The increasing growth in size and complexity of portals calls for a systematic way to web-application development that is able to face the stringent demands imposed on both the development and maintenance of these systems Model-based approaches have been proposed to mitigate this situation. These approaches aim to find models, preferably orthogonal, that allow designers to declaratively specify a distinct concern of the application without being immediately immersed in details of implementations. This paper presents AtariX, a model-based tool that renders HTML pages from the declarative schemata specified by the designer. Each concern is described by a separate XML document: how data is integrated and structured (the content document), the topology of links (the navigation document) and the layout of each element (the presentation document). An application is then conformed by a set of schemata (i.e. model instances), for each of the distinct models. Separation of concerns and declarativeness enhance the application maintenability, as well as promoting concurrent development as each model can be assigned to a different team. AtariX has been fully implemented and its use is illustrated by designing and delivering a website for a scientific conference.