C#

string credentialsJson = @"{""username"":""test"",
                                          ""password"":""test"" 
                                       }";

            int tmp = ServicePointManager.DefaultConnectionLimit;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(@"https://qrua.com/qr/service" + @"/auth/login");
            request.Method = "POST";
            request.KeepAlive = true;
            request.Timeout = 50000 ;
            request.CookieContainer = new CookieContainer();
            request.ContentType = "application/json";
            try
            {
                StreamWriter writer = new StreamWriter(request.GetRequestStream());
                writer.Write(credentialsJson);
                writer.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine("EXCEPTION:" + e.Message);
            }

            //WebResponse response = request.GetResponse();
            try
            {
                using (WebResponse response = (HttpWebResponse)request.GetResponse())
                {
                    Console.WriteLine("request:\n" + request.ToString() + "\nresponse:\n" + response.ContentLength);
                    response.Close();
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("EXCEPTION: in sending http request:" + " \nError message:" + e.Message);
            }

ArrayList sd = new ArrayList(); // PDF streams array
sd.Add(new ArrayList());          // array for the stream_beginning offset (long)
sd.Add(new ArrayList());          // array for the stream_end offset (long)
sd.Add(new ArrayList());          // array for the stream_content utf8.toString(s,2)