This paper discusses the design of “I finded,” a mobile app aimed at mapping and promoting second-hand clothing stores within Porto’s historic centre. Developed as part of a master’s thesis at the University of Porto in 2023, the app addresses the rising interest in second-hand clothing and the limited awareness of such shops in Porto. Given the fashion industry’s significant environmental impact, the project encourages sustainable shopping choices to o support eco-conscious consumer behavior and environmental sustainability. The app’s main goal is to make second-hand stores more accessible, featuring a consistent store page format with a summary, image carousel, style description, target demographics, customer reviews, location with map, and contact details. Research methods included questionnaires, interviews, visual analysis, and observation, with a focus on inclusivity, diversity, and usability in design. Two shops, “Kilo” and “Com Sotaque,” served as test cases, each offering unique aesthetics within the second-hand market. By integrating sustainability into design, this project aims to promote environmental conservation and encourage a sustainable future. The app represents a concrete outcome, with the next step being potential collaborations with local institutions to bring it to life.