During the past decade we have been witnesses of the rise of the Web Application with a browser based client. This brought us ubiquitous access and centralized administration and deployment, but the inherent limitations of the approach however, and the availability of new technologies like XML and Web Services has made people start building rich clients as business applications front ends. But very often these applications are tied to the development tools and very hard to extend. We propose a clean and elegant architecture which considers a plugin based approach as a general solution to the extensibility problem. The approach is demonstrated by refactoring a simple application taken from a public forum into the proposed architecture including two new extensions that are implemented as plugins.