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HTML DOM Window atob( ) Method

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The Window atob() method is used for decoding a base-64 encoded string. It is used to decode a string of data which has been encoded using the btoa() method. It returns a string which represents the decoded string. 

Syntax :


Parameters Used :

  • EncodedString : It is a mandatory parameter which specifies the encoded string.

Below program illustrates the Window atob() Method : 

Decoding a string encoded using the btoa() method. 


<!DOCTYPE html>
      Window atob() Method in HTML
        h1 {
            color: green;
        h2 {
            font-family: Impact;
        body {
            text-align: center;
    <h2>Window atob() Method</h2>
      For decoding a base-64 encoded string,
      double click the "Decode Message" button:
    <button ondblclick="decode()">
      Decode Message
    <p id="myDecoding"></p>
        function decode() {
            var original = "GeeksforGeeks";
            var encoded = window.btoa(original);
            var decoded = window.atob(encoded);
            var output = "Encoded String : " 
            + encoded + "<br>" + "Decoded String : "
            + decoded;
            document.getElementById("myDecoding").innerHTML =


After clicking the button:

Supported Browsers: The browser supported by Window atob( ) Method are listed below:

  • Google Chrome 4
  • Edge 12
  • Internet Explorer 10
  • Firefox 1
  • Opera 10.5
  • Safari 3

Last Updated : 15 Jun, 2023
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