userscripts
Userscripts I've written or find helpful.
Userscripts are programs that can manipulate webpages and are typically used with a browser extension called a userscript manager.
Typically userscripts are used to improve or otherwise modify the UI on webpages.
More info here:
https://en.wikipedia.org/wiki/Userscript
Below are some links to different userscript managers:
Tampermonkey - https://www.tampermonkey.net/
Violentmonkey - https://violentmonkey.github.io/
Greasemonkey - https://www.greasespot.net/
Userscripts for ios/ipados - https://apps.apple.com/us/app/userscripts/id1463298887
Below are some userscript repositories:
Greasy Fork - https://greasyfork.org/
OpenUserJS - https://openuserjs.org/