What is UUID?
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit identifier written as 32 hexadecimal digits in five groups (8-4-4-4-12). UUIDs are generated to be unique across space and time without a central authority, so different systems can create IDs that practically never collide.
A UUID looks like 550e8400-e29b-41d4-a716-446655440000. The most common is version 4, which is random; other versions derive from time, namespace or a hash. With 122 random bits, accidental collisions are astronomically unlikely.
UUIDs are used as database primary keys, distributed-system identifiers and idempotency keys — anywhere you need a unique ID without coordinating with a central counter.
UUID tools
UUID Generator
Generate UUIDs online — v1, v4, v7, and Nil. Bulk generation up to 10,000. Free, no signup.
Open toolPassword Generator
Generate strong, cryptographically random passwords. Configurable length and character sets — runs in your browser.
Open toolRandom JSON Generator
Generate fake JSON from a schema using faker.js. Multi-output: JSON, CSV, TSV, XML. Free, runs in your browser.
Open toolFrequently asked questions
Is a UUID the same as a GUID?
Yes — GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit UUID format.
Can two UUIDs ever collide?
In theory yes, in practice no — a version-4 UUID has 122 random bits, so collisions are astronomically unlikely.