c#

        string URLAuth = "https://khalti.com/api/v2/payment/verify/";
        string postString = "{\"token\" : \"" + token + "\", \"amount\" : " + amt + " }";

        const string authorization_key = "Key test_secret_key_26c3759a78884aecb70f7662e2ab3809";

        var request = (HttpWebRequest) WebRequest.Create(URLAuth);

        var postData = "{\"token\" : \"" + token + "\", \"amount\" : " + amt + " }";

        //var data = Encoding.UTF8.GetBytes(postData);
        var data = Encoding.ASCII.GetBytes(postData);

        request.Method = "POST";
        request.ContentType = "application/json";
        request.Headers.Add("Authorization", authorization_key);
        request.ContentLength = data.Length;
        var stream = request.GetRequestStream();

        using (stream)
        {
            stream.Write(data, 0, data.Length);
        }
    
        Console.WriteLine("Request " + request.ContentLength.ToString());
        //Console.ReadLine();
        
        try{
            var response = (HttpWebResponse)request.GetResponse();
            var responseData = new StreamReader(response.GetResponseStream()).ReadToEnd();  
			//lblKhaltiResponse.Text = responseData;
        } catch (WebException e){
             using (WebResponse response = e.Response)
            {
                HttpWebResponse httpResponse = (HttpWebResponse) response;
                Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
                using (Stream data1 = response.GetResponseStream())
                using (var reader = new StreamReader(data1))
                {
                    string text = reader.ReadToEnd();
                    Console.WriteLine(text);
                }
            }
        }