Nano ID Generator

How to use

1. 1Pick an alphabet: keep the Nano ID default (64 URL-safe characters), choose a preset such as lowercase plus numbers, no look-alikes, or hex, or select Custom alphabet to type your own.
2. 2Set the ID length (size). The Nano ID default is 21; the entropy readout shows the bits per ID so you can tell when an ID is strong enough or too short.
3. 3Set how many IDs to create, then click Generate Nano IDs to produce a fresh batch.
4. 4Copy a single ID with its Copy button, or use Copy all to grab the whole batch as one list.
5. 5Enter your expected generation rate and unit to see how long you can run before a roughly one percent collision chance, and shorten or lengthen the size accordingly.

About this tool

Nano ID Generator creates Nano IDs in your browser using the exact algorithm from the reference library (ai/nanoid), so the output is distributed the same way the real package distributes it. A Nano ID is a compact, URL-safe, collision-resistant string ID, and it has become a popular alternative to UUID for database keys, public record identifiers, short links, file names, and React keys. The key difference from a UUID is that a Nano ID has no fixed length and no version or layout bits: you choose the alphabet and the size, and its strength comes entirely from those two numbers. The default Nano ID is 21 characters drawn from a 64 character URL-safe alphabet (A to Z, a to z, 0 to 9, plus underscore and dash), which carries about 126 bits of randomness, essentially the same as a random UUID, in fewer characters and with nothing that needs escaping in a URL. This tool generates one ID or a batch at once, and lets you switch the alphabet between the Nano ID default, lowercase plus numbers, alphanumeric, hexadecimal, digits only, a no-look-alikes set that drops easily confused characters like 0, O, 1, and I, or a fully custom alphabet of your own. Under the hood it reproduces the library's two defining formulas: the bitmask is built as (2 left-shift (31 minus Math.clz32 of ((length minus 1) bitwise-or 1))) minus 1, the smallest power-of-two-minus-one that can index your alphabet, and each random byte from crypto.getRandomValues is reduced with byte bitwise-and mask. Bytes whose masked value falls outside the alphabet are discarded, which is what keeps every character equally likely and avoids the modulo bias you would get from a naive remainder. Random bytes are drawn in batches sized by ceil(1.6 times mask times size divided by length), the same slight over-allocation the library uses so one batch usually fills the ID even after rejections. Beyond generation, the tool answers the question every Nano ID adopter actually asks: is my size big enough, and could I safely make it shorter? It estimates how long you can keep generating IDs at a chosen rate, per second, per hour, or per day, before there is roughly a one percent chance of a single collision, using the birthday approximation n is approximately the square root of (2 times N times the natural log of (1 divided by (1 minus p))), where N is the ID space (alphabet size raised to the ID length) and p is one percent. A live entropy readout shows the bits per character and the total bits per ID, with a rough strength label so you can see at a glance when a short ID is too weak or when a long one is overkill. The collision figure is a planning guide rather than a guarantee, and it assumes a good random source, which the browser crypto API provides. Everything, the alphabet, the options, and every generated ID, is computed locally in your browser and is never uploaded, never logged, and never leaves your device.

Free to use. Works in your browser. No signup, no login.