Open data portals have been a primary source for publishing datasets from various sectors of administration, all over the world. However, making open data available does not necessarily lead to better utilisation from citizens and businesses. Our paper presents a new framework and a prototype system for supporting open application development by citizen communities, through gathering and making available open data and open web services sources from governmental actors, combined with an application development environment, training material and application examples. This is a presentation of Gov4All platform, a web site for managing citizen-driven development in Greece.