C#/ASP.Net Sample Code

        
            using System;

            using System.Net;
            using System.IO;

            namespace Rextester
            {
              public class Program
                {
                  public static void Main(string[] args)
                    {
                      var httpWebRequest = (HttpWebRequest)WebRequest.Create("https://app.multitexter.com/v2/app/sms");
                      httpWebRequest.ContentType = "application/json";
                      httpWebRequest.Method = "POST";
                      ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;

                      using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
                      {
                        string email = "your multitexter registered email ";
                        string password = "Your password";
                        string message = "message content";
                        string sender_name = "Your sender name ";
                        string recipients = "mobile numbers seperated by comma e.9 2348028828288,234900002000,234808887800";
                        string forcednd = "set to 1 if you want DND numbers to receive message otherwise set to zero";
                        string json = "{\"email\":\""+email+"\",\"password\":\""+password+"\",\"message\":\""+message+"\",\"sender_name\":\""+sender_name+"\",\"recipients\":\""+recipients+"\",\"forcednd\":\""+forcednd+"\"}";
                        streamWriter.Write(json);
                        streamWriter.Flush();
                        streamWriter.Close();
                      }

                        var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                        using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
                      {
                        var result = streamReader.ReadToEnd();
                        Console.WriteLine(result);
                      }
                    }
                }
            }