Within IRIS project, the application USERfit Tool was developed in order to facilitate the use of the USERfit design environment. USERfit methodology was developed within the USER (TIDE-1062) European project [Poulson D., Ashby M., Richardson S. (1996). USERfit: A practical handbook on user centred design for assistive technology. ECSC-EC-EAEC, Brussels-Luxembourg]. USERfit is a well-established methodology focused on the generation of usability specifications. It was specifically created for the Assistive Technology field, and proved to be very suitable for the Design for All paradigm. The main purpose of USERfit is the capture, and specification, of user requirements. This methodology uses paper-based forms to store and propagate the design related information. For this reason, some issues, such us the inclusion and elimination of new users or contexts of use or the need to propagate the results between forms, could make the specification process tedious. USERfit Tool was created in order to take advantage of USERfit methodology avoiding the need to handle large numbers of paper forms and automating the most tedious parts of its use. Its structure accurately reproduces the protocols defined by USERfit, enables the reuse of previous specifications and allows the design to be shared among remote groups with homogeneous results. Usability analysis has been carried out in order to confirm that this tool fits the needs and working styles of its users: the designers.