Puppeteer and Playwright are the main open-source options nowadays, both solid for HTML → PDF once your print CSS is sorted. Don’t forget proper page breaks (break-before/after/inside) — e.g. break-after: page works in Chromium, while always doesn’t. For trickier pagination you can look at Paged.js, and I’d test layouts in Chrome/Edge before automating.
Shameless plug: I run yakpdf.com, a hosted Puppeteer-based service if you want to avoid self-hosting. https://rapidapi.com/yakpdf-yakpdf/api/yakpdf
Seconded. I went with C# + Playwright. I tried iTextSharp, iText, PDFSharp, and wkhtmltopdf, but they all had limitations. I had good results with Playwright in minutes, outside of tweaking the CSS like you mention.
I documented the process here[0] if anyone needs examples of the CSS and loading web fonts. Apologies for the article being long-winded – it was the first one I published.
[0] https://johnh.co/blog/creating-pdfs-from-html-using-csharp
Thirded, you can build this straight into your backend or into a microservice very easily.
You can also easily generate screenshots if that's more suitable than PDFs.
You can also easily use this to do stuff like jam a set of images into a HTML table and PDF or screenshot them in that format.
You made me realize that tractor feed roll paper would be really great for printed web pages, no page breaks! Kinda like reading scrolls of yore.