using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""Success"": true,

              ""Records"": [

                {

                  ""f_EMail"": ""test@me.com"",

                  ""f_FirstName"": ""firstname"",

                  ""f_LastName"": ""lastname"",

                  ""f_Country"": ""Luxembourg""

                },

                {

                  ""f_EMail"": ""test2@me.com"",

                  ""f_FirstName"": ""firstname2"",

                  ""f_LastName"": ""lastname2"",

                  ""f_Country"": null

                }

              ]

            }";

        Result result = JsonConvert.DeserializeObject<Result>(json);

        foreach (Record rec in result.Records)

        {

            Console.WriteLine("Email: " + rec.Email);

            Console.WriteLine("FirstName: " + rec.FirstName);

            Console.WriteLine("Additional properties:");

            foreach (var kvp in rec.Data)

            {

                Console.WriteLine("  " + kvp.Key + ": " + kvp.Value);

            }

            Console.WriteLine();

        }

    }

}

​

public class Result

{

    public bool Success { get; set; }

    public IEnumerable<Record> Records { get; set; }

}

​

public class Record

{

    [JsonExtensionData]

    public Dictionary<string, object> Data { get; set; }

    [JsonProperty("f_EMail")]

    public string Email { get; set; }

    [JsonProperty("f_FirstName")]

    public string FirstName { get; set; }

}

​