Mailchimp API v3: Save member to a specific list in PHP

php_mailchimp.php

<?php
    /* RESOURCES
    * API Overview: http://kb.mailchimp.com/api/article/api-3-overview
    * Endpoint doc: http://kb.mailchimp.com/api/resources/lists/members/lists-members-collection
    * I highly recommend to check out the API Playground and check the available params and how to create the call depending on you need: 
    * http://kb.mailchimp.com/api/article/about-the-playground
    */
    $mc_api_key = MAILCHIMP_API_KEY;
    $mailchimp_url_endpoint = 'https://us3.api.mailchimp.com/3.0/lists/547a212260/members'; 
    $current_date_time = new DateTime("now", new DateTimeZone('America/Mexico_City'));

    $data = array(
      'email_address' 		=> $email,
      'status' 		        => 'subscribed',
      'ip_opt' 			=> $_SERVER['REMOTE_ADDR'],
      'timestamp_opt'	    	=> $current_date_time->format(DateTime::ISO8601),
      'merge_fields' 	    	=> array('FNAME' => $firstName, 'LNAME' => $lastName),
      'language'	        => 'es'
    );
    
    $data_as_json = json_encode($data);
    
    $ch = curl_init($mailchimp_url_endpoint);

    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json', 'Authorization: api-key ' . $mc_api_key));
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_TIMEOUT, 5);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt( $ch, CURLOPT_POSTFIELDS, $data_as_json);

     $response = curl_exec($ch);
     $call_info = curl_getinfo($ch);
     curl_close($ch);
?>