UUID generator
Cryptographically random version-4 UUIDs — generate one or a whole batch at once.
Identity without a registry
The problem a UUID solves is coordination. When one central database hands out numbers — 1, 2, 3 — uniqueness is easy. But the moment records are created independently — a phone app working offline, three servers behind a load balancer, two spreadsheets merged months apart — sequential numbers collide on day one. A version-4 UUID sidesteps the question entirely: each side rolls its own 122 random bits, and the space of outcomes is so vast that nobody ever needs to ask anyone else. That is why you meet them as database keys, order references, upload file names, and the correlation IDs that let you follow a single request through a pile of server logs.
Batches, hyphens and case
Set How many as high as 1000 and you get one UUID per line, ready to paste into a spreadsheet column, a test fixture or a seed script — handy when you need placeholder records guaranteed never to clash with real ones. The two formatting switches exist because systems disagree about cosmetics: untick Include hyphens for the compact 32-character form some databases and APIs prefer, and tick Uppercase where a style guide demands it. Neither changes the identity — upper and lower case spell the same value in hexadecimal — so you can reformat an existing ID without breaking references, provided the system reading it is equally relaxed about case.
Unique is not the same as secret
A random UUID is unpredictable enough that nobody can guess the next one, which makes it fine to expose in a URL — an order page at /a1b2c3 tells a visitor nothing about how many orders exist, unlike an order page at /1042. But resist promoting it into a password or an API key: it was never designed as a credential, and once an identifier has appeared on screens, in logs and in bookmarks, it is public by definition. Keep names and secrets in separate drawers. This generator is free without limits, like the whole Developer & Data category — and on the day you need a secret rather than a name, make it with the password generator instead.
What a v4 UUID actually is
A UUID is a 128-bit identifier designed to be unique without any central coordination. Version 4 means it's generated from random bits (rather than derived from time or a network address) — the odds of two colliding are astronomically small, which is why they're the default choice for database keys, tracking IDs and file names.
Can two UUIDs from this tool collide?
In practice, no — a v4 UUID has 122 random bits. You'd need to generate billions of them per second for centuries before a collision became likely.
Is my data sent anywhere?
No — UUIDs are generated entirely in your browser using the Web Crypto API. Nothing is uploaded.
