UUID generator
Generate version 4 UUIDs from a secure random source.
- Runs in your browser — your text is never sent anywhere
- No sign-up, no quotas, free to use as often as you like
How it works
A UUID is a 128-bit identifier long enough that you can generate one anywhere, at any time, without coordinating with anyone, and be confident nobody else will ever generate the same one.
Version 4 means random
A v4 UUID is random apart from a few bits identifying the version. There are roughly 5.3 times 10 to the 36 of them, so accidental collision is not a practical concern.
Where the randomness comes from
These come from the browser cryptographic random number generator rather than a general-purpose one, so the values are suitable where unpredictability matters as well as uniqueness.
Version 4, as defined in RFC 9562
Every UUID here is version 4: 122 random bits plus fixed version and variant bits, written as 32 hexadecimal digits in five groups. The randomness comes from your browser's cryptographically secure generator (crypto.randomUUID, or crypto.getRandomValues where that is missing). You can make up to 500 at a time.
How unique they are
With 122 random bits you would need to generate around 2.7 billion billion (2.7 × 1018) UUIDs before there was even a 50% chance of a single repeat.
What it does not make
Version 7 UUIDs, which begin with a timestamp so that they sort by creation time, are not generated here.
UUID generator — questions
Are these really unique?
For practical purposes, yes. The space is large enough that collision is not a realistic concern.
Can I generate many at once?
Yes, up to 500 at a time.
Are they generated on a server?
No. They come from your own browser.