Versions & formats
Compare the structure, characteristics, and best use of each identifier version and format at a glance.
UUID v1 time
The first UUID version, generated from time and a node (usually a MAC address).
UUID v3 name / MD5
A deterministic UUID created by hashing a name and namespace with MD5.
UUID v4 random
The most widely used standard UUID, built from 122 random bits.
UUID v5 name / SHA-1
A deterministic UUID created by hashing a name and namespace with SHA-1.
UUID v7 time-sortable
The latest UUID, storing Unix milliseconds in the first 48 bits so it sorts chronologically.
NIL UUID zero
A special UUID in which every bit is zero.
GUID Microsoft
The Microsoft-style notation for a UUID, usually wrapped in braces and uppercase.
ULID Base32
A short, time-sortable identifier written as 26 characters of Crockford Base32.
NanoID URL-safe
A compact identifier of URL-safe characters, 21 characters by default.