BoltOn is an open source application framework to help develop simple/modular/extensible/unit-testable .NET applications (Console, MVC, WebAPI, Windows Service etc.,) with reduced boilerplate code. The components are written in such a way that they're modular, thus they can be added on with other components and interchanged easily, and hence the name Bolt-On.
Please go over the Documentation to know more about the framework.