The EFx Factory (EFx Architectural-Guidance Software Factory) is a pioneering Architectural Guidance Software Factory from Microsoft, and one of the first implementations of a software factory to be built.

The ‘EFx Factory’ implements the .NET Distributed Architecture for Service-Oriented applications and services.

The factory is based upon an Architectural Application Framework called Enterprise Framework that describes a physical Microsoft .NET architecture leveraging Microsoft Enterprise Library and other service-oriented patterns from Microsoft patterns & practices. The EFX Factory was designed and built by development consultants within Microsoft Consulting Services in response to customer demand for an implementation of the .NET Architecture, best practices for .NET development, and guidance on best use of Enterprise Library and a number of other application blocks freely available from Microsoft.

Initially, (circa 2003, .NET Framework 1.0-1.1, Visual Studio 2002–2003) ‘Enterprise Framework’ (EFx) was built to meet growing customer demand for an implementation of the .NET architecture. The framework was based upon implementation patterns harvested from several enterprise solution implementations, for various customers. This framework implemented the layered .NET architecture and leveraged, and extended Enterprise Library to provide a complete framework for authoring applications and services on the .NET platform.