This document introduces attckr, an open-source toolkit for analyzing and visualizing ATT&CK incident data. It provides concise summaries of ATT&CK tactics and techniques from real-world incidents. Attckr includes functions for validating, normalizing, and visualizing ATT&CK data. It produces heatmaps and distributions of ATT&CK tactics to help analyze technology and workforce gaps. The toolkit is designed for use in R and can create interactive reports and dashboards from ATT&CK data without coding.