UUID Generator

UUID v4

Version 4 UUIDs are randomly generated. With 122 bits of randomness, the probability of a collision across a trillion UUIDs is negligible. Use them for database primary keys, idempotency keys, file names, and test fixtures.

This page calls crypto.randomUUID(), the Web Crypto API built into every modern browser. That matters: the randomness comes from a cryptographically secure source, not Math.random(). Plenty of copy-paste UUID snippets on the internet get this wrong, and a weakly-seeded UUID is exactly the kind of bug you never notice until two of them collide in production.

How to Use It

One UUID is generated the moment the page loads — most of the time you can just click it and go. Need more? Drag the count slider up to 100 and hit Generate. The two checkboxes reformat what's already on screen: No hyphens collapses each ID to 32 hex characters (handy for systems that reject the dashed format), and Uppercase does what it says. Copy all puts the whole list on your clipboard, one per line, and Download .txt saves it as a file.

Where They Show Up in Real Work

Seeding a test database is the classic case: generate 50 UUIDs, download the file, and paste them into your fixtures so test runs are reproducible. They're also the standard answer for idempotency keys — Stripe and most payment APIs expect a unique key per request so retries don't double-charge anyone. And if you're naming uploaded files, a UUID prefix kills filename collisions without a round-trip to the database.

Keyboard Shortcut

Press Space or Enter anywhere on the page to regenerate. Useful when you just need one UUID quickly.

Click to Copy

Click any UUID in the list to copy it to the clipboard individually. The copied value flashes green as confirmation.

FAQ

Are these UUIDs sent to a server?

No. Everything runs in your browser using the Web Crypto API. There's no network request, no logging, and nothing to intercept — the IDs exist only on your machine.

Can two generated UUIDs ever collide?

Practically, no. You'd need to generate about 2.7 quintillion UUIDs to reach a 50% chance of a single collision. Your database will fail for a hundred other reasons first.

UUID or GUID — is there a difference?

Same thing. GUID is Microsoft's name for it. If a Windows or .NET tool asks for a GUID, paste a UUID from here and it'll work.

Why v4 and not v7?

UUID v7 embeds a timestamp, which makes it sortable — nice for database indexes. But crypto.randomUUID() only produces v4, and for most jobs (keys, tokens, file names) pure randomness is exactly what you want.