Open .gii Files Online — Free GIFTI Viewer
Open GIFTI File Online — Free & Instant
No signup required. Works in your browser.
📁 Drag & drop your file here
or click to browse • Max 100MB
✅ Free • ⚡ Instant • 🔒 Secure • 💻 No install
What Is a .gii File?
A .gii file is a medical format known as GIFTI. GIFTI Surface Data This format is created by NIfTI and is widely used by radiologists and clinicians.
GIFTI files contain structured medical data that requires compatible software to open. With OpenAnyFile, you can view and reconstruct .gii files directly in your browser without installing any software.
How to Open .gii Files Online
- Visit OpenAnyFile GIFTI page
- Drag and drop your .gii file onto the upload area, or click "Browse" to select it
- OpenAnyFile automatically detects the GIFTI format using magic byte analysis
- View, analyze, and view and reconstruct your file contents in the browser
- Optionally convert to VTK, STL or download
Software That Opens .gii Files
.gii files are primarily created by NIfTI. In the medical space, you may encounter .gii files from third-party tools, online converters, or export functions. Regardless of the source, OpenAnyFile handles them all.
Open .gii on Different Platforms
- Windows: Use the original software or upload to OpenAnyFile for instant access
- macOS: Preview may not support .gii — use OpenAnyFile as a universal viewer
- Linux: Open-source alternatives exist, or use OpenAnyFile in any browser
- Mobile (iPhone/Android): OpenAnyFile works on all mobile browsers
Common .gii File Problems
Coordinate system ambiguity
Other common issues include: your OS not recognizing the file extension, the file appearing corrupted after download, or lacking the required software. OpenAnyFile bypasses all these issues with universal format detection.
Convert GIFTI to Other Formats
GIFTI files can be converted to 2 formats including VTK, STL.
Related Medical Formats
If you work with .gii files, you may also encounter these medical formats:
- ANALYZE (.hdr) — Open & convert .hdr files online
- Analyze 7.5 (.hdr) — Open & convert .hdr files online
- Analyze Image (.img) — Open & convert .img files online
- ANNOT (.annot) — Open & convert .annot files online
- ARTEMIS (.art) — Open & convert .art files online
- BDF (.bdf) — Open & convert .bdf files online
- BEDPOSTX (.bedpostX) — Open & convert .bedpostX files online
- BIDS (.json) — Open & convert .json files online
- BIF (.bif) — Open & convert .bif files online
- BRAINVISA (.arg) — Open & convert .arg files online
Popular GIFTI Conversions
Frequently Asked Questions
What is a .gii file?
A .gii file is a medical format called GIFTI. GIFTI Surface Data
How do I open a .gii file without installing software?
Upload your .gii file to OpenAnyFile. Our browser-based tool instantly detects and displays it — no downloads needed.
What program creates .gii files?
.gii files are typically created by NIfTI.
Can I convert .gii to another format?
Yes. OpenAnyFile converts .gii to VTK, STL.
Is it safe to open .gii files online?
Yes. OpenAnyFile processes files in a secure, isolated environment. Files are automatically deleted and all transfers use HTTPS.
Can I open .gii on my phone?
Yes. OpenAnyFile works on all mobile browsers including iPhone and Android.