Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
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.
HTML PDF API - Easily generate PDF documents from HTML code with our powerful API
PDFSwitch - Convert any HTML document or URL to PDF with a single API request.
HTML2PDF.fr - HTML2PDF is a HTML to PDF converter that allows the conversion of valid HTML 4.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request