About UUID Generator
UUID Generator creates version 4 (random) UUIDs — the format defined by RFC 4122 for identifiers that are unique enough to assign without any central coordination — entirely in your browser. Each one is generated with crypto.randomUUID(), the browser's built-in cryptographically secure UUID generator, so the odds of two colliding are astronomically small even across billions of IDs. Generate one at a time or in bulk, with or without hyphens, in upper or lower case. Nothing you generate here is uploaded or logged.
How to use it
- 1
Set how many you need
Drag the count slider to choose how many UUIDs to generate at once (1-100).
- 2
Choose a format
Toggle hyphens on or off, and switch between lowercase and uppercase hex digits.
- 3
Copy them
UUIDs regenerate automatically whenever you change an option. Click Copy to copy the full list, one per line.
What it does
- Generates RFC 4122 version 4 (random) UUIDs using crypto.randomUUID()
- Generates in bulk — from a single UUID up to 100 at once
- Toggles hyphenated (8-4-4-4-12) vs. unhyphenated formatting
- Toggles lowercase vs. uppercase hex digits
FAQ
What's the difference between a UUID and a GUID?
They're effectively the same thing — GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit identifier format standardized as UUID (Universally Unique Identifier) in RFC 4122. A UUID generated here works anywhere a GUID is expected.
Why version 4 specifically?
UUID versions differ in how they're derived — version 1 encodes a timestamp and MAC address, version 3/5 hash a namespace and name, and version 4 is just 122 bits of randomness (6 bits are fixed to mark the version and variant). Version 4 is the most common choice for general-purpose unique IDs since it needs no coordination or input data, just a good random source.
Can two generated UUIDs ever collide?
In theory yes, in practice effectively never — there are 2^122 possible version 4 UUIDs, so even generating a billion per second for a hundred years would use only a negligible fraction of the space. Collisions are not a realistic concern for this format.
Does this tool send anything to a server?
No. Every UUID is generated locally using the browser's built-in crypto.randomUUID() and never leaves your machine.