Free Online UUID Generator (v4)

You need an ID that's guaranteed not to collide with any other ID, anywhere, without checking a database first. That's what a UUID is for — a 128-bit value like 550e8400-e29b-41d4-a716-446655440000that's effectively unique across every system that might ever generate one, with no coordination required. A UUID generator gives you one (or a batch) instantly.

Why UUIDs instead of auto-incrementing numbers

An auto-incrementing integer ID only works within one database, one table. The moment you have multiple services, offline clients, or merged datasets, two records can end up with the same numeric ID and no way to tell them apart. UUIDs sidestep the whole problem — they're generated independently, with random or pseudo-random values large enough that a collision is astronomically unlikely, so any two systems can generate IDs in isolation and never clash.

What "v4" means

UUIDs come in several versions with different generation rules; the one you almost always want is v4 — generated from random bytes, per RFC 4122. It's the default in virtually every UUID library, and it's what this tool generates, using your browser's crypto API for the randomness rather than a weaker pseudo-random source.

Where UUIDs actually get used

• Primary keys for database records, especially in distributed systems with multiple writers.
• Session tokens and API request IDs, for tracing a single request through logs across services.
• Idempotency keys — attaching a UUID to a request so retrying it safely doesn't create a duplicate.
• File and object identifiers in storage systems where filename collisions would be a real problem.

How to generate UUIDs

1. Open the UUID Generator.
2. Click generate — you get a fresh v4 UUID instantly.
3. Generate as many as you need; each one is independently random.
4. Copy one or all of them into your code, database, or config.

Generation happens entirely in your browser using the Web Crypto API, so there's no server round trip and no risk of two people generating the same value at the same moment.

Related developer tools

If you need a shorter, deterministic fingerprint instead of a random identifier — say, to detect whether two files are identical — that's a different job for the Hash Generator. And if the UUID is going into a token payload, the JWT Decoder lets you check exactly what claims are already in there.