When talking about the foundation necessary to build smarter, digital cities, the focus is often on ubiquitous broadband, wireless access or sensors – in other words hardware. However, another important ingredient is data, ideally of the open flavour. In other words, open data is one of the key enablers for better services, improved opportunities for citizen participation and new business models (have a look at lokaler for a startup making use of open data). In this discussion, open data is often named synonymously with open government data, i.e., public sector data from local, national or even international government bodies. However, public sector data is not all there is – open data can also include data from businesses (opening hours, details of product and service offers, locations, etc.), from non-governmental organisations, or even from individual citizens.