SimCCS: An open-source tool for optimizing CO2 capture, transport, and storage infrastructure published in Environmental modelling and Software. Highlights Carbon capture and storage (CCS) is a critical climate mitigation technology. CCS infrastructure has to be cost-effectively deployed at a massive scale. CCS includes optimizing capture locations, storage sites, and the CO2 pipelines. SimCCS is a new CCS software package for research, industry, and policymakers.