NanoID Generator

About NanoID

NanoID is a unique identifier generator created in 2017 by Andrey Sitnik, the same developer who created PostCSS and Autoprefixer. It was designed in response to a specific frustration: UUIDs are 36 characters long, contain hyphens, and are awkward in URLs. NanoID provides a more compact, URL-safe alternative with comparable uniqueness guarantees.

A default NanoID is 21 characters drawn from a 64-character alphabet (A-Za-z0-9_-), giving roughly 126 bits of entropy. The alphabet is URL-safe by design — no characters need escaping when included in a path or query string. The default size offers collision resistance comparable to UUID v4 (a 1% chance of collision requires generating roughly 4 × 10¹⁸ IDs).

The library has gained significant adoption in JavaScript and TypeScript ecosystems, particularly through ORMs like Prisma, which uses NanoID as a built-in option for primary key generation. It's also available as a library in Python, Go, Rust, .NET, Java, and most other major languages — this site uses the canonical Nanoid .NET port.

When to use NanoID

NanoID is a good fit when:

• You need URL-friendly identifiers. No hyphens, no need for escaping, shorter than UUIDs while still highly collision-resistant.
• You want configurable length or alphabet. NanoID accepts custom alphabets and lengths, letting you trade collision resistance against compactness for your specific use case.
• Your ecosystem already uses NanoID. If you're working in a JavaScript/TypeScript project, NanoID is often the path of least resistance and fits naturally with the surrounding tooling.

A UUID may be the better choice when:

• You need ecosystem interoperability. UUIDs have universal support across databases, frameworks, and protocols. NanoID requires explicit library use.
• You want a time-ordered identifier. NanoID is fully random with no embedded timestamp. For time-sortable IDs, use UUID v7 or ULID.
• You're storing IDs as a native database type. Most databases have a native UUID type with optimised storage. NanoIDs are stored as strings, which costs marginally more space and is slower to compare.

Read the full comparison: NanoID vs UUID — which should you use? It works through size, encoding, ecosystem support, and the cases where each is the right choice. NanoID is also the go-to when a distributed system needs a short, URL-facing identifier rather than a sortable one; generating IDs in distributed systems places it alongside UUID v7, ULID, and Snowflake.

Choosing length and alphabet

The default 21 characters with the URL-safe alphabet is appropriate for most uses. Reasons you might deviate:

• Shorter (10–16 characters) for short-lived tokens, URL shorteners, or contexts where size is critical and collision risk over your expected volume is acceptable. The official NanoID collision calculator helps you pick a length to match your scale.
• Longer (32+ characters) for very high-volume systems or for stronger guessability resistance. With a longer ID, an attacker brute-forcing the namespace must search a correspondingly larger space.
• Alphanumeric only (no _ or -) for contexts where URL-safety isn't the priority but readability is — for example, IDs that might be transcribed by hand.
• Numeric only for human-friendly IDs in contexts like phone PINs or short codes (though for such uses, the additional collision risk and lack of typo-resistance often make a different approach better).

Implementation considerations

Use a cryptographic random source. Reference NanoID implementations use Web Crypto in browsers, crypto in Node.js, and RandomNumberGenerator in .NET — all cryptographically secure. If you implement NanoID yourself, do not use Math.random() or equivalent non-CSPRNG sources. For security-sensitive identifiers (tokens, keys), the random source matters as much as the alphabet and length.

Storage as strings. NanoIDs don't have a compact binary representation in the way UUIDs do. Stored as a database string they take the full length plus any length-prefix overhead. For databases with significant ID storage volume, this can be a measurable cost worth considering.

Generating in code

import { nanoid } from 'nanoid'
const id = nanoid() // 21-char URL-safe

using NanoidDotNet;
var id = Nanoid.Generate();
// Custom alphabet + length:
var pin = Nanoid.Generate("0123456789", 6);

from nanoid import generate
id = generate()

FAQ