Version 1 UUID — A universally unique identifier created from a timestamp and a node field. The classic idea referred to hardware addresses; this generator never reads your MAC — it uses the RFC 4122 layout with random clock and node bits, so you get time-ordered structure without exposing real hardware.
Version 4 UUID — A universally unique identifier built from random data. Values from this site use the browser’s cryptographically strong random number generator.
Version 7 UUID — Defined in RFC 9562: a Unix timestamp in milliseconds in the leading bits, plus version bits and more randomness. Handy when you want IDs that sort roughly by creation time while staying unpredictable.
GUID — Microsoft’s name for the same 128-bit layout as a UUID. Different products used different algorithms in the past; here, “GUID” means the same secure random construction as Version 4 — same format, familiar label.
Nil / empty UUID — The reserved all-zero form 00000000-0000-0000-0000-000000000000, often used as a placeholder or sentinel.
Case — Only affects hex letters (a–f vs A–F); hyphens and digits stay as shown.
Settings stay in your browser. Nothing is sent to a server unless you use Share UUID.
Enter your PIN to show your history.
A forgotten PIN cannot be recovered. The only way past this screen is to clear what it is protecting.