Sending data using POST to external url should be done by using drupal_http_request.
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$url = 'http://browse-tutorials.com/json';
'method' => 'POST',
'name' => 'POST data',
'description' => ' To external url in Drupal 7.',
)),
));
// Decode json data if requested data is json.
$result = drupal_json_decode($post_request->data));Programming Language: PHP