Submit a tool

UUID Generator

Generate random v4, time-ordered v7 or nil UUIDs — one or a thousand at once. Choose uppercase or hyphen-free output, copy or download, all in your browser.

What UUIDs are good for

A UUID lets two systems mint identifiers without coordinating — no shared counter, no central database round-trip. That's why they show up as primary keys, idempotency keys, trace IDs and upload file names. With 122 bits of randomness in a v4 UUID, you can generate them all day and never realistically hit a collision.

How to use it

  1. Pick a version. Stick with v4 unless you want time-sortable keys, in which case choose v7.
  2. Set the count. Generate a single ID or up to a thousand at once for seeding test data.
  3. Format and grab them. Toggle uppercase or hyphen-free output, then copy everything or download a .txt file.

v4 vs. v7 at a glance

  • v4 is 122 random bits — unpredictable and order-free. The right default when you just need a unique value.
  • v7 prefixes a millisecond timestamp, so IDs sort by creation time. Great for database keys, where sequential inserts keep the index tidy.
  • Nil is all zeros — a sentinel for "no ID yet".

Frequently asked questions

What is a UUID?

A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups (8-4-4-4-12). They're used as database keys, request IDs and file names because they can be generated independently with virtually no chance of collision.

v4 or v7 — which should I use?

Version 4 is fully random and the safe default for most needs. Version 7 starts with a millisecond timestamp, so the IDs sort in roughly the order they were created — which makes them friendlier as database primary keys because new rows append to the end of the index.

Are these UUIDs really unique?

A v4 UUID has 122 random bits, so the odds of two ever colliding are astronomically small. The randomness comes from the browser's cryptographic generator (crypto.getRandomValues), the same source used for keys and tokens.

What is the nil UUID?

The nil UUID is all zeros (00000000-0000-0000-0000-000000000000). It's a special value used to represent 'no UUID' or an unset identifier, similar to null.

Are the UUIDs generated privately?

Yes. Every UUID is generated locally in your browser. Nothing is requested from or sent to a server, so the IDs are never seen by anyone but you.