I built this because I wanted to programatically generate invoices as well as automatically tailor my resume to jobs but had no good way of generating well-formatted PDFs. I ended up building a templating engine to Chromium rendering pipeline to generate PDFs, and due to the amount of engineering effort, turned it into a tool for others that might want to do the same. There's a built-in API (https://htmldocs.com/docs/documents) that you can call to turn JSON into PDFs in a single call.

htmldocs is different from other tools like Wkhtmltopdf and Weasyprint in that it uses Chromium to generate PDFs, meaning that it supports the most modern CSS features and there's minimal drift between the rendered HTML document and PDF.

Will also consider open sourcing if there's enough interest in the project!