By default, all software supports multiple file extensions. FBReader supports at least 6 different file extensions. The basic files that FBReader supports are .EPUB. However, not all of the extensions listed on the list are always used to save the effects of work in FBReader. Very often, files with such extensions are used as source data files used by FBReader.
FBReader can be used to convert file formats between the file extensions listed below. You can open a file with one of the file extensions below via FBReader and try to save it in another file format, also supported by FBReader.