PrairieLearn
PrairieLearn is an online problem-driven learning system for creating homeworks and tests. It allows questions to be written using arbitrary HTML, JavaScript, and Python, thus enabling very powerful questions that can randomize and autograde themselves, and can access client- and server-side libraries to handle tasks such as graphical drawing, symbolic algebra, and student code compilation and execution.
Paid hosting and support: https://www.prairielearn.com/