UUID Generator
Generate universally unique identifiers in bulk. Choose random v4 or time-ordered v7 UUIDs, generated locally with your browser's cryptographic random number generator.
UUID v4 vs v7
v4 UUIDs are 122 bits of randomness - ideal when you just need a unique ID. v7 UUIDs start with a 48-bit millisecond timestamp followed by random bits, so they sort by creation time. That makes them much friendlier as database primary keys because inserts stay clustered instead of scattering across the index.
Are UUIDs really unique?
The chance of generating two identical v4 UUIDs is astronomically small - you would need to generate about a billion per second for decades to have a meaningful chance of a single collision.
Frequently asked questions
What is the difference between a UUID and a GUID?
They are the same thing. GUID is the term used mainly in Microsoft ecosystems; UUID is the standard name (RFC 9562).
Should I use UUID v4 or v7 as a database key?
v7 is generally better for database primary keys because it is roughly time-ordered, which reduces index fragmentation. v4 is fine for identifiers where ordering does not matter.
Are these UUIDs generated securely?
Yes. They use crypto.getRandomValues() from the Web Crypto API, generated locally in your browser.
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