PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
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
HTML2PDF.fr - HTML2PDF is a HTML to PDF converter that allows the conversion of valid HTML 4.
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 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!