https://playanypage.com/
Javascript bookmarklets that let you turn any page into interactive games: breakout, snake, etc.
https://playanypage.com/
https://perthirtysix.com/how-the-heck-do-qr-codes-work
Explainer about how QR codes work.
Posted in genres
https://ciechanow.ski/archives/
A site full of interesting explainers of real world engineering and technology designed for the layman, including many interactive javascript demonstrations: how naval architecture (keeping ships afloat) works, how GPS works, fascinating facts about the moon, and much more. Worth a browse.
Posted in genres
https://ciechanow.ski/gps/
An exhaustive explanation for the layman of how GPS works, including numerous interactive javascript demonstrations.
Posted in genres
https://www.ericweinhoffer.com/blog/the-whitworth-three-plates-method/
A mechanical engineer's page about an old (pre-1830s) mechanical method for producing microscopically flat surfaces.