.NET - The top 5 decompilers

ILSpy

(free. open source)

Download from ilspy.net

dotpeek

(free, JetBrains)

Download from www.jetbrains.com/decompiler/download/

CodeReflect

(free, DevExtras)

Download from www.devextras.com/decompiler/

JustDecompile

(free, Telerik)

Download from www.telerik.com/products/decompiler.aspx

Reflector

($95/$195, Red Gate)

Download from www.red-gate.com/products/dotnet-development/reflector/

The source code for the test DLL used above:

  using System;
  
  namespace test1
  {
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("test1 console app");
            var p = new Program();
            p.Run();
        }
  
        void Run()
        {
            Console.WriteLine("hello");
        }
    }
  }