LibreOffice Viewer - The Document Foundation provides a LibreOffice Viewer for Android.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Cisdem DocumentReader - Need to read mutiple windows documents on Mac? Cisdem Document Reader is the all in one solution to read WPD, WPS, XPS, OXPS, VISIO, DjVu, PDF, Winmail.dat files on Mac. Try it now!
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
OpenDocument Reader - OpenOffice Document Reader is an Android OpenOffice and LibreOffice Document Reader!
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.