UUID Generator
Create random UUID v4 unique identifiers, from 1 to 100 at a time, uppercase or lowercase, with or without dashes. Everything happens in your browser.
What is a UUID v4 and when to use one
A UUID (Universally Unique Identifier) version 4 is a 128-bit code, 122 bits of which
are generated at random — for example 3f9a2c1e-8b4d-4e7a-9c2f-1d6e8a0b5c3d.
The odds of two UUID v4 values colliding are so tiny they are negligible in practice: you
would need to generate roughly 2.7 quintillion of them to reach a 50% chance of a single
collision. That is why they are the go-to choice for primary keys in distributed databases,
session identifiers, unique file names, and request IDs in APIs — no central counter needed
to keep multiple systems in sync.
Are UUIDs generated in the browser secure?
Yes: this page uses crypto.randomUUID(), the native API in modern browsers
that draws from the operating system's cryptographic random number generator (with
crypto.getRandomValues() as a fallback for older browsers). It never uses
Math.random(), which is predictable and unsuitable for generating identifiers.
A neat detail about the format: the first digit after the second dash is always "4" (the
version), and the first character of the next block is always 8, 9, a, or b (the variant).