BuiltWith - Find out the technology behind websites
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Competera - Competera is a price tracking tool for performance-oriented eCommerce retail and brands of all sizes worldwide.
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
Kompyte - Track & analyze competitors in real time.
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.