We can do a raw POST with cURL library, which can send text data to server, such as json, xml, html and so on. Just convert data to string, and put in curl_setopt($curl, CURLOPT_POSTFIELDS, $data) 。

Example

function post($url, $data, $headers)
{
    $curl = curl_init();
    curl_setopt_array($curl, array(
        CURLOPT_URL => $url,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT => 0,
        CURLOPT_CUSTOMREQUEST => "POST",
        CURLOPT_POSTFIELDS => $data,
    ));
    if (!empty($headers)) {
        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
    }
    $response = curl_exec($curl);
    $errno = curl_errno($curl);
    if ($errno) {
        return false;
    }
    curl_close($curl);
    return $response;
}

Submit JSON data

Use it.

$arr = [
    "name" => "test",
    "password" => "123456",
];
$data = json_encode($arr, JSON_UNESCAPED_SLASHES);
$headers = ["Content-Type: application/json"];
echo post("http://localhost/response.php", $data, $headers);

reponse.php

$raw = isset($GLOBALS["HTTP_RAW_POST_DATA"]) ? $GLOBALS["HTTP_RAW_POST_DATA"] : null;
$data = json_decode($raw, JSON_OBJECT_AS_ARRAY);
print_r($data);

Output

Array
(
    [name] => test
    [password] => 123456
)

Submit XML data