Smart Citizen offers an alternative to the centralised data production and management systems used by the large corporations that constitute the driving force behind the smart city concept. The project empowers ordinary citizens to gather information on their environment and make it available to the public. Started in 2012 in Fab Lab Barcelona at IAAC, we develop tools for citizen action in environmental monitoring and accompanying methodologies for community engagement and co-creation. We believe data is critical to inform political participation at all levels.