🆔 UUID Generator
Generate one or many RFC 4122 version-4 UUIDs (universally unique identifiers) for use in code, databases, or testing.
About UUID Generator
This tool generates RFC 4122 version 4 UUIDs — 128-bit identifiers that look like 550e8400-e29b-41d4-a716-446655440000 — one at a time or in batches of up to 500. They're commonly used as primary keys in databases, request IDs in API logs, session tokens, and unique filenames, particularly in distributed systems where multiple services need to generate IDs independently without coordinating with each other.
Generation uses the Web Crypto API rather than Math.random(), so the random bits underlying each UUID come from a cryptographically secure source. Version 4 means the UUID is almost entirely random: 122 of its 128 bits are random, with the remaining 6 fixed to mark the version and variant per the RFC 4122 spec — which is what makes it recognizable as a v4 UUID rather than some other version.
You can toggle hyphens off for contexts that expect a bare 32-character hex string, and toggle uppercase for systems that expect that convention — both are valid per the spec, since case and hyphenation aren't part of the identifier's identity. Generating up to 500 at once is handy for seeding test data or database fixtures, though for genuinely large batches you'd typically generate UUIDs in application code instead.
Frequently asked questions
What is a UUID used for?
UUIDs are widely used as unique identifiers for database records, API objects, and distributed systems — the odds of two random UUIDs colliding are astronomically small.
What UUID version does this generate?
Version 4 (random) — the most common type, generated using cryptographically secure randomness via the Web Crypto API.
What does a UUID actually look like?
A 36-character string such as 550e8400-e29b-41d4-a716-446655440000: 32 hexadecimal digits grouped 8-4-4-4-12 by hyphens, with version and variant markers embedded at fixed positions.
Can two randomly generated UUIDs ever collide?
Practically no. Version 4 UUIDs have 122 random bits — you'd need to generate roughly 2.71 quintillion of them before there's even a 50% chance of a single collision.
Should I use UUIDs as database primary keys?
They work well and avoid collisions across distributed systems, but they're larger than auto-incrementing integers (16 bytes vs. 4-8) and, being random, don't sort chronologically or index as efficiently in some databases.