Problems such as traffic congestion, safety and pollution are difficult to tackle as the mitigation involves multiple urban stakeholders. The aim of LOOPER is to build a participatory co-creation methodology and platform to demonstrate ‘learning loops’ i.e. new ways of decision-making that bring together citizens, stakeholders and policy-makers to iteratively learn how to address such urban challenges. The methodology addresses the whole co-creation process. Citizens and stakeholders debate on topical issues, then frame the problem and collect data. The Looper platform visualizes the data, and enables the co-design of solutions which are evaluated and the best are put into practice and monitored.