Free UUID Generator (v4 and v1)
Generate universally unique identifiers using your browser's cryptographic random source. Bulk generation supported.
Frequently Asked Questions
What is the difference between UUID v4 and v1?
v4 UUIDs are generated from 122 bits of random data and are the standard choice for most applications. v1 UUIDs embed the current timestamp, so they sort roughly by creation time — useful for database keys where insertion order matters — but they reveal when they were created.
Are these UUIDs really unique?
Practically, yes. The probability of two random v4 UUIDs colliding is so small (about 1 in 2¹²²) that you would need to generate billions of UUIDs per second for decades before a duplicate becomes likely.
Is it safe to use these in production?
Yes. v4 UUIDs are generated with the Web Crypto API (crypto.randomUUID / crypto.getRandomValues), which is cryptographically secure. The v1 node identifier is randomized per the RFC 4122 privacy recommendation rather than using your real MAC address.
Are the UUIDs generated on a server?
No. All generation happens locally in your browser, so the identifiers are never transmitted or logged anywhere.