QGIS Web Client (QWC) is a Web-GIS client based on OpenLayers 2 and ExtJS and tailored to use special extensions of QGIS Server, such as extracting information from QGIS Project settings, extended GetFeatureInfo Requests, GetPrint and DXF export. It uses standard WMS/WFS commands, but extends them where needed. QWC is used by several cities and provinces in Europe. There are four main reasons why QWC needs to be overhauled: The code structure is not very modular and should be better structured. QWC only works well on Desktops. Despite a separate mobile web client based on OpenLayers 3 and jQuery Mobile, for maintenance reasons it would be much better to have a single web client that uses responsive design and works for all devices from a single viewer. The base libraries ExtJS 3.4 and Openlayers 2 have been phased out and there are newer versions available. However, the upgrade to the newer versions is not trivial. Having a more modern foundation based on newer web technologies This presentation discusses the requirements, the progress of this project, technical decisions taken and challenges solved during the project. While the first goal of the project is to establish a modern foundation for the coming years and reach feature parity with the old QWC project, it is already planned to implement a QWCII python plugin that offers a GUI and assists with the global configuration of the client. This tool should also facilitate the management of topics and projects.