This paper presents a framework dedicated to the design of geographic web applications. This framework includes three generic design models that allow designers to build a geographic application according to three dimensions: geographic content, content rendering and display, and interactive behaviour. The three design models allow designers to develop applications for elementary tasks to achieve a specific goal. They are expressive enough to describe a wide variety of geographic applications. They are operational as they are translated into executable code. This executability supports an agile design process based on short cycles where designers can refine their needs as many times as necessary by specifying, executing and evaluating their application. Modeling is performed using visual languages. In particular, the interactive behaviour is specified with a language inspired from the UML sequence diagram. We have demonstrated that this language is sufficiently simple to be understood by domain experts (e.g., education, tourism, culture) with no computer science background. We have developed WINDMash, an authoring environment, to assess our approach, as well as the models and the design languages with a diversity of geographic Web applications.