mailchimp_api_curl.php

$merge_vars=array(
    'FNAME'=>'Aabir',
    );
$email = '[email protected]';
$send_data=array(
    'email'=>array('email'=>$email),
    'apikey'=>"", //API KEY 
    'id'=>"", //List ID
    'merge_vars'=>$merge_vars,
    'double_optin'=>false,
    'update_existing'=>true,
    'replace_interests'=>false,
    'send_welcome'=>false,
    'email_type'=>"html",
);

$payload=json_encode($send_data);
$submit_url="https://us12.api.mailchimp.com/2.0/lists/subscribe.json";
$ch=curl_init();
curl_setopt($ch,CURLOPT_URL,$submit_url);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
curl_setopt($ch,CURLOPT_POST,true);
curl_setopt($ch,CURLOPT_POSTFIELDS,$payload);
$result=curl_exec($ch);
curl_close($ch);
$mcdata=json_decode($result);

var_dump($mcdata);