UUID Generator — Free UUID v4 Online

← Circuit CoveThe Creative Island · Island 08

Cryptographically random UUIDs (v4) — generate one or a hundred, copy in one click.

How many? (1–100)

Uppercase?

How to use this tool

1. Set how many UUIDs you want (1–100).
2. Press Generate — each is a fresh version-4 UUID from your device's cryptographic random source.
3. Toggle uppercase for Microsoft-style GUIDs; Copy all grabs the list.

Example

3f8a2c91-7b4d-4e1a-9c5f-2d6e8a01b3c7 — the 4 in the third group marks version 4; the 8/9/a/b first digit of the fourth group marks the variant.

The formula

UUID v4 = 122 random bits + 6 fixed version/variant bits, formatted as 8-4-4-4-12 hex

What the result means

A v4 UUID has about 5.3 × 10³⁶ possible values — generating billions per second for a lifetime still makes collisions practically impossible. That's why databases, distributed systems and session tokens use them instead of incrementing IDs.

Frequently asked questions

Are these UUIDs safe to use in production?

Yes — they come from your browser's cryptographic RNG (crypto.randomUUID with a getRandomValues fallback). For cryptographic keys, use a purpose-built key generator instead.

Can a UUID repeat itself?

Practically no. You would need to generate ~2.7 quintillion IDs for a 50% collision chance — the 'birthday bound' of 122 random bits.

What's the difference between UUID and GUID?

Same idea, one byte longer vs shorter spelling: GUID is Microsoft's name for the RFC 4122 UUID. The uppercase toggle gives you the classic GUID look.

Could two visitors get the same UUID?

Each browser generates independently, but the keyspace is so large that it doesn't matter — this is exactly the property UUIDs were designed for.

More tools from Circuit Cove

Random Token GeneratorOn Safe HarborBase64 Encoder/DecoderEncode or decode textHash GeneratorOn Safe HarborJSON FormatterPretty print JSON

Explore the island world

• Circuit Cove — the island where this tool lives.
• The Main Island — drive the boat, explore the whole world.
• The 90s Kids Island — where most of us started.

Privacy & data: this tool runs entirely in your browser — nothing you type is uploaded, saved or sent anywhere. · Disclaimer: all processing happens locally in your browser — never paste production secrets or private data into any online tool, including this one. · Privacy Policy · Disclaimer