Urban and territorial planning processes are characterized by a high level of complexity that makes tools management dif?cult. This research presents a Web-GIS prototype for supporting urban planning and management decision-making processes towards social, economic and environmental sustainability. It is designed according to open-source technology and aims to de?ne new planning top-down and bottom-up approaches. The design criteria of this innovative platform respond to the essential principles of transferability, modularity, scalability, and data interoperability. This new tool is applied to a case study to demonstrate how it can support planners and local authorities in urban planning and management processes.