Castle is an open source project for .NET that aspires to simplify the development of enterprise and web applications. Offering a set of tools (working together or independently) and integration with others open source projects, Castle helps you get more done with less code and in less time.

The Castle MicroKernel is an inversion of control container that was designed towards extensibility. It combines facilities to grow orthogonally. These facilities work side-by-side, without interfering or depending on each other, to allow you to easily extend the container functionality by plugging in new concerns and semantics. You can use it as an embeddable container on tools that support extensions or plugin support, such as tools which exposes configurable pipelines or compilers. The container is set up and configured through code, and can be extended to work with a configuration system that your project supports. Castle Windsor aggregates the MicroKernel and exposes a powerful configuration support. It is suitable for common enterprise application needs. It is able to register facilities and components based on the configuration and adds support for interceptors.

EPiAbstractions provides facades for many of the classes in EPiServers products which enable its users to decouple their code from the concrete implementations and thereby gaining the ability to unit test code that otherwise would depend on the concrete implementations.

NHibernate is a mature, open source object-relational mapper for the .NET framework. It's actively developed , fully featured and used in thousands of successful projects.

Page Type Builder allows developers to define EPiServer page types in code which eliminates the need to synchronize page types between different servers. As page types are declared in code it also enables inheritance between page types and strongly typed property access.