NanoID Generator

NanoID is a tiny, secure, URL-friendly unique string ID. By default it is 21 characters long using a 64-symbol alphabet of A-Z, a-z, 0-9, plus '-' and '_', so it is safe to drop into URLs, filenames and database keys.

A v4 UUID is a fixed 36-character format with 122 bits of randomness. A default NanoID is shorter at 21 characters with about 126 bits, so it is more compact for the same collision safety. Use UUID when a standard format is required, and NanoID when you want shorter, cleaner IDs.

Practically, yes. A 21-character default NanoID has roughly 126 bits of entropy, so the odds of two colliding are vanishingly small even at billions of IDs. This tool also keeps every ID in a batch distinct.

Each ID is built from your browser's cryptographic random source, crypto.getRandomValues. To avoid bias when the alphabet size is not a power of two, the tool uses rejection sampling with a bitmask, the same technique as the NanoID library, so every symbol is equally likely.

Yes. Set any size from 1 to 256 characters and supply any alphabet from 2 to 256 symbols. Built-in presets cover URL-safe, alphanumeric, lowercase, numbers and hex. A shorter alphabet or size means fewer bits of entropy, which the collision note reflects.

No. Every NanoID is generated locally in your browser, so the values never leave your device. Refresh the page and they are gone.