The smart city has been both celebrated for opening up decision-making processes through responsive digital infrastructures, and criticised for turning citizens into mere nodes of socio-technical networks under corporate or government control. In line with these depictions, smart city politics is often analysed as a struggle between aspirations for bottom-up participatory democracy and authoritarian control. Drawing on ethnographic research on an Amsterdam project which encourages citizens to collect and share air quality data, we problematise this vertical reading of smart city politics. The project mobilises both republican citizenship and cybernetic citizenship, each assuming different logics regarding the ways in which citizens negotiate urban life by means of data and sensing technologies. While republican citizenship emphasises citizens’ sovereignty, cybernetic citizenship emphasises their immersion into informational environments. We demonstrate how, depending on specific situated interests and forms of engagement, both kinds of citizenship feed into appealing visions of urban life for different actors.