The Swiss Federal Office of Topography (swisstopo) is the national centre of competence with regard to geographically referenced data. It provides, for example, national maps, elevation and landscape models, satellite images and orthophotos. The geodata portal of the Swiss Confederation is operated by the Federal Office of Topography, swisstopo on behalf of the coordinating agency for federal geographical information. All federal data is accessible via the internet at http://www.geo.admin.ch/ and the maps specifically via http://map.geo.admin.ch. Nowadays the internet isn’t accessed solely by desktop computers with big-screens and precise user-input devices like the mouse but also with a myriad of other devices including smartphones. This usage pattern is increasing steadily. Many data-content providers in the WWW take this into account when they provide specialized versions of their websites for users with such devices. While geo.admin.ch provides a great API for their data access and an easy interface for building web GIS applications, mobile users weren’t receiving special attention until now. terrestris received a contract to remedy this problem specifically for the mapviewer. Using OpenLayers and Sencha Touch an open source mobile web mapping client more or less comparable to GeoExt is being developed by terrestris. Our partner OpenGeo is helping in developing a sustainable solution by providing us with expert reviews from their team of specialists. This client will enable the user to browse the geodata offered by the Swiss Confederation using the touch-screen functionality of mobile devices. For a first impression you can use a mobile device and check out the following examples: http://dev.geoext.org/sandbox/gxm/geoext/gxm/examples/mappanel.html http://dev.geoext.org/sandbox/gxm/geoext/gxm/examples/layerlist.html http://dev.geoext.org/sandbox/gxm/geoext/gxm/examples/buttons.html