Use C# HttpWebRequest to send json to web service
First of all you missed ScriptService attribute to add in webservice.
[ScriptService]
After then try following method to call webservice via JSON.
var webAddr = "http://Domain/VBRService.asmx/callJson"; var httpWebRequest = (HttpWebRequest)WebRequest.Create(webAddr); httpWebRequest.ContentType = "application/json; charset=utf-8"; httpWebRequest.Method = "POST"; using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream())) { string json = "{\"x\":\"true\"}"; streamWriter.Write(json); streamWriter.Flush(); } var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse(); using (var streamReader = new StreamReader(httpResponse.GetResponseStream())) { var result = streamReader.ReadToEnd(); return result; }