By default, all software supports multiple file extensions. FITS Viewer supports at least 1 different file extensions. The basic files that FITS Viewer supports are .FTS. However, not all of the extensions listed on the list are always used to save the effects of work in FITS Viewer. Very often, files with such extensions are used as source data files used by FITS Viewer.
FITS Viewer 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 FITS Viewer and try to save it in another file format, also supported by FITS Viewer.