Generate unique identifiers in bulk — fully random v4, or v7 which sorts in creation order. Uppercase and hyphen-free forms are one toggle away.
Questions
Are generated values stored or sent?
No. They are made in the browser and disappear when the page closes.
Does v7 reveal when it was created?
Yes — the timestamp is right there in the leading bits. Use v4 where that matters.
Can I use one as a password?
Not advisable. UUIDs are not treated as secrets and routinely appear in URLs and logs. Use the password generator when you need a secret.
Does case matter?
By the specification, generators emit lowercase and parsers accept either — so they are the same value. Systems that compare the text directly will disagree, though, so switch to uppercase only when the destination asks for it. Lowercase is the default here.
Why is v7 faster as a database primary key?
Because of how the index grows. v4 is fully random, so new rows land all over the index and pages split constantly. v7 leads with a timestamp, so new rows land at the end — closer to an append, which keeps writes cheap and fragmentation low.
How many can I generate at once?
Up to 50. Needing more than that in one go usually means a program is doing the generating rather than a person, and in that case calling your language’s own UUID function is more reliable than pasting from a page. Almost every language ships one.