I don’t think this feature will be available soon in Thunkable for now. But let’s hope it does. I’d like to show you a work-around to this, which is like -
- create an html file named ‘encode.html’ in (any preferred editor) with this code -
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<script type="text/javascript">
var ThunkableWebviewerExtension = {
postMessage: function (message) {
if (window.ReactNativeWebView) {
window.ReactNativeWebView.postMessage(message);
} else {
window.parent.postMessage(message, '*');
}
},
receiveMessage: function(fxn) {
var callbackFunction = function(event) {
if (typeof fxn === 'function') {
fxn(event.data)
}
};
document.addEventListener('message', callbackFunction, false);
window.addEventListener('message', callbackFunction, false);
}
}
</script>
</head>
<body>
<script type="text/javascript">
var test;
var value;
ThunkableWebviewerExtension.receiveMessage(function(message) {
value = message;
encoded = btoa(value);
ThunkableWebviewerExtension.postMessage(encoded);
});
</script>
</body>
</html>
- upload this file into assets of your project, and add a webviewer to your project.
- set the webviewer’s url in designer properties to ‘encode.html’ (just the file’s name)
- now on the blocks side, use this block to post data to the file - (message = whatever you want to encode)
- and this block to retrieve the encoded value -
Now you have your own Base64 encoder in your app. Let me know if this works for you. 
P.S. don’t get thrown off by the html code, it is a very simple process 