RestSharp

 public async Task CreateUserAsync(InputUser user)
 {
     var request = new RestRequest("/api/v1/users", Method.Post);
     request.AddHeader("content-type", "application/json");
     request.AddHeader("authorization", "Bearer " + GetAuthToken());
     request.AddParameter("application/json", JsonConvert.SerializeObject(user), ParameterType.RequestBody);

     var response = await RestClient.ExecutePostAsync(request);

     if (response.StatusCode != HttpStatusCode.Created)
         throw new HttpRequestException("status: " + response.StatusCode + " - " + response.Content,
             response.ErrorException);
   
 }