UUID Generator
Bulk UUID v4 identifiers from crypto-grade randomness — uppercase and hyphen-free options, copy one or copy all.
How to use
- Set how many UUIDs you need (1–100).
- Press Generate — toggle uppercase or no hyphens any time to re-format.
- Copy a single UUID or copy the whole list.
Frequently asked questions
What is a version 4 UUID?
A UUID v4 is a 122-bit random identifier formatted as 8-4-4-4-12 hex digits (36 characters with hyphens). The version nibble is fixed to 4 and the variant bits to the RFC 4122 layout; everything else comes straight from a cryptographically secure random generator.
How unlikely is a collision?
Astronomically unlikely. You would need to generate billions of UUIDs per second for over a century to have a coin-flip chance of one duplicate. For all practical purposes, every UUID this tool produces is unique.
Why does randomness quality matter?
UUIDs often act as unguessable identifiers (session or API keys). Math.random() is predictable; crypto.getRandomValues is seeded from the operating system entropy pool, so its output cannot be predicted from previously seen values.
Should I use uppercase or no hyphens?
They are cosmetic. Comparison and storage usually normalize to lowercase with hyphens; uppercase and hyphen-free forms are common in Windows registry keys, file names or URLs where brevity or case-insensitive systems matter. Both options only change the display.
Are the UUIDs sent anywhere?
No. They are generated in your browser from local entropy — nothing is requested, logged or stored.