postcell.io — real-time feedback for Jupyter classes postcell.io keeps a programming class engaged by showing the instructor what every student is actually typing. Students run a Jupyter cell that starts with %%postcell; their code is sent to postcell.io, and the instructor's screen shows each student's latest attempt as it arrives, exercise by exercise. Instructors install the magic with pip install postcell, create a class, and hand out a small postcell.conf file. Students install the same package and put their name in it — they never create an account on any website. There is also a participation view, so you can see who answered which exercise over the term. You need to enable JavaScript to use the instructor pages. Help and setup instructions work without an account. Made by Shahbaz Chaudhary. Questions: info@postcell.io.