As you probably know, ASP.NET MVC, Web API, and Web Pages are available as open source on aspnetwebstack.codeplex.com. If you want to go beyond using the official RTM versions and either use the latest nightly drops, compile it yourself, or create pull requests then here’s a decoder ring for how to get started:
For when you want to try out the latest nightly NuGet packages from our preview feed without having to compile the source.
For when you run into trouble using the nightly NuGet packages or want to see what is going on. Makes full source and symbols available directly in the Visual Studio Debugger.
For when you want to compile the source and run unit tests yourself.
For when you want to make source contributions back to the project. It explains how to create a fork and make a pull request with your proposed changes.