Open FITS files online
FITS is the astronomy standard for telescope and satellite images and tabular data.
Drop a FITS file to open it
or click to choose — everything stays on your device
Choose file🔒 100% private — files never leave your browser
What is a FITS file?
FITS is the astronomy standard for telescope and satellite images and tabular data. The .FITS extension identifies a Flexible Image Transport System file, which is served with the application/fits media type. You can open it here instantly — drop the file into the box above and it renders in your browser. Nothing is uploaded.
Besides this free online viewer, you can open FITS (astronomy) files in desktop apps such as SAOImageDS9, FITS Liberator — but here all you need is a web browser.
Quick facts
| Format | FITS (astronomy) — Flexible Image Transport System |
|---|---|
| File extensions | .fits .fit |
| MIME type | application/fits |
| Developer | NASA / IAU |
| Category | Specialised |
| Also opens in | SAOImageDS9, FITS Liberator |
How to open a FITS file online
- Click Choose file above, or drag your FITS file onto the box.
- The right viewer loads automatically and renders your file.
- Read, scroll or page through it. To open a different file, choose Open another file.
100% private — files never leave your browser.
Libraries used to render FITS in the browser
This viewer is built entirely with open-source JavaScript that runs in your browser:
Frequently asked questions
What is a .FITS file?
A .FITS file is a Flexible Image Transport System, identified by the application/fits media type. You can open and read it instantly in the viewer above without installing anything.
What programs open FITS files?
On the desktop, FITS files typically open in SAOImageDS9, FITS Liberator. Online, this page opens them in any modern browser — nothing to download.
Is it safe to open my FITS file here?
Yes. The file is read and rendered entirely by JavaScript inside your own browser. It is never uploaded to a server, so nothing leaves your device.
Do I need to install anything to view a FITS file?
No. There is nothing to install and no account to create. Open the page, drop your file, and it displays instantly.
Does it work on my phone or iPad?
Yes. The viewer is fully responsive and works in modern mobile and tablet browsers such as Safari and Chrome.
Is there a file size limit?
There is no hard limit, but very large files depend on your device’s memory. Big files are processed in the background so the page stays responsive.