UUID Generator

Random UUID v4 generation with batch support

Count:

💡 First button copies UUID with dashes, second button copies plain hex without dashes.

About this tool

A UUID (Universally Unique Identifier) is a 128-bit value used as a unique ID without coordinating with a central authority. The most common variant — UUID v4 — is generated entirely from random bits, giving 122 bits of entropy and a collision probability so low it can be treated as zero in practice.

This generator uses the browser's crypto-strength random source (crypto.getRandomValues) so the values are suitable for production use as primary keys, request IDs, or any unique identifier. Batch generation, uppercase output, and a compact 16-char form are supported.

How to use

Generate UUIDs

Pick the length: standard 36-char UUID (with dashes) or short 16-char form.
Optionally toggle Uppercase if your downstream system expects A-F instead of a-f.
Click Generate. Copy a single UUID with the icon next to it, or Copy All for a newline-separated batch.

Examples

Standard UUID v4

Input

(click Generate)

Output

f47ac10b-58cc-4372-a567-0e02b2c3d479

Batch of 3 (uppercase)

Input

Length: 32, Uppercase: on, Count: 3

Output

B7E2C8D1-4A3F-4C9E-9F1A-D8E5B6C7A2F0
3D9F1E2A-7B4C-4F8E-A1D2-E3F4B5C6D7E8
9A1B2C3D-4E5F-4061-8071-829304A5B6C7

Frequently asked questions

What's the chance of two v4 UUIDs colliding?

Negligible. You'd need to generate roughly 2.71 quintillion UUIDs to have a 50% chance of one collision (the birthday bound on 122 random bits). For comparison, that's more than every grain of sand on Earth.

v4 vs v1 vs v7 — which should I use?

v4 (random) for general use. v1 (timestamp + MAC) leaks the host MAC address and isn't recommended. v7 is a newer time-ordered variant that sorts naturally — great for database primary keys where index locality matters. This tool currently emits v4.

Are these UUIDs cryptographically secure?

Yes. We use crypto.getRandomValues, which is backed by the OS CSPRNG. They're suitable for security-sensitive identifiers like session tokens, though dedicated token APIs (longer, opaque) are usually a better fit there.

Is the short 16-char form still a UUID?

No — it's a 64-bit random hex string we provide for convenience when you don't need full UUID guarantees (e.g., short URLs, idempotency keys for low-volume APIs). Collision risk is much higher than v4 but still practical for most personal use.

Should I generate UUIDs on the client or the server?

Either works. Client-side generation lets you create an ID before the round-trip (useful for offline-first apps and idempotency). Server-side keeps generation logic centralized. The UUIDs themselves are identical in either case.