Vanilla JS
CSS
HTML
--------
Frameworks:
HTMX[0]
Tailwind CSS[1]
Cash[2]
Backend:
PHP
NodeJS
For quick mockups & landing pages:
Webflow[3]
Carrd[4]
Also some no-code SaaS solutions for dealing with tricky stuff like forms
[0] https://htmx.org/
[1] https://tailwindcss.com/
[2] https://kenwheeler.github.io/cash/
[3] https://webflow.com/
[4] https://carrd.co/