Hemmingway App – Free online service. You paste your writing in and it helps identify over-long and complicated sentences, unnecessary words, passive voice, etc.

Goconqr – Free, but you can pay premium to get rid of ads. An online learning community allows you to customize your experience as a student, employee, or educator. There are groups to join and discuss topics, or you can work alone. It has tools to make flashcards, mind maps, side sets, notes, flow charts, and quizzes. It is highly intuitive and easy to use. 

Quizlet – Free. It lets you make your own flashcards, and then automatically generates games with them to help you study. You can also search for card packs that other users have made, and you can often find things relevant to your class, or even from other people who have taken your class.

Marinara Timer – Free. An online timer tool that has presets or you can customize your own. It is for the Pomodoro Technique of studying

Schooltraq – Free. A digital planner, much like iStudiez Pro, but it synchronizes between the phone and the computer.

IStudiez Pro – Free. A phone app that lets you add courses, assignments, and due dates, then sends you class and project reminders. I started using it this semester to keep track of assignments. It also had note-taking features, but I cannot say from experience if they are any good.