Source –> https://gist.github.com/chkn/4748252

using System;
using System.Linq;

public static class JSON 
{
    public static string Stringify (object obj)
    {
        string str;
        if (obj == null) return "null";
        if (obj is ValueType) return obj.ToString ().ToLowerInvariant ();
        if ((str = obj as string) != null) return System.Text.RegularExpressions.Regex.Escape (str);

        // assume it's a POCO
        return "{" + string.Join (",",
            from p in obj.GetType ().GetProperties ()
            let json = (JSONAttribute) p.GetCustomAttributes (typeof (JSONAttribute), true).FirstOrDefault ()
            where json != null
            select "\"" + (json.Key ?? p.Name) + "\":" + Stringify (p.GetValue (obj, null))
        ) + "}";
    }
}

public class JSONAttribute : Attribute
{
    public string Key { get; set; }
    public JSONAttribute () {}    
    public JSONAttribute (string key) { Key = key; }
}