A directory of several websites where you can study various things online.
MOOCs (Massively Open Online Courses) run by different universities across the world. Most are completely free.
Like Coursera, FutureLearn offers MOOCs run by many different universities on various topics.
More free courses on a range of topics.
More free courses, though mainly on creative subjects.
A Telegram channel containing a course in military tactics.
Free access to several MIT courses, with lectures, assignments and exams.