An online determination key for land- and freshwater snails and freshwater mussels of Central Europe in the German language (named ‘Naturportal Südwest - Weichtiere) is presented. It includes two modules for identifying the taxa: 1) a matrix of characters for all species and 2) a step-by-step determination key for pre-selected families. The key primarily aims to facilitate the determination of molluscs for beginners and amateurs and to provide easy access to the systematics of molluscs.