FITS File Extension

Flexible Image Transport System Format

File Type fits
Popularity
4.6 (41 vote)
Application AVIS - FITS Viewer
Category Graphics Files
Format Binary

What is a FITS file?

Flexible Image Transport System Format, identified by the FITS extension, is a Graphics Files type and includes 556 files.

FITS file support extends to various operating systems, including Windows, Mac OS and Linux. If you need to open a FITS file, you can use one of 4 programs, such as AVIS - FITS Viewer, XnView and ImageJ.

Windows

Mac OS

Linux

Online Services

Picture Resize Genius

How to open a FITS file?

If you’re having difficulty opening a FITS file, it is often due to not having the correct software. To solve the problem, choose a compatible program from the list. Then follow the link to the official developer site, download the software, and install it on your device.

When it comes to opening and working with FITS files, AVIS - FITS Viewer, XnView and ImageJ are the top choices for users. If you need the newest version of AVIS - FITS Viewer, just access the MSB website. From there you can download the installer compatible with all systems.

Following installation, FITS files should be automatically opened with AVIS - FITS Viewer.

Set AVIS - FITS Viewer as the default FITS program

Changing Default Programs in Windows

Right-click your FITS file, then navigate to the "Open With" option and click "Choose Another Application" to continue;
In the pop-up window, select the AVIS - FITS Viewer application;
Check the "Always use this application" checkbox, and then click "OK" to apply the selected application as the default for opening FITS files.

Change Default Program on Mac

Right click or Control + left click on the desired FITS file;
Select "Open in application" and click "Other";
Look at the bottom of the window, where you will see the "Enable" menu. "Recommended Programs" will be selected as the default option;
Within this menu select "All Programs" and navigate to AVIS - FITS Viewer. Check the box next to "Always open in app" to make sure it’s the default option.

Solve problems with FITS files

When issues arise with FITS files, they can generally be fixed with small software tweaks. Use the troubleshooting tips below to help resolve them.

What can lead to sudden AVIS - FITS Viewer crashes?

AVIS - FITS Viewer crashes can occur due to outdated software versions. To mitigate this, install the latest updates for MSB products.

Restarting your computer will solve many common problems, which is why it’s the first thing you should do before changing any settings related to the software.

What is the recommended approach to repair a damaged FITS file?

Open the damaged FITS file with a recovery program, and then select the "Repair" menu item to start the repair process. Allow the recovery process to complete, which will automatically repair the damaged graphics files.

What are the telltale signs of a corrupt FITS file?

Common indications of damaged FITS graphics files are:

Unexpected expansion of the total size of the FITS file;
Opening the file in AVIS - FITS Viewer or other programs causes them to hang or crash;
Opening the file results in an error or a failed attempt;
While working with the file, error messages appear;
Editing the archive in ImageJ results in slow or unresponsive behavior;

How to edit a FITS file?

To edit FITS files, it is essential to install software that supports not only viewing but also editing the graphics files. Online FITS editors provide limited functionality compared to full-featured software for Flexible Image Transport System Format.

List of Top FITS editors 2026

Taking into account the provided details, we have prepared a list of FITS editors that match your needs.

FITS Editor Software	Developer	Platforms	Overall Rating
ImageJ	Wayne Rasband	Windows, Mac OS, Linux	4.6 out of 5 (36 reviews)

Convert to and from FITS

If handling a FITS file is problematic, consider converting it to alternative formats such as JPG, JPEG, BMP, FTS or other supported types.

Keep in mind that converting a FITS file may introduce some limitations, but the original format can often be restored.

Using offline applications such as XnView and Picture Resize Genius, you can convert FITS files to various formats without losing data quality.