The Leiden Manifesto for research metrics outlines ten principles to guide research evaluation, aiming to prevent the misuse of metrics in assessing scientific performance. The document highlights the increasing reliance on data-driven evaluations, which can overshadow expert judgment. It discusses the proliferation of metrics, such as the h-index and journal impact factor, and their potential to distort research priorities. The manifesto warns against the overemphasis on global rankings and the misapplication of metrics in university promotions and funding decisions. It emphasizes the need for transparency, simplicity, and balance in the use of metrics, advocating for qualitative assessments alongside quantitative data. The principles stress the importance of evaluating research in the context of institutional missions, protecting locally relevant research, and ensuring open data practices. The manifesto also calls for regular scrutiny and updating of metrics to reflect changing research landscapes. It urges researchers and evaluators to hold each other accountable, ensuring that metrics serve as tools rather than goals. The text concludes with a call for a balanced approach that integrates robust statistics with sensitivity to the nature of research, emphasizing the need for high-quality data and informed decision-making in science.The Leiden Manifesto for research metrics outlines ten principles to guide research evaluation, aiming to prevent the misuse of metrics in assessing scientific performance. The document highlights the increasing reliance on data-driven evaluations, which can overshadow expert judgment. It discusses the proliferation of metrics, such as the h-index and journal impact factor, and their potential to distort research priorities. The manifesto warns against the overemphasis on global rankings and the misapplication of metrics in university promotions and funding decisions. It emphasizes the need for transparency, simplicity, and balance in the use of metrics, advocating for qualitative assessments alongside quantitative data. The principles stress the importance of evaluating research in the context of institutional missions, protecting locally relevant research, and ensuring open data practices. The manifesto also calls for regular scrutiny and updating of metrics to reflect changing research landscapes. It urges researchers and evaluators to hold each other accountable, ensuring that metrics serve as tools rather than goals. The text concludes with a call for a balanced approach that integrates robust statistics with sensitivity to the nature of research, emphasizing the need for high-quality data and informed decision-making in science.