Open City Portal is an open-source platform developed by a network of several development institutions and universities to help even small cities in developing countries to be able to install their own customised citizen-centric city portals, through which the cities can achieve most of the e-Government goals: two-way communication with citizens and creating a single window for every city service categories. Using its knowledge sharing function, the Open City Portal supports various participatory urban and regional initiatives, such as sustainable cities, and Digital Local Agenda.