base62

Encode & decode strings, bytes, and integers to Base62

Base62 is ideal for URL shortening, creating readable codes, and compact data representation, because it compresses large values into shorter, alphanumeric strings, maximizing space efficiency and readability.

Install

npm install @sindresorhus/base62

Usage

import base62 from '@sindresorhus/base62';

const encodedString = base62.encodeString('Hello world!');
console.log(encodedString);
//=> '28B5ymDkgSU62aA0v'

console.log(base62.decodeString(encodedString));
//=> 'Hello world!'

console.log(base62.encodeString('🦄'));
//=> '95s3vg'

console.log(base62.encodeInteger(1337));
//=> 'LZ'

[!NOTE] The output may differ from other Base62 encoders due to variations in alphabet order and byte encoding.

API

It uses the most common alphabet for Base62: 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz

encodeString(string: string): string

Encodes a string to a Base62 string.

[!CAUTION] The result format is not yet guaranteed to be stable across package versions. Avoid using it for persistent storage.

decodeString(encodedString: string): string

Decodes a Base62 encoded string created with encodeString() back to the original string.

encodeBytes(bytes: Uint8Array): string

Encodes bytes to a Base62 string.

[!CAUTION] The result format is not yet guaranteed to be stable across package versions. Avoid using it for persistent storage.

decodeBytes(encodedString: string): Uint8Array

Decodes a Base62 string created with encodeBytes() back to bytes.

encodeInteger(integer: number): string

Encodes a non-negative integer to a Base62 string.

decodeInteger(encodedString: string): number

Decodes a Base62 string to an integer.

encodeBigInt(integer: bigint): string

Encodes a non-negative bigint to a Base62 string.

decodeBigInt(encodedString: string): bigint

Decodes a Base62 string to a bigint.

Custom alphabets

You can use a custom alphabet by using the Base62 class:

import {Base62} from '@sindresorhus/base62';

// Create instance with custom alphabet
const customBase62 = new Base62({
    alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'
});

console.log(customBase62.encodeInteger(1337));
//=> 'Vj' (different from default 'LZ')

// Or use special characters
const symbolBase62 = new Base62({
    alphabet: '!@#$%^&*()_+-=[]{}|;:,.<>?/~`0123456789ABCDEFGHIJKLMNOPQRSTUVW'
});
console.log(symbolBase62.encodeInteger(42));
//=> 'D'

[!NOTE] The alphabet must be exactly 62 unique characters.

Base62

constructor(options?)

Create a new Base62 encoder/decoder instance.

options

Type: object

alphabet

Type: string\ Default: '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'

Custom alphabet containing exactly 62 unique characters.

The Base62 class has the same methods as the exported functions: encodeString(), decodeString(), encodeBytes(), decodeBytes(), encodeInteger(), decodeInteger(), encodeBigInt(), and decodeBigInt().