UUID generator

How it works

A version 4 UUID is 128 bits, almost all of them simply random: 122 random bits, plus 6 fixed ones marking it as version 4 with the standard variant. Those fixed bits are why every v4 UUID has a 4 starting its third group, and an 8, 9, a, or b starting its fourth. The appeal is that no coordination is needed — two machines that have never spoken can each generate one and be safe assuming they will not collide, because with 2¹²² possibilities the odds are negligible even across billions of IDs. These are generated in your browser by crypto.randomUUID(), never sent anywhere, and never seen by this site.