using System;

using System.IO;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""Employees"": [

                {

                  ""FIrstName"": ""John"",

                  ""LASTname"": ""Doe""

                },

                {

                  ""FIRSTNAME"": ""Anna"",

                  ""LaSTNaME"": ""Smith""

                },

                {

                  ""firstName"": ""Peter"",

                  ""lastName"": ""Jones""

                }

              ]

            }";

​

        JToken token = JsonHelper.DeserializeWithLowerCasePropertyNames(json);

        Console.WriteLine(token.ToString());

    }

}

​

public static class JsonHelper

{

    public static JToken DeserializeWithLowerCasePropertyNames(string json)

    {

        using (TextReader textReader = new StringReader(json))

        using (JsonReader jsonReader = new LowerCasePropertyNameJsonReader(textReader))

        {

            JsonSerializer ser = new JsonSerializer();

            return ser.Deserialize<JToken>(jsonReader);

        }

    }

}

​

public class LowerCasePropertyNameJsonReader : JsonTextReader

{

    public LowerCasePropertyNameJsonReader(TextReader textReader)

        : base(textReader)

    {

    }

    public override object Value

    {

        get

        {

            if (TokenType == JsonToken.PropertyName)

                return ((string)base.Value).ToLower();

            return base.Value;

        }

    }

}

​