It is easier than ever to collect data about all kinds of aspects of daily life. This data can have significant value for the people who produce it, but also for corporations and governments. This chapter investigates how this process of ‘datafication’ operates in the space of the city, where globalization and other political-economic pressures have shifted the notion and practice of citizenship. Through an investigation of the concepts of ‘openness’ and ‘transparency’ the chapter highlights some significant shifts in the power relations related to data collection and use, and identifies directions for future research and policy making in this area.