UUID Generator Converter
Generate cryptographically random UUIDs in bulk.
Not needed
Identifiers
About the UUID Generator converter
A UUID is a 128-bit identifier you can generate anywhere without coordinating with a central authority, which is why they are everywhere in distributed systems.
These are generated with the Web Crypto API — the same source your browser uses for TLS — not `Math.random()`. Nothing is requested from a server, so the values never travel anywhere before you use them.
v4 or v7?
Version 4 is 122 bits of randomness. It is the right default and the one almost everyone means by "a UUID". Collisions are, for practical purposes, impossible.
Version 7 puts a millisecond timestamp in the leading bits, so IDs sort chronologically. That matters a great deal for database primary keys: random v4 keys scatter inserts across a B-tree index, while v7 keys append, keeping the index compact and writes fast.
Nano ID is not a UUID at all — it is a 21-character URL-safe string with comparable collision resistance and a much friendlier length for URLs.
Should you use a UUID as a primary key?
They avoid the coordination and enumeration problems of sequential integers, at the cost of 16 bytes per row and worse index locality. If you go that way, prefer v7, and store them as a native UUID type rather than as text.
Frequently asked questions
Can two UUIDs ever collide?
In theory. In practice you would need to generate roughly a billion v4 UUIDs per second for a century to reach a 50% chance of a single collision.
Are these safe to use as secrets or session tokens?
v4 UUIDs come from a cryptographic source, but they are usually logged and shared as identifiers. Use a dedicated token with more entropy for anything that grants access.
Why do I get the same output each time I press Convert?
You should not — each press generates fresh values. If they look similar, check that you are on v7, where the leading timestamp bits are nearly identical between adjacent calls.