So Creddle doesn't natively export PDFs, but rather relies on the browser to print the page as a PDF. At the very least, the site exports the resume to static HTML during this process in order to strip away unneccessary attributes and elements before printing.

It's a short-term solution. If I can recall correctly, I tried both wkhtmltopdf and PhantomJS and was able to succesfully export maybe 60-70% of resumes properly. But I ran into numerous differences with fonts and spacing that sometimes caused weird page or section breaks. I ended up scrapping that method in favor of working on DOCX exporting, because at least there was some method of printing a PDF, even if it was a workaround.

I do want to go back and re-explore PDF exporting, but other requests are taking priority at the moment. I do have guided help on printing as a PDF for a few browsers and OSs in the "Help" section.

Not sure how Creddle is doing it, but on my weekend project https://resumejoy.com (basic service is free), I use wkhtmltopdf. It's a little fiddly, but handles webfonts and most any CSS you throw at it.

Generating PDFs programmatically for a well defined problem like that is not as gard as you think. There are libraries to easily generate PDFs in most languages.