As of version 02.2021 (March 2021), P&D contains 77,130 compounds with 4,466 labelled as chemical probes by their sources used for this study. However, these should not be considered equivalent in a canonical sense because they have been generated by divergent approaches. By analysing the structures and associated metadata, we have tried to establish a high-quality subset based on the probe origin and by the application of scoring schemes. In addition, where the data allow plausible assignments, we have compiled target coverage.