Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.

Blinkist - Key insights from 6,000+ bestselling books and podcasts

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.

Instaread - Read or hear key takeaways of any book in minutes

Brainscape - Find, create, and study SMART FLASHCARDS on any device. DOUBLE your learning speed using the most effective study system on the planet. Keep all your content in sync across Brainscape's website and your Android devices.

wits.io - Weekly book summaries recommended by founders and makers