you can sent json through Http post in cakephp
    <?php
 $data = array('Users'=>array('id'=>'1','username'=>'xyz','password'=>'pass','email'=>'[email protected]','age'=>'28','gender'=>'male')); 
$url = "http://localhost/appname/Controllername/functionname";
    $content = json_encode($data);
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_POSTFIELDS, 'data=".$content);
    $json_response = curl_exec($curl);
    echo $json_response;?>
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solved How to write REST web service in cakephp using Post ..? [closed]