The digital teaching of medieval, and especially auxiliary, scientific skills has been going on for more than a decade. Nevertheless, the breadth and depth of the auxiliary sciences is making them difficult to present in their entirety. With ‘Ad fontes’, basic knowledge of skills needed to study the Middle Ages is imparted through interactive exercises. The e-learning platform was completely revised in 2018, allowing new technical possibilities to be realised while maintaining the strengths of its intuitive exercises. Additionally, crowdsourcing enterprises prove extremely valuable in the application of knowledge. After all, it is only possible to bring together knowledge of a particular field if collaborations are established across individual institutions and researchers.