# Encoding and decoding Base64  strings in Node.js

By Atta Ur Rehman Shah (https://attacomsian.com/about). Published Apr 7, 2020, updated Oct 1, 2022. Topics: Node.js.
Canonical URL: https://attacomsian.com/blog/nodejs-base64-encode-decode

> A detailed guide to learn how to perform Base64 encoding and decoding in a Node.js application.

In an earlier article, we looked at how to Base64 encode and decode a string in [Java](https://attacomsian.com/blog/base64-encode-decode-java) and [JavaScript](https://attacomsian.com/blog/javascript-base64-encode-decode). Today, you'll learn how to do the Base64 encoding and decoding in a Node.js application.

Unfortunately, Node.js doesn't support standard JavaScript functions like `atob()` and `btoa()` for Base64 encoding. These methods are part of the `window` object and are only available in the browser.

Luckily, Node.js provides a native [`Buffer`](https://nodejs.org/docs/latest/api/buffer.html) module that can be used to perform Base64 encoding and decoding. `Buffer` is available as a global object, and you don't need to explicitly require this module in your application.

Internally, `Buffer` represents binary data in the form of a sequence of bytes. The `Buffer` object provides several methods to perform different encoding and decoding conversions. This includes to and from UTF-8, UCS2, Base64, ASCII, UTF-16, and even the HEX encoding scheme.

Let us look at the below examples that explain how to use the `Buffer` object to perform Base64 encoding and decoding in a Node.js application.

## Base64 Encoding

To convert a string into a Base64 encoded string, we first create a buffer from the given string using the `Buffer.from()` method. This method takes two parameters, a plain-text string, and the character encoding, and creates a buffer or binary data array for the given encoding. If no character encoding is specified, UTF-8 will be used as the default.

Here is an example:

```javascript
// plain-text string
const str = 'Base64 Encoding in Node.js';

// create a buffer
const buff = Buffer.from(str, 'utf-8');

// decode buffer as Base64
const base64 = buff.toString('base64');

// print Base64 string
console.log(base64);

// QmFzZTY0IEVuY29kaW5nIGluIE5vZGUuanM=
```

In the above example, we created a buffer from the string and used the `toString()` method to decode the buffer as a Base64 string. The second parameter in `Buffer.from()` is optional when dealing with plain-text (UTF-8) strings.

## Base64 Decoding

The Base64 decoding process is very much similar to the encoding process. All you need to do is create a buffer from the Base64 encoding string by using `base64` as the second parameter to `Buffer.from()` and then decode it to the UTF-8 string by using the `toString()` method.

Here is what it looks like:

```javascript
// Base64 encoded string
const base64 = 'QmFzZTY0IEVuY29kaW5nIGluIE5vZGUuanM=';

// create a buffer
const buff = Buffer.from(base64, 'base64');

// decode buffer as UTF-8
const str = buff.toString('utf-8');

// print normal string
console.log(str);

// Base64 Encoding in Node.js
```

## Conclusion

That's all for Base64 encoding and decoding in Node.js. We looked at how to use the native `Buffer` module to perform the Base64 encoding and decoding in a Node.js application. The `Buffer` object is not just limited to Base64 conversions. You can even use it to perform ASCII, HEX, UTF-16, and UCS2 encodings and decodings.

If you want to learn more about Base64 conversions in JavaScript, read [this guide](https://attacomsian.com/blog/javascript-base64-encode-decode).