecimal characters grouped into five sections separated by hyphens (8-4-4-4-12), for example 3f2504e0-4f89-41d3-9a0c-0305e82c3301. Of those bits, 122 are randomly generated, while a few fixed bits mark the UUID as version 4 and set the variant — this is what allows different systems to generate UUIDs independently with an astronomically low chance of collision, without needing to coordinate with each other.

Frequently asked questions

Can two generated UUIDs ever be the same?

In theory yes, but the probability is astronomically small — with 122 random bits, you'd need to generate billions of UUIDs per second for centuries before a collision became statistically likely. For all practical purposes, UUID v4 values are treated as unique.

What's the difference between a UUID and a GUID?

They're effectively the same concept — GUID (Globally Unique Identifier) is Microsoft's terminology, while UUID is the more general, cross-platform term defined by RFC 4122. Both refer to the same 128-bit identifier format.

Is this UUID generated securely, or is it predictable?

This tool uses the browser's cryptographically secure random number generator (Web Crypto API) where available, so generated UUIDs are not predictable from previous ones.