using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

public class Program

{

    public static void Main()

    {

        string json = 

@"{

  ""FirstObject"": {

    ""NestedObject"": {

      ""AttributeString"": ""ok"",

      ""AttributeNumeric"": 123.45

    },

    ""OtherObject"": [

      {

        ""ArrayVal"": 100

      },

      {

        ""ArrayVal"": 200

      }

    ]

  }

}";

        Console.WriteLine("----- Original JSON ---");

        Console.WriteLine(json);

​

        var obj = JsonConvert.DeserializeObject<RootObject>(json);

        var settings = new JsonSerializerSettings

        {

            ContractResolver = new DefaultContractResolver

            {

                NamingStrategy = new SnakeCaseNamingStrategy

                {

                    ProcessDictionaryKeys = true

                }

            },

            Formatting = Formatting.Indented

        };

        json = JsonConvert.SerializeObject(obj, settings);

        Console.WriteLine("----- Converted to snake_case ---");

        Console.WriteLine(json);

​

        obj = JsonConvert.DeserializeObject<RootObject>(json, settings);

        json = JsonConvert.SerializeObject(obj, Formatting.Indented);

        Console.WriteLine("----- Converted back to UpperCamelCase ---");

        Console.WriteLine(json);

​

    }

}

​

public class RootObject

{

    public FirstObject FirstObject { get; set; }

}

​

public class FirstObject

{

    public NestedObject NestedObject { get; set; }

    public OtherObject[] OtherObject { get; set; }

}

​

public class NestedObject

{

    public string AttributeString { get; set; }

    public string AttributeNumeric { get; set; }

}

​

public class OtherObject

{

    public string ArrayVal { get; set; }

}

​