---
title: atob
summary: The atob() function decodes a string of data which has been encoded using Base64 encoding.
url: https://www.fastly.com/documentation/reference/compute/sdks/javascript/js-compute/globals/fn.atob/
---

**Kind:** Function  
**Module:** [globals](https://www.fastly.com/documentation/reference/compute/sdks/javascript/js-compute/globals/)  
**Package:** @fastly/js-compute 4.0.1  
**Source:** https://github.com/fastly/js-compute-runtime/blob/70cf30af4e657879b2d1e7eafab880e39e3a3f7d/types/globals.d.ts#L2108

```javascript
atob(data: string): string
```

The atob() function decodes a string of data which has been encoded using Base64 encoding.

**See also**

- [atob on MDN](https://developer.mozilla.org/en-US/docs/Web/API/atob)

**Parameters**

- `data`: `string` — A binary string (i.e., a string in which each character in the string is treated as a byte of binary data) containing base64-encoded data.

**Returns**

`string`

An ASCII string containing decoded data from `data`.