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Please take a number
v4 · random
Take a number · now serving · tear here
UUID/GUID Generator
Pull the tab and a ticket tears off with a fresh identifier. Random v4 for most jobs, time-ordered v7 for database keys, v1 when something old expects it. Take a hundred at once, copy them, or read one you already have.
Read a ticket
One ticket, never issued twice
A UUID is a 128-bit number written as 32 hex digits in five groups. Version 4 is 122 random bits: the chance of two ever colliding is so small that nobody coordinates them, which is the whole point. Version 7 puts a millisecond timestamp in the first 48 bits and random bits after, so tickets sort by the time they were taken, which databases love. Version 1 is the 1990s original, a 100-nanosecond timestamp plus a clock sequence and a node address; here the node is random, as the standard allows.
Reading one
The third group's first digit is the version; the fourth group's first digit encodes the variant (8, 9, a or b for the standard layout). Paste a v1 or v7 ticket into the reader and it prints the time buried in it; paste a v4 and it confirms there is nothing to read.
Why a take-a-number dispenser
The red dispenser at the deli counter hands out numbers in order with no argument and no clerk: pull the tab, tear the ticket, wait for the sign. A UUID generator is the same machine for computers, except the tickets are 128 bits long and the queue is the whole world.
Are these cryptographically random?
Yes. Every random bit comes from the browser's crypto.getRandomValues, the same source used for keys.
GUID or UUID?
The same thing; GUID is Microsoft's name for it. The braces option prints the Windows registry style.
Is anything uploaded?
No. The tickets are generated and stay in your browser.
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