NIfTI MRI Viewer
Free NIfTI Viewer Online
Open, view, and analyze medical NIfTI (.nii, .nii.gz) files instantly. 100% secure, zero-upload client-side processing. Adjust windowing, pan, zoom, and analyze neuroimaging data safely.
Secure Web-Based NIfTI Player
Drop .nii or .nii.gz file here
or click to browse from your device100% HIPAA Compliant Client-Side Rendering. No data leaves your browser.
How to Open NIfTI Files (MRI & fMRI)
Directly parse NIfTI headers and draw 3D/4D diagnostic image arrays locally in browser memory without sending medical data to any external server.
1. Select Your Brain Scan
Select or drag & drop your .nii or .nii.gz file into the secure ingestion dropzone above.
2. Inspect Neuro Metadata
Verify parsed volume dimensions, voxel spacing, and affine transformations.
3. Navigate 3D Slices
Use the slider or mouse wheel to navigate through axial, sagittal, and coronal planes instantly.
Zero-Footprint & HIPAA Compliant Features
Patient privacy is our absolute priority. By rendering medical scans locally inside your browser memory sandbox using nifti-reader-js and HTML5 Canvas, sensitive medical images never leave your device.
Zero Server Bandwidth
Your large medical scans (fMRI slices) stay inside your local browser. Complete offline compatibility, absolute privacy.
NIfTI Header Decoding
Decodes NIfTI-1 and NIfTI-2 tags to extract volume dimensions, pixel spacing, datatype, and qform/sform affines.
Interactive Slicing
Instantly reconstruct and scroll through 3D volumes in Axial, Sagittal, and Coronal views directly in memory.
Frequently Asked Questions about NIfTI Files
What is this Free NIfTI Viewer Online?
It is a secure, 100% client-side web utility designed to open and inspect Neuroimaging Informatics Technology Initiative (.nii, .nii.gz) files. By decoding files locally within your browser context, patient data and scan volumes are protected with absolute privacy.
How does client-side rendering work for .nii files?
Our tool parses the binary headers and 3D data arrays of the NIfTI file using local JavaScript codecs (nifti-reader-js). The data is unzipped using local fflate codecs if it is compressed (.nii.gz). Pixel values are mapped and rendered directly onto an HTML5 canvas element.
How do I change the viewing plane?
Once a file is loaded, you can use the Axial, Sagittal, and Coronal buttons below the main viewer to instantly re-slice the 3D volume along different anatomical planes.
Can I use this tool offline?
Yes. Once the page is loaded, the entire decoding and interactive pipeline operates locally. This is ideal for research computers that do not have dedicated neuroimaging software installed.
How NIfTI Viewer Works
Our high-performance online utility runs entirely client-side, processing your files securely and instantly inside your web browser. For related functions, you can also use our All Medical Tools and DICOM Viewer utilities.
Upload NIfTI
Step-by-step interactive processing designed for simple, fast, and high-fidelity execution.
View Brain
Step-by-step interactive processing designed for simple, fast, and high-fidelity execution.
3D Visualization
Step-by-step interactive processing designed for simple, fast, and high-fidelity execution.
Neuroimaging Support
Designed for professional results, privacy, and maximum compatibility across all modern desktop and mobile browsers:
.nii Files
Full digital precision and optimized performance with zero server-side latency or external data transfers.
.nii.gz Compressed
Full digital precision and optimized performance with zero server-side latency or external data transfers.
Brain MRI
Full digital precision and optimized performance with zero server-side latency or external data transfers.
Medical Imaging
Full digital precision and optimized performance with zero server-side latency or external data transfers.