XALT is a product to help sites understand individual users’ software needs, then leverages that understanding to help stakeholders conduct business in a more efficient, effective, and systematic way. It builds on work that is already improving the user experience and enhancing support programs for thousands of users on twelve supercomputers across the United States and Europe. XALT instruments individual jobs on high-end computers to generate a picture of the compilers, libraries, and other software that users need to run their jobs successfully. It will highlight the products researchers need and do not need, and alert users and support staff to the root causes of software configuration issues as soon as the problems occur. A key objective of this work is generating the information needed to improve efficiency and effectiveness for an extensive community of stakeholders including users, sponsoring institutions, support organizations, and development teams. Efficiency, effectiveness, and responsible stewardship each require a clear picture of users’ needs. XALT is an important step in the quest to achieve that clarity.