QKitBoxUUID v4 generator
Cryptographically random UUIDs (version 4) from your browser's crypto API — no server round trip, no counter to collide.
Generated with crypto.getRandomValues — the same entropy source browsers use for session keys. Suitable for database keys, file names and test fixtures.
How it works
A v4 UUID has 122 random bits (6 bits are fixed by the version/variant markers). The chance of two colliding is so small that systems generate billions without seeing one — which is why v4 is the default identifier for records that must be unique across systems without coordination.
Frequently asked questions
Are UUIDs secret?
No — they're identifiers, not secrets. Anything a user can obtain (in a URL, for example) can be shared. Use them for uniqueness, not authorization.
Why not incrementing numbers?
Sequential IDs leak volume and are enumerable; v4 IDs are unguessable and merge safely between systems.
Written and maintained by Steven Huang · Last reviewed October 29, 2026.