Encode and Decode a String using Base64 scheme

gistfile1.php

<?php

function base64url_encode($plainText)
{
    $base64 = base64_encode($plainText);
    $base64url = strtr($base64, '+/=', '-_,');

    return $base64url;
}

function base64url_decode($plainText) 
{
    $base64url = strtr($plainText, '-_,', '+/=');
    $base64 = base64_decode($base64url);

    return $base64;
}