Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
Kahoot! - Kahoot! makes it easy to create, play and share fun learning games in minutes—for any subject, in any language, on any device.
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.
Mentimeter - a web-based polling tool for workshops, conferences & events
Memrise - Learn a new language with games, humorous chatbots and over 30,000 native speaker videos.
Sli.do - Slido is the ultimate Q&A and polling platform for live and virtual meetings and events. It offers interactive Q&A, live polls and insights about your audience.