UUID Generator

v4 is fully random — the classic UUID. v7 (RFC 9562) puts a millisecond timestamp in its first 48 bits, so v7 IDs sort chronologically by when they were created. That makes v7 a better choice for database primary keys, because new rows insert in order instead of scattering across the index.

Yes. They use the browser's Web Crypto API (crypto.getRandomValues), a cryptographically-secure source — never the predictable Math.random. The version and variant bits are set exactly per RFC 9562, so every UUID is valid.

No. There is nothing to upload — the UUIDs are generated on your device, and there is no network request in the generation path. Open your browser's Network tab while you generate and you'll see no traffic.

Yes, up to 1000 in a single batch, all guaranteed distinct. Use Copy all to grab the whole list, one UUID per line.

v7 embeds a timestamp, and within a single batch we also add an ordering counter, so a batch you generate at once is strictly increasing. Sort a column of v7 UUIDs and you've sorted it by creation time.

No. They only change how it's written. The underlying value is identical — you can always convert back to the canonical lowercase, hyphenated form.