# js-base64 > Yet another Base64 transcoder in pure-JS Latest version **3.9.3** (published 2026-08-17) · BSD-3-Clause license · 0 weekly downloads ## Install ```sh npm install js-base64 pnpm add js-base64 yarn add js-base64 bun add js-base64 ``` ## Health **Score 70/100 (B)** — status: active. Positive: has types; esm support; no vulnerabilities; recently updated; high maintenance score; high quality score. Warnings: low downloads. ## Facts | | | |---|---| | Version | 3.9.3 | | Published | 2026-08-17 | | First published | 2013-04-06 | | Weekly downloads | 0 | | License | BSD-3-Clause | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Dependencies | 0 | | Unpacked size | 37.2 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 4361 | | Author | Dan Kogai | | Maintainers | dankogai | | Keywords | base64, binary | ## Links - npm: https://www.npmjs.com/package/js-base64 - Repository: https://github.com/dankogai/js-base64 - Homepage: https://github.com/dankogai/js-base64#readme - Issues: https://github.com/dankogai/js-base64/issues - npm.io page: https://npm.io/package/js-base64 ## Alternatives - [flatbuffers](https://npm.io/package/flatbuffers.md) — 6.0M weekly downloads - [jwt-simple](https://npm.io/package/jwt-simple.md) — 259.5K weekly downloads - [@exodus/patch-broken-hermes-typed-arrays](https://npm.io/package/@exodus/patch-broken-hermes-typed-arrays.md) — 28.5K weekly downloads - [@native-to-anchor/buffer-layout](https://npm.io/package/@native-to-anchor/buffer-layout.md) — 12.2K weekly downloads - [binary-parser-encoder](https://npm.io/package/binary-parser-encoder.md) — 5.3K weekly downloads ## Recent versions - 3.9.3 (latest) — 2026-08-17 - 3.9.2 — 2026-07-27 - 3.9.1 — 2026-07-15 - 3.9.0 — 2026-07-14 - 3.8.1 — 2026-07-09 - 3.8.0 — 2026-06-25 - 3.7.8 — 2025-08-11 - 3.7.7 — 2024-02-21 - 3.7.6 — 2024-01-20 - 3.7.5 — 2023-02-08 - 3.7.4 — 2023-01-08 - 3.7.3 — 2022-11-17 - 3.7.2 — 2021-09-22 - 3.7.1 — 2021-09-14 - 3.7.0 — 2021-09-08 - … 60 more at https://npm.io/package/js-base64/versions ## README [![CI via GitHub Actions](https://github.com/dankogai/js-base64/actions/workflows/node.js.yml/badge.svg)](https://github.com/dankogai/js-base64/actions/workflows/node.js.yml) [![CI on bun](https://github.com/dankogai/js-base64/actions/workflows/bun.yml/badge.svg)](https://github.com/dankogai/js-base64/actions/workflows/bun.yml) # base64.js Yet another [Base64] transcoder. [Base64]: http://en.wikipedia.org/wiki/Base64 ## Install ```shell $ npm install --save js-base64 ``` ## Usage ### In Browser Locally… ```html ``` … or Directly from CDN. In which case you don't even need to install. ```html ``` This good old way loads `Base64` in the global context (`window`). Though `Base64.noConflict()` is made available, you should consider using ES6 Module to avoid tainting `window`. ### As an ES6 Module locally… ```javascript import { Base64 } from 'js-base64'; ``` ```javascript // or if you prefer no Base64 namespace import { encode, decode } from 'js-base64'; ``` or even remotely. ```html ``` ```html ``` ### node.js (commonjs) ```javascript const {Base64} = require('js-base64'); ``` Unlike the case above, the global context is no longer modified. You can also use [esm] to `import` instead of `require`. [esm]: https://github.com/standard-things/esm ```javascript require=require('esm')(module); import {Base64} from 'js-base64'; ``` ## SYNOPSIS ```javascript let latin = 'dankogai'; let utf8 = '小飼弾' let u8s = new Uint8Array([100,97,110,107,111,103,97,105]); Base64.encode(latin); // ZGFua29nYWk= Base64.encode(latin, true); // ZGFua29nYWk skips padding Base64.encodeURI(latin); // ZGFua29nYWk Base64.btoa(latin); // ZGFua29nYWk= Base64.btoa(utf8); // raises exception Base64.fromUint8Array(u8s); // ZGFua29nYWk= Base64.fromUint8Array(u8s, true); // ZGFua29nYW which is URI safe Base64.encode(utf8); // 5bCP6aO85by+ Base64.encode(utf8, true) // 5bCP6aO85by- Base64.encodeURI(utf8); // 5bCP6aO85by- ``` ```javascript Base64.decode( 'ZGFua29nYWk=');// dankogai Base64.decode( 'ZGFua29nYWk'); // dankogai Base64.atob( 'ZGFua29nYWk=');// dankogai Base64.atob( '5bCP6aO85by+');// '小飼弾' which is nonsense Base64.toUint8Array('ZGFua29nYWk=');// u8s above Base64.decode( '5bCP6aO85by+');// 小飼弾 // note .decodeURI() is unnecessary since it accepts both flavors Base64.decode( '5bCP6aO85by-');// 小飼弾 ``` ```javascript Base64.isValid(0); // false: 0 is not string Base64.isValid(''); // true: a valid Base64-encoded empty byte Base64.isValid('ZA=='); // true: a valid Base64-encoded 'd' Base64.isValid('Z A='); // true: whitespaces are okay Base64.isValid('ZA'); // true: padding ='s can be omitted Base64.isValid('++'); // true: can be non URL-safe Base64.isValid('--'); // true: or URL-safe Base64.isValid('+-'); // false: can't mix both ``` ### Built-in Extensions By default `Base64` leaves built-in prototypes untouched. But you can extend them as below. ```javascript // you have to explicitly extend String.prototype Base64.extendString(); // once extended, you can do the following 'dankogai'.toBase64(); // ZGFua29nYWk= '小飼弾'.toBase64(); // 5bCP6aO85by+ '小飼弾'.toBase64(true); // 5bCP6aO85by- '小飼弾'.toBase64URI(); // 5bCP6aO85by- an alias of .toBase64(true) '小飼弾'.toBase64URL(); // 5bCP6aO85by- an alias of .toBase64URI() 'ZGFua29nYWk='.fromBase64(); // dankogai '5bCP6aO85by+'.fromBase64(); // 小飼弾 '5bCP6aO85by-'.fromBase64(); // 小飼弾 '5bCP6aO85by-'.toUint8Array();// u8s above ``` ```javascript // you have to explicitly extend Uint8Array.prototype Base64.extendUint8Array(); // once extended, you can do the following u8s.toBase64(); // 'ZGFua29nYWk=' u8s.toBase64URI(); // 'ZGFua29nYWk' u8s.toBase64URL(); // 'ZGFua29nYWk' an alias of .toBase64URI() ``` ```javascript // extend all at once Base64.extendBuiltins() ``` ## `.decode()` vs `.atob` (and `.encode()` vs `btoa()`) Suppose you have: ``` var pngBase64 = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNkYAAAAAYAAjCB0C8AAAAASUVORK5CYII="; ``` Which is a Base64-encoded 1x1 transparent PNG, **DO NOT USE** `Base64.decode(pngBase64)`.  Use `Base64.atob(pngBase64)` instead.  `Base64.decode()` decodes to UTF-8 string while `Base64.atob()` decodes to bytes, which is compatible to browser built-in `atob()` (Which is absent in node.js).  The same rule applies to the opposite direction. Or even better, `Base64.toUint8Array(pngBase64)`. ## Brief History * Since version 3.3 it is written in TypeScript. Both `base64.mjs` and `base64.js` are compiled from `base64.ts` via [Rollup](https://rollupjs.org). * Since version 3.7 `base64.js` is ES5-compatible again (hence IE11-compatible). * Since 3.0 `js-base64` switch to ES2015 module so it is no longer compatible with legacy browsers like IE (see above) --- _Source: https://npm.io/package/js-base64 · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._