Abstract <p>Building decarbonization through energy renovation is a key challenge across the European Union, particularly in social housing sectors marked by high vulnerability. To support this goal, this study introduces a GIS-based open-access web tool for evaluating the energy performance and social vulnerability of the existing residential stock at the urban scale. The tool integrates data from public and open-source databases into a georeferenced environment, enabling systematic characterization of geometric, constructional, energy and social parameters at the urban-level, and supporting bottom-up and top-down approaches. This allows for performance evaluations, simulation model construction and the identification of high-priority buildings through energy and socioeconomic vulnerability indicators. Results from the city of Seville, used as a case study involving 2,888 dwellings) reveal that over 90% of buildings present severe winter energy vulnerability, while summer vulnerability is generally low. Socioeconomic analysis shows that more than a third of buildings house users living in severe poverty conditions. The combined vulnerability index highlights specific neighbourhoods, such as Polígono Sur, with particularly acute vulnerability levels. The tool’s scalability was demonstrated by extending it to 41 municipalities in southern Spain. This study concludes that this approach enables detailed diagnosis of structural and energy-related inequalities, integrating and analysing existing open data to perform thorough building performance assessment at urban level, and offers a rapid and reliable method for acquiring key building data and ensuring long-term adaptability through continuous updates.</p>