Interactive Primer is described as 'Free, open-source “smart web pages” that teach maths, compsci and physics from the age of 5 to 105. One tree of knowledge you climb at your own pace, with animations, interactive diagrams, and randomized quizzes. No sign-up, no subscriptions, no ads' and is an website in the education & reference category. There are 2 alternatives to Interactive Primer, not only websites but also apps for Android, iPhone, iPad and Android Tablet. The best Interactive Primer alternative is Khan Academy, which is free.
Khan Academy is not-for-profit with the goal of changing education for the better by providing a free world-class education to anyone anywhere.
United States
Brilliant.org, also known as Brilliant, is a website and associated community that features problems and courses in mathematics, physics, quantitative finance, and computer science.
United States
