Abstract: A web application development environment and method employs an extensible user interface (XUI) Framework for creating GUI-managing components written in a declarative format for handling GUI components in a web application. The GUI-managing components are coordinated in a view presentation layer by a Controller in an Extended-Model-View-Controller (XMVC) pattern in conjunction with the business logic layer. The Controller is invoked by a user request for a web page and in turn invokes the GUI-managing components to parse information contained in a corresponding web application file for the requested web page in order to determine the templates and sub-templates to be invoked for handling the GUI components. Each template has a mode value which is set by mode information contained in the web application file for the requested web page. The XUI Framework has the ability to handle a rich set of GUI components without having to implement web applications development technologies.