UUID v4 Generator

A version 4 UUID is 122 random bits formatted as 36 characters, giving effectively zero chance of collision without any central coordination. That is why they are used for database keys, correlation ids, and file names. This generator uses the browser’s cryptographic random source and can produce up to 500 at a time.

How to use it

1. Set how many UUIDs you need.
2. Choose a format: standard lowercase, uppercase, no hyphens, or braced GUID style.
3. Press Generate.
4. Copy the whole list in one click.

Frequently asked questions

How likely is a UUID collision?

Negligible. You would need to generate about 2.7 × 10¹⁸ UUIDs to reach a one-in-a-billion chance of a single duplicate — more than any practical system will ever create.

What is the difference between a UUID and a GUID?

None, functionally. GUID is Microsoft’s name for the same 128-bit identifier, conventionally written in braces. The bytes are identical.

Should I use a UUID as a database primary key?

It depends. UUIDs avoid coordination between services but harm index locality in B-tree databases because inserts land randomly. UUID v7, which is time-ordered, exists specifically to solve that.

Are these UUIDs cryptographically random?

Yes. They come from crypto.randomUUID, backed by the platform’s CSPRNG, not from Math.random.

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