The dynamic progress in the multi-step continuous-flow synthesis of active pharmaceutical ingredients is part of the current industrial revolution. The recently implemented examples are the forerunners of safer and more sustainable pharmaceutical manufacturing. These systems utilize interconnected flow apparatuses, integrated with in-line work-up, purification and analysis. Challenging targets call for customized, flow-oriented designs to establish novel, telescoped continuous-flow sequences. In this review we focus on these efforts towards the development of uninterrupted continuous-flow systems.