using System;

using Newtonsoft.Json;

using System.Net;

using System.Text;

using System.IO;

public class Program

{

    public static void Main()

    {

        WebRequest tRequest = WebRequest.Create("https://fcm.googleapis.com/fcm/send");

        tRequest.Method = "post";

        //serverKey - Key from Firebase cloud messaging server  

        tRequest.Headers.Add(string.Format("Authorization: key={0}", "AAAAu352u-k:APA91bFuVZF6VFQcCjOHJpwwnroOHX3QpAJp4wibptv6M0PZFEUmmuBqhTLdEY8TvsAIV_VBMNaVtHgpF1R5WMV4C8DqMLlS8A7Nz1OYJ4vWSiFbL3h7RjHJnX3b8s4qGaxJ1XkVqnRJ"));

        //Sender Id - From firebase project setting  

        tRequest.Headers.Add(string.Format("Sender: id={0}", "805280594921"));

        tRequest.ContentType = "application/json";

        var payload = new

        {

            to = "this is message",

            priority = "high",

            content_available = true,

            notification = new

            {

                body = "Test",

                title = "Test",

                badge = 1

            },

        };

​

        string postbody = JsonConvert.SerializeObject(payload).ToString();

        Byte[] byteArray = Encoding.UTF8.GetBytes(postbody);

        tRequest.ContentLength = byteArray.Length;

        using (Stream dataStream = tRequest.GetRequestStream())

        {

            dataStream.Write(byteArray, 0, byteArray.Length);

            using (WebResponse tResponse = tRequest.GetResponse())

            {

                using (Stream dataStreamResponse = tResponse.GetResponseStream())

                {

                    if (dataStreamResponse != null) using (StreamReader tReader = new StreamReader(dataStreamResponse))

                        {

                            String sResponseFromServer = tReader.ReadToEnd();

                            //result.Response = sResponseFromServer;

                            Console.WriteLine("Success");

                        }

                }

            }

        }

    }

}