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
Zamzar - Free conversion online of many type of documents (images, text, video, audio...
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.
Vertopal - Vertopal is an online platform for converting computer files to a variety of file formats.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
FreeConvert Audio Converter - FreeConvert offers a highly efficient Audio Converter to help you convert them from one format to another.