Последовательностные узлы is an Android application designed as an additional teaching aid for students of the "Fundamentals of Digital Technology" course. The app covers the main types of sequential devices, including trigger elements, registers, and counters of various modifications. The app is a comprehensive learning tool that provides theoretical knowledge of the principles of functioning, conventional graphic symbols, truth tables, input, and output signals of digital devices. It is also useful for those who want to self-learn the basics of digital electronics. The app features a program model - an emulator, which allows the user to visualize the algorithm of the functioning of the selected device through interactive interface elements. The app also provides brief theoretical information, including definitions, pin assignments, and truth tables, describing the operation of the device in a formalized manner.