Web application designers should be able to integrate different methods and techniques in order to correctly organize the overall design-implementation-test process. The conceptual model plays an important part in the development process [1].

Considering that no model can be exploited to its maximum potential unless it is supported by a proper set of development tools, in this paper we present MODE, a tool for conceptual modeling of web applications based on UWA methodology and on the related HDM2000 model.

In MODE the designer can work simultaneously at different levels and on different parts of the design in accordance with UWA methodology.

After a first off-line version of MODE based on Microsoft Visio a second it is available a new on-line editor based on Microsoft .Net framework. Both these versions allow the production of well-organized design documents using the Microsoft office automation features. In particular the on-line version, introduced in this paper, open new ways to the cooperative design.

According to Rational Rose that has demonstrated the benefits derived from the adoption of a design tools with prototyping features, MODE can be used in conjunction with WARP, a fast prototyping system for Web applications. A real life experience of the use of the methodology and of the MODE are reported.