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.
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
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
Docamatic - Easily generate high quality PDF documents from HTML or templates. Fast, scalable and privacy focused PDF generation API.
PDF my URL - PDFmyURL turns any webpage or even complete website into PDF. Use our rest API in PHP, .NET, Ruby, Perl or any other programming language. Or convert webpages or even full websites directly in the browser!