FITS Preview is a lightweight and fast viewer for images in FITS format (Flexible Image Transport System) introduced by NASA and HEASARC.

The viewer is based on CFITSIO library and supports all standard monochromatic and color FITS image formats. It shows both an image (zoomed and stretched automatically, but manual correction of black and white point is available), an image metadata and histogram. The viewer can flip, rotate, debayer image and export images to JPEG format.

In addition to FITS format it supports also XISF (introduced by PixInsight) and INDIGO Raw (introduced by INDIGO Initiative).