PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
DocRaptor - As the only API powered by the Prince HTML-to-PDF engine, DocRaptor provides the best support for complex PDFs with powerful support for headers, page breaks, page numbers, flexbox, watermarks, accessible PDFs, and much more
PDFCrowd - Pdfcrowd is a Web/HTML to PDF online service. Convert HTML to PDF online in the browser or in your PHP, Python, Ruby, .NET, Java apps via the REST API.
PDF-XChange Editor - The smallest, fastest, most feature-rich PDF editor/viewer available
PDFSwitch - Convert any HTML document or URL to PDF with a single API request.
PDFGate - Convert HTML to pixel-perfect PDFs — fast, reliable, and API-first.