<?php
//API Url
$url = 'http://example.com/api/JSON/create';
//Initiate cURL.
$ch = curl_init($url);
//The JSON data.
$jsonData = array(
'username' => 'MyUsername',
'password' => 'MyPassword'
);
//Encode the array into JSON.
$jsonDataEncoded = json_encode($jsonData);
//Tell cURL that we want to send a POST request.
curl_setopt($ch, CURLOPT_POST, 1);
//Attach our encoded JSON string to the POST fields.
curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonDataEncoded);
//Set the content type to application/json
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
//Execute the request
$result = curl_exec($ch);
http://thisinterestsme.com/sending-json-via-post-php/