I am currently using PHP CURL but somehow it is not working for basicAUTH in my case. I want to use guzzel HTTP client in simple PHP project (not a Laravel project). Every solution on the internet I found is setting up in laravel and installing it via composer. 
$client = new \GuzzleHttp\Client();
$response = $client->post($service_url, [
    'auth' => [
        $username, 
        $admin_password
    ]
]);
or if guzzel do not works with simple PHP, Suggest other client which can work with simple PHP for basic Auth. Thanks