FloodCitiSense aims at developing an urban pluvial flood early warning service for, but also by citizens and city authorities. This service will reduce the vulnerability of urban areas and citizens to pluvial floods, which cause serious damage to the urban environment. Citizens will be actively involved in the monitoring of rainfall and flooding, making use of low-cost sensors and web-based technologies. The early warning service will enable ‘citizens and cities’ to be better prepared and to better respond to urban pluvial floods. FloodCitiSense targets a co-creation of this innovative public service in an urban living lab context with all actors.