public HttpResponseMessage GetPinWithUserIDs(dynamic req) { double since = req.since; int takeCnt = req.takeCnt; List<string> users = req.users.ToObject<List<string>>(); PinsService pinService = new PinsService(); string yourJson = JsonConvert.SerializeObject(pinService.GetPinWithUserIDs(users, since, takeCnt)); var response = this.Request.CreateResponse(HttpStatusCode.OK); response.Content = new StringContent(yourJson, Encoding.UTF8, "application/json"); return response; }