UUID Generator (v4)

Create random version 4 UUIDs with your browser's cryptographic random generator — one or a thousand at a time — and copy or download them. You can also paste any UUID to see which version it is.

Generate UUIDs

Version 4 · cryptographically secure randomness.

UUIDs (version 4)

Options

How many Uppercase Hyphens Braces { }

Check a UUID

How to use it

Set how many UUIDs you need (up to 1,000) and click Generate.
Choose the format: uppercase, with or without hyphens, or wrapped in braces as some Microsoft tools expect.
Copy one UUID, Copy all (one per line) or download them as a text file.
To identify an existing UUID, paste it into "Check a UUID".

Good to know

Secure randomness: UUIDs come from crypto.randomUUID() or crypto.getRandomValues(), the browser's cryptographically secure generator. If neither is available the tool refuses instead of falling back to Math.random().
How unique is a v4 UUID?: Each one has 122 random bits. You would need to generate about a billion UUIDs per second for around 85 years to reach a 50% chance of a single duplicate.
UUID or GUID?: They are the same thing. GUID is Microsoft's name and is often written in uppercase with braces.

Frequently asked questions

What is a version 4 UUID?

A 128-bit identifier made almost entirely of random bits, written as 32 hex digits in the pattern 8-4-4-4-12. The "4" at the start of the third group marks the version.

Are these UUIDs stored anywhere?

No. They are created in your browser and disappear when you leave the page.

Can I use them as database primary keys?

Yes, v4 UUIDs are widely used as keys. For very large tables, time-ordered UUIDs (v7) index better, but v4 is fine for most applications.

Why not use Math.random() to make UUIDs?

Math.random() is not designed to be unpredictable or unique. A cryptographic generator is the safe choice for identifiers.