In my usage at least, Calibre is an eBook library-manager, editor, and conversion tool... which has a so-so eBook reader attached that I mostly forget about. :D

In my usage at least, Calibre is an eBook library-manager, editor, and conversion tool... which has a so-so eBook reader attached that I mostly forget about. :D It's pretty essential for getting things onto the devices that I actually use to read, though.