Online FITS Viewer
Looking for an online FITS viewer that works without installing software? FITS Viewer lets you open, explore, and analyze FITS images directly in your browser — on any device, any operating system.
Simply drag and drop your .fits, .fit, or .fts file onto the page, and start exploring immediately. No account required, no file size limits, no ads.
Why use an online FITS viewer?
- No installation — works in Chrome, Firefox, Safari, and Edge
- Cross-platform — Windows, Mac, Linux, even tablets
- Instant access — open a FITS file in seconds, not minutes
- Privacy-first — files stay on your device, never uploaded
- Free forever — no hidden costs, no premium tier
What can you do with FITS Viewer?
Adjust colormaps
Switch between 15+ colormaps including Viridis, Magma, Inferno, Plasma, Heat, Rainbow, and more.
Control stretch
Apply Linear, Logarithmic, Square Root, or Arcsinh stretch. Use presets like 99%, ZScale, or Full.
Read WCS coordinates
See RA and Dec coordinates in real-time as you move your cursor over the image.
Analyze pixels
Probe individual pixel values or draw regions to compute statistics over an area.
View FITS headers
Inspect every FITS header keyword. Search and filter to find specific metadata.
Export results
Save your view as a PNG image, or export region statistics as CSV for further analysis.
How to view a FITS file online
- Go to fitsviewer.com
- Click “Open FITS file” or drag and drop your .fits file
- Explore your image with colormaps, stretch, and zoom controls
- Use probe mode and region analysis for detailed inspection
- Export as PNG or CSV when you're done
You can also click “Try a sample” to explore a bundled Eagle Nebula image without needing your own FITS file.