OneNote Online - OneNote Online, part of Office Online, is the online version of Microsoft OneNote.
Okular - Okular is a universal document viewer based developed by KDE.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.