Selecting the right tree species is a crucial step in designing sustainable and effective agroforestry systems. To support this process, several decision support systems (DSS) have been developed in various countries to help farmers and advisors choose appropriate species. However, these tools are often limited in reach—typically used only within the country where they were created—and tend to focus on different aspects of adaptation to local conditions or achieving specific farming objectives. In this context, we introduce a new framework for agroforestry tree species selection. Its goals are twofold: (i) to compile and organize the knowledge embedded in existing tree selection tools, and (ii) to offer an intuitive, user-friendly graphical interface—AgroforesTreeAdvice. This tool allows users to input local parameters such as soil type, climate, biotic factors, and farm-level or socio-economic constraints, alongside production goals (e.g., timber, fruits) and ecosystem service objectives (e.g., soil conservation, carbon storage). The unified system successfully integrates eight existing agroforestry DSS, improving their (i) findability by centralizing them in one location, (ii) accessibility through a standardized and user-friendly interface, (iii) interoperability by enabling API-based queries across all tools, and (iv) reusability for future DSS development. Finally, we present early user feedback from pilot deployments in three countries, highlighting the tool’s benefits and outlining next steps toward further harmonization of agroforestry databases.