The Windows Communication Foundation (or WCF), previously known as "Indigo", is a runtime and a set of APIs in the .NET Framework for building connected, service-oriented applications.

Windows Communication Foundation (WCF) is a framework for building service-oriented applications. Using WCF, you can send data as asynchronous messages from one service endpoint to another. A service endpoint can be part of a continuously available service hosted by IIS, or it can be a service hosted in an application.