Sumatra PDF is PDF reader and writer for Windows.

Okular is a universal document viewer based developed by KDE.

TagSpaces is an open source data manager and file navigator. It helps organize files on local drives by adding tags to files.

EPUB is an e-book file format with the extension .epub that can be downloaded and read on devices like smartphones, tablets, computers, or e-readers.

Calibre is an Ebook management software.

FBReader is a free ebook reader. Main ebook formats: ePub (including main features of ePub3), Kindle azw3 (mobipocket), fb2(.zip).

Aldiko is an e-book reader application for the Android and iOS operating systems.

Adobe Digital Editions (ADE) is an ebook reader software.