UUID Generator
Cryptographically random version 4 UUIDs, generated in your browser.
Runs entirely in your browser — nothing you paste is sent to our servers.
What this tool does
Properly random
From crypto.randomUUID, backed by the platform CSPRNG — not a timestamp, counter or Math.random.
Bulk generation
Up to 100 at a time, copyable individually or as one newline-separated block.
Valid v4 format
Correct version and variant bits, so they pass strict UUID validation.
Never leaves your browser
No server sees an identifier you are about to use.
Frequently asked questions
Are these UUIDs cryptographically random?
Yes. They come from crypto.randomUUID, or crypto.getRandomValues where that is unavailable - both backed by the platform CSPRNG. They are not derived from a timestamp, a counter or Math.random.
What is a version 4 UUID?
A UUID with 122 random bits and 6 fixed version and variant bits. The 13th hex digit is always 4 and the 17th is one of 8, 9, a or b, which is how you can identify one by eye.
Could I ever get a duplicate?
In practice, no. With 122 random bits you would need to generate billions per second for a century before collision probability became worth thinking about. If you need ordering as well as uniqueness, look at UUIDv7 or ULID instead.
Are UUIDs safe to expose in URLs?
A v4 UUID is unguessable, so it does not leak information the way a sequential id does. That makes it fine as a public identifier, but it is not an access control - always still check authorisation.
Is generation done on your server?
No. Every UUID is generated locally in your browser, so no server ever sees an identifier you intend to use.
Monitor it, don't just check it
One-off checks catch what is broken today. CertNotify watches your certificates, domains, DNS and code continuously and tells you before something breaks.