GTT-Technologies (GTT Gesellschaft für Technische Thermochemie und -physik mbH) is a German company specialized in technical thermochemistry since 1983, with roots at the Materials Chemistry chair of RWTH Aachen University. It develops a family of thermodynamic software (FactSage, ChemApp, ChemSheet), supplies thermochemical data and databases, provides consulting and calculation services, and offers training courses to metallurgists, materials scientists and process engineers in industry and academia.