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.

Academus - Read research papers as interactive webpages

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

genei.io - AI-generated summaries for any article or research paper.

Memrise - Learn a new language with games, humorous chatbots and over 30,000 native speaker videos.

Arxiv Vanity - Read academic papers from arXiv as responsive web pages