Calibre is a powerful and easy to use e-book manager
Thorium Reader
Thorium Reader is an easy to use EPUB reading application.
Sigil
Sigil is a multi-platform EPUB ebook editor .
MComix3
MComix se yon visualiseur imaj ki fasil pou itilize, ki ka personnalisable. Li fèt espesyalman pou okipe liv komik (tou de komik Lwès ak manga) epi li sipòte yon varyete fòma veso (ki gen ladan CBR, CBZ, CB7, CBT, LHA ak PDF). MComix se yon fouchèt Comix.
CoolReader
Cross platform open source e-book reader.
Foliate
A simple and modern eBook viewer
Bookworm
Read the books you love without having to worry about different format complexities like epub, pdf, mobi, cbr, etc.