Simple api to capture and test API callbacks

api.php

<?php

$log = __DIR__ . '/api.log';
if ('POST' == $_SERVER['REQUEST_METHOD']) {
  $payload = json_decode(file_get_contents('php://input'), true) ?: $_POST;
  file_put_contents(
    $log,
    sprintf(
      "[%s] (%s - %s) %s\n",
      (new \DateTime())->format('Y-m-d H:i:s'),
      $_SERVER['REMOTE_ADDR'],
      gethostbyaddr($_SERVER['REMOTE_ADDR']),
      var_export($payload, 1)
    ),  
    FILE_APPEND
  );  

  exit('OK' . PHP_EOL);
} else {
  if (file_exists($log)) {
    echo '<pre>' . file_get_contents($log);
  } else {
    echo 'No log file under ' . $log;
  }
}