Apache PDFBox - The Apache PDFBox™ library is an open source Java tool for working with PDF documents.
Documents by Readdle - A central hub for all your files.
iTextPDF - iText offers flexible tools for PDF creation, editing and inspection.
Documents Pro 7 - The ultimate all-in-one mobile office suite for the iPhone and iPad with 8 premium apps in 1.
IronPDF - SDK for creating and editing PDFs.
GoodReader - With GoodReader on your iPhone, iPod Touch or iPad, you can read virtually anything, anywhere.