UUID Generator

Frequently asked questions

Which UUID version should I use?

v4 for general-purpose random IDs — the most common choice. v7 if the UUID is a database primary key and you want it to sort in creation order. v1 only if an existing system specifically requires the timestamp+node format. The nil UUID is a fixed placeholder/sentinel value, not a real identifier.

What is UUID v7 and why does it matter?

UUID v7 embeds a millisecond Unix timestamp in its first 48 bits, so newly generated UUIDs sort in roughly the same order they were created. That matters for database primary keys: UUID v4 is fully random, which scatters rows across a B-tree index and hurts insert performance at scale — v7 avoids that while still being a standard 128-bit UUID.

Are these UUIDs cryptographically random?

v4, and the random portions of v1 and v7, are generated with the Web Crypto API's getRandomValues — the same CSPRNG used for cryptographic keys. v1's node field is randomized rather than a real MAC address, since browsers can't read hardware addresses. The nil UUID is a fixed constant, not random at all.

Can I generate more than one UUID at a time?

Yes. Set the count field to any number from 1 to 1000. Above 1, the output becomes a list you can copy all at once or download as a .txt or .csv file.

Is my data uploaded anywhere?

No. UUIDs are generated entirely in your browser — nothing is sent to a server.