Advancing circularity in metropolitan areas involves planning, co-designing and implementing spatially explicit interventions with a multitude of stakeholders who are required to work with waste and resource management information. For the stakeholders, understanding information on these flows of resources and materials, and the spatial implications of these flows across the territory, is crucial when proposing new interventions and assessing the effects of these interventions. Spatial decision support systems constitute potential tools for supporting groups of stakeholders involved in the collaborative process of shaping the future of urban areas while achieving sustainability and increased circularity. This chapter focuses on the digital representation and portrayal, and the use of different types of information in a digital spatial decision support tool aimed at helping decision-makers through stages of the collaborative process that starts at problem identification and status quo understanding, and finishes at the proposed circular economy strategies for a metropolitan area. The way in which information is modeled and presented in the tool is largely based on the geodesign methodology, and is specific to individual stages of the planning process. The tool presents information relevant to a peri-urban area through different mediums: web maps and charts to describe the study area, Sankey diagrams linked with dynamic flow maps to portray its resource flow streams, and the integration of the above to portray and assess the scenarios developed jointly by the stakeholders. The tool was implemented in an interactive web application and applied to the collaborative process of developing spatial strategies for advancing circularity in the Amsterdam Metropolitan Area. A series of interconnected workshops were held with stakeholders, who used the tool to guide them through the stages of the co-development of the strategies. Stakeholders were presented with spatial information about the study area’s current resource and waste management situation in the form of web maps and the spatial distribution and dynamics of resource flows. This chapter describes how all this information was portrayed, presented, and used within the interactive web application at the collaborative workshops.@en