UUID Generator (v4 GUID)
Generate cryptographically secure UUID v4 identifiers. Click to copy each UUID.
A UUID (Universally Unique Identifier) is a 128-bit identifier that’s practically guaranteed to be unique without any central authority — perfect for database keys, request IDs, file names, and distributed systems. This tool generates random version-4 UUIDs using the Web Crypto API and supports standard, uppercase, and no-hyphen formats.
How to generate a UUID
- Pick a format: standard lowercase, uppercase, or no hyphens.
- Choose how many UUIDs you need.
- Click Generate — new random UUIDs appear instantly.
- Copy one with its button, or Copy All to grab the whole list.
What a v4 UUID looks like
The structure is 8-4-4-4-12 hex digits. In a v4 UUID the third group starts with a 4 (the version) — everything else is pure randomness, giving 122 random bits: you could generate a billion UUIDs per second for a century and stay unlikely to collide.
3f8a2c1e-7b4d-4e9a-9c2f-1a5b8d3e7c4fFrequently asked questions
UUID vs GUID — what’s the difference?
None, practically. GUID is Microsoft’s name for the same concept; UUID is the standard term.
Are generated UUIDs safe to use as database keys?
Yes for uniqueness, with a caveat: fully random v4 UUIDs scatter across indexes, which can hurt insert performance at very large scale. Some teams prefer ordered UUIDs (v7) for hot indexes.
Can two UUIDs collide?
Astronomically unlikely — 122 random bits means you’d need to generate trillions before collision odds become worth thinking about.
Is generation really random?
Yes — crypto.getRandomValues from the Web Crypto API, generated locally.