A fast, secure, browser-based tool to inspect, edit, add, and export astronomical FITS (
.fits,.fit,.fts) header metadata directly on client-side.🔗 Online Tool: https://abctool.info/fits-header-editor-online/
Traditionally, viewing and editing astronomical FITS metadata required installing heavyweight desktop software (such as SAOImage DS9, AstroImageJ, PixInsight) or running Python scripts with astropy.io.fits.
FITS Header Editor Online brings full FITS header viewing and editing capabilities directly into your web browser:
- 100% Client-Side & Private: Files are parsed and processed purely inside your browser. No astronomical data is ever uploaded to any external server.
- Zero Installation: Works out of the box on any device (Windows, macOS, Linux, tablet) with a modern web browser.
- Real-Time Header Editing: Add, update, reorder, or delete 80-character standardized FITS cards in real time.
- Export Flexibility: Save and download modified
.fitsfiles instantly, or export metadata to JSON and TXT formats.
Open FITS Header Editor Online. You will see the initial upload screen:
- Select or Drop File: Drag and drop your
.fits,.fit, or.ftsfile into the dashed box, or click Select FITS File. - Sample File: Want to try it first? Click Load Sample FITS to load pre-configured astronomical sample data (
13838SgrA.fits) with one click.
Once loaded, the full interactive header editor table appears:
- File Summary: The top banner displays essential file info, including the file name, file size, total number of header cards, and HDU type (e.g.,
Primary HDU). - Instant Search: Use the search input (
Search keywords, values, comments...) to quickly locate specific cards by keyword name, value, or comment. - Category Filters: Filter cards by standardized functional categories:
- All: View all existing cards in order.
- Target & Coord: Object names, RA/DEC coordinates, equinox, etc.
- Camera & Optics: Exposure time, gain, filter name, focal length, pixel dimensions.
- WCS Coordinates: Astrometric projection standards (CRVAL, CRPIX, CD matrix).
- Structural: Standard FITS structural cards (SIMPLE, BITPIX, NAXIS, EXTEND).
The editor table offers full granular control over each card:
- Edit Values & Types: Update values with dedicated input widgets. Boolean values feature intuitive dropdown toggles (
T (True)/F (False)), while strings and numeric values can be adjusted inline. - Quick Helpers: Click commonly used astronomical shortcut buttons to immediately inject essential keywords:
+ OBJECT(Target name)+ EXPTIME(Exposure time in seconds)+ FILTER(Optical filter name)+ BAYERPAT(Bayer color pattern)+ GAIN(Sensor gain)+ FOCALLEN(Telescope focal length)+ PIXSIZE(Pixel physical size)+ OBSERVER(Observer / Astrophotographer name)
- Custom Keywords: Click + Add Keyword to create any custom FITS keyword card with custom types, values, and comments.
- Reorder & Remove: Use the up/down arrows (
↑,↓) on the right to adjust card order, or click (✕) to delete unnecessary cards. - Reset: Click Reset at any time to discard unsaved edits and restore the original file state.
When your edits are complete:
- Save & Download FITS: Click Save & Download FITS to repackage the updated header with the raw binary image data into a clean, compliant
.fitsfile and download it to your device. - Export JSON: Export all header cards as a structured JSON key-value document for scripting and automation.
- Export TXT: Export the clean standard text representation of the FITS header cards.
| Feature | Details |
|---|---|
| Supported File Extensions | .fits, .fit, .fts |
| HDU Support | Primary HDU & Standard Image Extensions |
| Standard Compliance | Standard 80-column FITS card format (NASA / IAU FITS standard) |
| Security & Privacy | 100% In-browser execution (WebAssembly / JavaScript); no cloud uploads |
👉 Launch tool directly in your browser: https://abctool.info/fits-header-editor-online/