1. Go to this page and download the library: Download tkotosz/fn-fdk-php library. Choose the download type require.
2. Extract the ZIP file and open the index.php.
3. Add this code to the index.php.
<?php
require_once('vendor/autoload.php');
/* Start to develop here. Best regards https://php-download.com/ */
$fdk->handle(function ($input, $context) use ($fdk) {
return $context->getHeaders(); // this will return all request headers as json
}, ['inputMode' => 'string']);