 Research-performing organizations manage their funds and expenses while offering high-quality research outcomes that are evaluated by funders and policymakers and diffused via research infrastructures. But how can research organizations keep track of the money spent on open access publications, discover cost trends across publishers, e-journals, and books or monographs, align their strategy, and achieve better results? OpenAPC is a service that collects information on APCs and VPCs from research-performing organizations and provides them with personalized visualizations and reports. How does OpenAPC do that? By aggregating and normalizing cost data and bibliographic data on open access journal articles, open access books, and articles published under transformative agreements and giving access to these datasets to all interested parties. OpenAPC is a service for research-performing organizations, research infrastructures, funders and policymakers. OpenAPC is supported by more than 394 data-contributing institutions and top universities to monitor and visualize open access publishing costs. With OpenAPC, anyone can publicly view organizations' open access costs, but only authorized members receive their personalized detailed report privately. With OpenAPC, you can publicly view, filter, export, or embed the sum of costs per publisher and per journal, the number of articles per publisher, the mean cost per publisher, the standard cost deviation per publisher, the percentage of costs per publisher, along with a combination of open-air services, it can provide indicators and impact measures, like return on investment. OpenAPC. Evidence-based metrics for rational decision making.