Khan Academy

Khan Academy is a completely free, nonprofit educational platform offering practice exercises, instructional videos, and a personalized learning dashboard. It covers K-12 math, science, computing, history, and test prep for SAT, LSAT, and more. Its mastery-based learning system ensures students grasp concepts before moving on. The primary audience is students, teachers, and parents.

It is funded by donations. It earns a high score for its exceptional social impact, quality content, and commitment to free, world-class education for anyone, anywhere, though its scope is more academic than professional.