Abstract The Carbohydrate-Active enZYme database (CAZy; www.cazy.org) has been providing the reference classification of carbohydrate-active enzymes (CAZymes) for >30 years. Based on literature survey, the sequence-based families of CAZymes are enriched with functional data by using the International Union of Biochemistry and Molecular Biology Enzyme Commission (EC) number system. However, this system was not developed to search or compare functional information. To better harness functional information, we have developed CAZac (CAZyme activity descriptor), a multicriterion system that describes CAZymes’ mechanisms, glycosidic bond orientations, subsites and inter-residue connectivities. This new system, implemented for glycoside hydrolases, glycoside phosphorylases, transglycosidases, polysaccharide lyases and lytic polysaccharide monooxygenases allows complex searches in the CAZy database to uncover the evolution of substrate specificity and mechanisms of CAZymes across families.