Xodo - Try easy-to-use PDF tools that keep your documents safe. Work with your important files across all platforms and devices with the ultimate all-in-one document solution. Your productivity lives at Xodo!
Skim - Skim is a PDF reader and note-taker for OS X.
Casedo - A document collection, management, navigation, markup and search app for lawyers and investigators.
Altarsoft PDF Reader - Altarsoft PDF Reader is a simple to use PDF files management program that allows its users to view PDF files, encrypt the files and even annotate these files as well.
Haihaisoft PDF Reader - Haihaisoft PDF Reader is the name of a free to use PDF reader and printer that is extremely simple to launch.
MarginNote - A brand new e-reader to better study and digest your books