"With a large part of the built environment privately owned in many European cities, citizen engagement is crucial for the success of sustainability initiatives in urban areas. The use of digital platforms and tools can support this process, given their potential to enable remote participation, reach a large number of citizens, and enhance governance transparency. However, many digital platforms for citizen engagement in sustainability action remain underutilised.

This study adopts a user-centric perspective to analyse the interface design of over ten digital platforms and identify design elements that hinder or foster engagement. Our analysis highlights four main interface issues: disconnection between scientific data and personal experience, complex navigation, information overload, and limited opportunities for action.

To overcome these limitations, we developed a set of design guidelines addressing four themes: Awareness and framing, Individual and collective action, Effective use of data, and Navigation and visuals. We implemented these guidelines in two prototypes, focusing on heat waves and biodiversity loss in urban areas. The prototypes were tested in workshop settings with positive feedback from participants, corroborating the importance of citizen-centric interface design in ensuring effective citizen engagement."