# base-x

> Fast base encoding / decoding of any given alphabet

Latest version **5.0.1** (published 2025-03-08) · MIT license · 0 weekly downloads

## Install

```sh
npm install base-x
pnpm add base-x
yarn add base-x
bun add base-x
```

## Health

**Score 50/100 (C)** — status: stable.

Positive: has types; esm support; no vulnerabilities; high quality score.

Warnings: low downloads.

Negative: stale.

## Facts

| | |
|---|---|
| Version | 5.0.1 |
| Published | 2025-03-08 |
| First published | 2015-05-19 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | ESM + CommonJS |
| Dependencies | 0 |
| Unpacked size | 14 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 338 |
| Author | Daniel Cousens |
| Maintainers | fanatid, jprichardson, junderw |
| Keywords | base-x, base58, base62, base64, crypto, crytography, decode, decoding, encode, encoding |

## Links

- npm: https://www.npmjs.com/package/base-x
- Repository: https://github.com/cryptocoinjs/base-x
- Issues: https://github.com/cryptocoinjs/base-x/issues
- npm.io page: https://npm.io/package/base-x

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## Recent versions

- 5.0.1 (latest) — 2025-03-08
- 3.0.10 (bp) — 2024-07-04
- 3.0.11 — 2025-03-08
- 4.0.1 — 2025-03-08
- 5.0.0 — 2024-06-22
- 4.0.0 — 2022-02-17
- 3.0.9 — 2021-10-22
- 3.0.8 — 2020-02-25
- 3.0.7 — 2019-09-05
- 3.0.6 — 2019-07-03
- 3.0.5 — 2018-11-02
- 3.0.4 — 2017-12-28
- 3.0.3 — 2017-12-05
- 3.0.2 — 2017-05-24
- 2.0.6 — 2017-05-24
- … 14 more at https://npm.io/package/base-x/versions

## README

# base-x

[![NPM Package](https://img.shields.io/npm/v/base-x.svg?style=flat-square)](https://www.npmjs.org/package/base-x)
[![Build Status](https://img.shields.io/travis/cryptocoinjs/base-x.svg?branch=master&style=flat-square)](https://travis-ci.org/cryptocoinjs/base-x)

[![js-standard-style](https://cdn.rawgit.com/feross/standard/master/badge.svg)](https://github.com/feross/standard)

Fast base encoding / decoding of any given alphabet using bitcoin style leading
zero compression.

**WARNING:** This module is **NOT RFC3548** compliant,  it cannot be used for base16 (hex), base32, or base64 encoding in a standards compliant manner. 

## Example

Base58

``` javascript
var BASE58 = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
import basex from 'base-x'
var bs58 = basex(BASE58)

var decoded = bs58.decode('5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr')

console.log(decoded)
// => Uint8Array(33) [
//   128, 237, 219, 220,  17, 104, 241, 218,
//   234, 219, 211, 228,  76,  30,  63, 143,
//    90,  40,  76,  32,  41, 247, 138, 210,
//   106, 249, 133, 131, 164, 153, 222,  91,
//    25
// ]

console.log(bs58.encode(decoded))
// => 5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr
```

### Alphabets

See below for a list of commonly recognized alphabets, and their respective base.

Base | Alphabet
------------- | -------------
2 | `01`
8 | `01234567`
11 | `0123456789a`
16 | `0123456789abcdef`
32 | `0123456789ABCDEFGHJKMNPQRSTVWXYZ`
32 | `ybndrfg8ejkmcpqxot1uwisza345h769` (z-base-32)
36 | `0123456789abcdefghijklmnopqrstuvwxyz`
58 | `123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz`
62 | `0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`
64 | `ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/`
67 | `ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.!~`


## How it works

It encodes octet arrays by doing long divisions on all significant digits in the
array, creating a representation of that number in the new base. Then for every
leading zero in the input (not significant as a number) it will encode as a
single leader character. This is the first in the alphabet and will decode as 8
bits. The other characters depend upon the base. For example, a base58 alphabet
packs roughly 5.858 bits per character.

This means the encoded string 000f (using a base16, 0-f alphabet) will actually decode
to 4 bytes unlike a canonical hex encoding which uniformly packs 4 bits into each
character.

While unusual, this does mean that no padding is required and it works for bases
like 43. 


## LICENSE [MIT](LICENSE)
A direct derivation of the base58 implementation from [`bitcoin/bitcoin`](https://github.com/bitcoin/bitcoin/blob/f1e2f2a85962c1664e4e55471061af0eaa798d40/src/base58.cpp),  generalized for variable length alphabets.

---
_Source: https://npm.io/package/base-x · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._