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).