Interactive visualizations for different topics from physics and mathematics. Includes trigonometry, polynomial regression, and Bézier splines
https://visualize-it.github.io/
And a shameless plug — a collection of interactive tutorials, demos, and quizzes about mathematics, algorithms and programming.
https://wordsandbuttons.online/
This is cool but this is the worst UI ever and makes no sense. The tutorial resets it each time and its not clear how to actually visualize the animation at the same time as learning about it
http://www.cs.usfca.edu/~galles/visualization/Algorithms.htm...
https://bost.ocks.org/mike/algorithms/