pdflayer - Free, powerful HTML to PDF API supporting both URL and raw HTML conversion. Unlimited document size, lightning-fast and compatible PHP, Python, Ruby, etc.
Orderwerks - Orderwerks is a B2B Online Ordering System For Manufacturers, Distributors and More.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
html2pdf.app - HTML to PDF conversion API
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
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