<?php
// set post fields
$post = [
'username' => 'email',
'password' => 'pass',
];
$ch = curl_init('https://web.ewa.ua/ewa/api/v12/user/login');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
// execute!
$response = curl_exec($ch);
// close the connection, release resources used
curl_close($ch);
// do anything you want with your response
var_dump($response);
echo $response;