UUID Generator

What is a UUID?

A UUID (Universally Unique Identifier, also called a GUID) is a 128-bit identifier written as 36 characters: 123e4567-e89b-42d3-a456-426614174000. Version 4 UUIDs — what this tool generates — are made of 122 random bits, which is why two systems can mint IDs independently, with no coordination or central counter, and still never collide in practice. They're the standard choice for database primary keys, request IDs, idempotency keys and file names in distributed systems.

Can two random UUIDs collide?

Theoretically yes, practically no: with 122 random bits you'd need to generate about 2.7 × 10¹⁸ UUIDs to reach even a 50% chance of a single collision. If every human on earth generated a million UUIDs, duplicates would still be unlikely. The catch is the randomness source — which is why this tool uses the browser's cryptographically secure generator (crypto.randomUUID), not Math.random().

FAQ

UUID v4 vs v1 vs v7 — which should I use?

v4 is pure randomness — the safe default. v1 embeds a timestamp and MAC address (leaks information, rarely wanted now). v7 is the newer time-ordered variant: random but with a leading timestamp, so database indexes stay append-friendly. If your UUIDs are primary keys in a write-heavy table, consider v7; otherwise v4 is fine.

Are UUIDs with hyphens and without equivalent?

Yes — the hyphens are purely presentational. Some systems (and 32-char column schemas) expect the compact form; toggle "Without hyphens" to get it. Case is also insignificant per the RFC, though lowercase is the canonical form.

Is it safe to use these for database keys?

Yes — that's their most common job. They're generated locally with a CSPRNG and never leave your browser, so no external service knows the IDs you'll use.