UUID Generator

How to use the uuid generator

1. Choose how many UUIDs you need.
2. Set uppercase or hyphen-free formatting if required.
3. Copy or download the list.

About this tool

A UUID is a 128-bit identifier that can be generated independently by many systems without coordination and still be practically guaranteed unique. Version 4 UUIDs are almost entirely random — 122 random bits, with six bits fixed to mark the version and variant.

That independence is the point: two services can create records offline and merge them later without a central sequence handing out numbers. The trade-off is size and randomness — UUIDs index less efficiently than sequential integers, which is why some databases prefer time-ordered variants for primary keys.

Common uses

• Seeding test data with unique identifiers.
• Creating a correlation ID for tracing a request.
• Naming uploaded files without collisions.

Frequently asked questions

Can two v4 UUIDs collide?

In theory yes, in practice no. With 122 random bits you would need to generate billions per second for a century before a collision becomes likely.

Are these UUIDs random enough for security?

They come from the browser's cryptographic random source, so they are unguessable. Even so, a UUID is an identifier, not a secret — do not use one as an authentication token on its own.