Pdf.to - Convert PDF to Word, Excel, JPG, & from. Also compress PDF
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
Anvil PDF Filling API - The easiest way to programmatically populate any PDF
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.
RatherListen - Convert URLs, PDFs, & photos to clear spoken audio
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request