dotPeek is a free .NET decompiler and assembly browser. The main idea behind dotPeek is to make high-quality decompiling available to everyone in the .NET community, free of charge.
dotPeek decompiles any .NET assemblies and presents them as C# or IL code. Supported file types include:
Executable files (.exe)
Windows 8 metadata files (.winmd)
NuGet packages (.nupkg)
Microsoft Visual Studio Extensions packages (.vsix)
To assist you in working with compiled assemblies, dotPeek provides lots of features for:
dotPeek borrows most of its features from JetBrains ReSharper, a developer productivity tool for Microsoft Visual Studio.
Windows Explorer Integration
dotPeek allows opening assemblies right from the Windows Explorer by right-clicking on them and choosing Browse with JetBrains dotPeek. If you're deploying dotPeek using the installer, Windows Explorer integration is enabled automatically. However, if you're using the portable distribution, you need to tick the Integrate with Windows Explorer check box on the page of dotPeek options to enable Windows Explorer integration.