using System;

using System.IO;

using Newtonsoft.Json;

using System.Diagnostics;

​

public class Program

{

    public static void Main()

    {

        string original = 

        @"{

            ""id"" : 1,  

            ""name"" : ""foo"",

            ""child"" : { ""a"" : ""b"", ""c"" : ""d"" },

            ""array"" : [ { ""x"" : 1, ""y"" : 2 }, { ""x"" : 3, ""y"" : 4 } ]

        }";

        var sw = Stopwatch.StartNew();

        string minified = JsonHelper.Minify2(original);

        Console.WriteLine(minified);

        Console.WriteLine();        

        sw.Stop();

        Console.WriteLine("Minify2: {0}", sw.Elapsed);

        sw.Restart();

        minified = JsonHelper.Minify1(original);

        sw.Stop();

        Console.WriteLine(minified);

        Console.WriteLine();        

        Console.WriteLine("Minify1: {0}", sw.Elapsed);

        string beautified = JsonHelper.Beautify(minified);

        Console.WriteLine(beautified);

    }

}

​

public static class JsonHelper

{

    public static string Minify1(string json)

    {

        return ReformatJson(json, Formatting.None);

    }

    public static string Minify2(string json)

    {

        return Newtonsoft.Json.Linq.JObject.Parse(json).ToString(Formatting.None);

    }

    public static string Beautify(string json)

    {

        return ReformatJson(json, Formatting.Indented);

    }

    public static string ReformatJson(string json, Formatting formatting)

    {

        using (StringReader stringReader = new StringReader(json))

        using (StringWriter stringWriter = new StringWriter())

        {

            ReformatJson(stringReader, stringWriter, formatting);

            return stringWriter.ToString();

        }

    }

    public static void ReformatJson(TextReader textReader, TextWriter textWriter, Formatting formatting)

    {       

        using (JsonReader jsonReader = new JsonTextReader(textReader))

        using (JsonWriter jsonWriter = new JsonTextWriter(textWriter))

        {

            jsonWriter.Formatting = formatting;

            jsonWriter.WriteToken(jsonReader);

        }       

    }

}

​