the web app i.e the front end part is next.js and typescript mostly, the landing page is built using astro.js, and the back end is heavily python, flask and some javascript for web-to-pdf and markdown-to-pdf, the rest is mostly python
A neat trick to convert HTML to PDF in a browser environment is to open a new browser window, load the HTML in it, and call print() on it, like here: https://stackoverflow.com/a/33890644/5821. May be OK for an internal tool.