Free UUID Generator Guide — UUID v4, v7 Explained

UUIDs (Universally Unique Identifiers) are 128-bit identifiers that don't need a central authority to issue. They're the standard for database primary keys in distributed systems, API request IDs, and fixture data. AHX's free UUID generator produces cryptographically random v4 and time-sortable v7 UUIDs in your browser.

UUID v4 vs v7 — which to use?

UUID v4 is fully random. Use it when you don't care about sort order — anonymous tokens, session IDs, fixture data. UUID v7 (RFC 9562, 2024) embeds a millisecond timestamp in the high bits, so v7 UUIDs sort chronologically. Use v7 for database primary keys — it keeps B-tree indexes balanced and makes time-range queries fast.

How many UUIDs do I need?

For batch generation, AHX supports up to 1,000 UUIDs at once. Common use cases: seeding test databases, generating fixture data, pre-allocating IDs for batch inserts.

Collision risk

UUID v4 has 122 bits of randomness. The probability of a collision in 103 trillion UUIDs is 50%. For comparison: if you generated 1 billion UUIDs per second for 85 years, you'd have a 50% chance of one collision. In practice: never worry about v4 collisions.

Are UUIDs generated in the browser safe?

Yes. AHX uses `crypto.getRandomValues()` — the Web Crypto API — which pulls from the OS CSPRNG. This is the same primitive Node.js uses server-side. Your UUIDs are as random as anything you'd get from a server.