The method is based on the MOPAC software package, which is free for academic research, and the RDKit and OpenBabel toolkits, both of which are open source. The scripts that automate the calculation and the associated python codes are available on GitHub under the MIT open source license (see SI for more details). The method is relatively fast, requiring on the order of 1-10 minutes per molecule depending on the size of the molecule and the number of CPUs available. RegioSQM should therefore be of practical use to synthetic chemists and is freely available as a web-service at regiosqm.org.