FactSage is an extensive software and database suite for thermochemical analysis, created in collaboration by Thermfact/CRCT based in Montreal, Canada, and GTT-Technologies located in Aachen, Germany. Launched in 2001, it combines the capabilities of the FACT-Win/FAC*T and ChemSage/SOLGASMIX thermochemical tools, which stem from over two decades of joint research. This software features a collection of modules for information retrieval, database access, calculations, and data manipulation that cater to a wide range of pure substances and solution data. It serves a diverse array of users, including those in industry, government, and academia, across disciplines such as materials science, pyrometallurgy, hydrometallurgy, electrometallurgy, corrosion science, glass technology, combustion, ceramics, and geology. Users can tap into thermodynamic data for numerous compounds and have access to evaluated databases for hundreds of solutions, which encompass metals, oxides, slags, mattes, salts, and various aqueous solutions. Overall, FactSage stands as a vital tool for professionals seeking reliable thermochemical information and analysis.