Ciechanowski's work (check Gears and Curves as good examples, but all of them are good) https://ciechanow.ski/archives/

Interactive linear algebra book https://textbooks.math.gatech.edu/ila/

Visualizing quaternions https://eater.net/quaternions

Another quaternions visualization tool that reminded me that a few years ago many sites were full of java applets that were the first "explorables". Sometimes I still stumble upon old university websites that leave some space for the applet but it never loads. Sad stuff

https://quaternions.online/

Some tools to make them:

https://github.com/ManimCommunity/manim

https://p5js.org/

https://processing.org/