How to Generate a NanoID Online: Step-by-Step

To generate a NanoID online, open the ByteTools NanoID Generator, set your ID size (21 by default), optionally edit the alphabet, choose how many IDs you want, and click Generate — every ID is created with crypto-secure randomness right in your browser. Nothing is uploaded or stored, so the IDs are private to you and the tool works offline once loaded.

This tutorial covers each control, what the defaults mean, and how to copy IDs in bulk for your project.

What a NanoID is and why the defaults matter

A NanoID is a compact, URL-safe unique string. The default is 21 characters drawn from a 64-symbol alphabet of letters, digits, underscore and hyphen — the same defaults as the popular nanoid library. That length gives collision resistance comparable to a UUID while being shorter and needing no dashes or special formatting, so it drops cleanly into URLs, slugs and tokens.

Step-by-step: generate your IDs

1. Set the ID size. Leave it at 21 for a general-purpose ID, or shorten it for compact codes and lengthen it for extra collision headroom.
2. Edit the alphabet (optional). The default is URL-safe. Swap it for digits only, lowercase-only, or any character set your keys need.
3. Choose how many. Generate anywhere from 1 to 50 IDs in a single pass.
4. Click Generate. The IDs appear instantly, ready to review.
5. Copy one or the whole batch. Grab a single ID, or copy every ID at once for seeding a table or config.

How the randomness works

Every character comes from your browser's cryptographically secure generator via crypto.getRandomValues. Critically, the tool uses unbiased rejection sampling rather than a naive random-byte-modulo approach. Taking a byte modulo the alphabet size would make some characters slightly more likely than others; rejection sampling masks random bytes and discards out-of-range values so every symbol has exactly equal probability. That keeps the full entropy of your IDs intact — important when they are used as unguessable tokens.

This matters more than it first appears. If some characters appear more often than others, the effective number of possible IDs shrinks, which raises collision odds and makes tokens marginally easier to guess. By discarding out-of-range random values instead of folding them back in, the generator guarantees a perfectly flat distribution across whatever alphabet you choose, whether that is the full 64 symbols or a trimmed digits-only set.

Copying and using your IDs

Once generated, you can copy a single ID with one click or grab the entire batch at once. That batch copy is the fastest way to seed a database table, populate test fixtures, or drop a set of unique keys into a config file. Because the IDs are URL-safe by default, you can paste them straight into routes, filenames or query strings without any escaping. And since everything is computed locally, you can generate sensitive keys on a machine that is offline or air-gapped and trust that nothing was transmitted anywhere.

Try the NanoID Generator — free and 100% in your browser.

FAQ

Is a shorter NanoID safe to use?

It depends on how many IDs you will ever generate. Shorter IDs have a higher collision probability, so keep the default 21 for large-scale or security-sensitive use, and only shrink for low-volume, human-facing codes.

Can I generate many IDs at once?

Yes. Set the count up to 50 and click Generate to produce a whole batch, then copy them all in one click — handy for seeding a database or a test fixture.

Are these IDs suitable for URLs?

Yes. The default alphabet is URL-safe, meaning the characters need no encoding, so the IDs slot directly into paths, query strings and slugs.

Do the IDs get sent to a server?

No. Every ID is generated locally in your browser and nothing is uploaded, logged or stored, so your IDs stay private and the tool works offline.

Related free tools

• UUID Generator — create standard RFC-style UUIDs.
• ULID Generator — sortable, timestamped unique IDs.
• Slug Generator — turn text into clean URL slugs.
• Base32 Encode — encode data into a compact alphabet.

Built by ByteVancer

ByteTools is a free product of ByteVancer, a software and web development studio building web apps, SaaS and custom software. If you need help designing IDs, schemas or a full backend, explore what ByteVancer can build for you.