using System;

using System.Text;

using Newtonsoft.Json;

​

public static class ByteExtensions

{

    public static string Base64Decode(this byte[] input)

    {

        return Encoding.UTF8.GetString(input);

    }

}

​

public class Program

{

    public static void Main()

    {

        var payload = "eyJidWlsZFV1aWQiOiIyODk5OWMzZC1lZGUzLTRmMDktYTIyZi0zNTMyZDA3ZDkxZDEiLCJwcm9qZWN0VXVpZCI6ImNkZWZiMmJjLTJlMzAtNDExZS1iOThhLWVlNGVkYmVjYTE4YiIsImlhdCI6MTY0NDUzMTU2NiwiZXhwIjoxNjUyMzA3NTY2fQ";

        var obj = Newtonsoft.Json.JsonConvert.DeserializeObject(Convert.FromBase64String(payload).Base64Decode()); 

        Console.WriteLine(JsonConvert.SerializeObject(obj, Formatting.Indented));   

    }

}