UUID Generator

Generate version 4 UUIDs in your browser

This free UUID generator creates random version 4 UUIDs using your browser's cryptographically secure random source. Generate one or up to fifty at a time, optionally uppercase or without hyphens, and copy them individually or all at once. Nothing is sent to a server, so the identifiers are generated entirely on your device.

No signup, no limits, no ads. Click generate as many times as you like.

How to use it

1. Set how many UUIDs you want, from 1 to 50.
2. Toggle formatting with the uppercase and hyphens options if you need a specific shape.
3. Click generate to produce a fresh batch.
4. Copy a single UUID with its row button, or copy the whole batch with copy all.

Common use cases

• Database primary keys. Generate stable, collision-resistant ids without a central sequence.
• Request and trace ids. Tag a request so you can follow it across logs and services.
• Idempotency keys. Give an API call a unique key so retries do not double-charge or double-create.
• Test fixtures. Seed test data with realistic unique identifiers.
• File and asset names. Use the no-hyphen form for short, unique, collision-free names.

What a version 4 UUID is

A UUID is a 128-bit identifier written as 32 hexadecimal digits in five hyphen-separated groups, like 123e4567-e89b-42d3-a456-426614174000. The version 4 variant fills almost all of those bits with random data, reserving a few to mark the version and variant. Because the space of possible values is so vast, two independently generated version 4 UUIDs will not collide in any realistic scenario, which is exactly why they are the default choice for distributed systems that need unique ids without coordination.

Frequently asked questions

Are these UUIDs generated on a server?

No. They are generated in your browser using the built-in crypto.randomUUID function, which is backed by the operating system's cryptographically secure random source. Nothing is sent over the network, so the values are yours alone.

What version of UUID is this?

Version 4, the random variant. 122 of its 128 bits are random, which makes accidental collisions astronomically unlikely. Version 4 is the right default for database keys, request ids, and idempotency keys.

Are they safe to use as primary keys?

Yes. Version 4 UUIDs are random enough that you can generate them independently on many machines without coordination and never realistically collide. The trade-off versus an auto-increment integer is size and index locality, not uniqueness.

Can I generate many at once?

Yes, up to 50 per batch. Use the count field, then copy any single value or copy all of them at once as a newline-separated list.

What do the uppercase and hyphens options do?

Uppercase prints the hex digits in capitals (some systems expect that). Removing hyphens gives you the compact 32-character form with no dashes, handy for filenames or compact identifiers. Both are purely cosmetic; the underlying value is the same.

Will I get the same UUID twice?

In practice, no. With 2 to the 122 possible values, you would have to generate billions of UUIDs per second for many years before a collision became likely. Each click produces fresh values.