The negative impact of alien species is recognised as a major threat to biodiversity. However, in the absence of evidence-based impact indicators that follow the Findable, Accessible, Interoperable, and Reusable (FAIR) Data Principles with standardised workflows, the impacts of alien species are not systematically estimated over time, a major gap for policy. We develop the impIndicator R package, using an open-source workflow for computing impact indicators of alien species, by combining occurrence data from the Global Biodiversity Information Facility (GBIF) with Environmental Impact Classification for Alien Taxa (EICAT) assessments.