DICOM Medical Image Viewer

Online DICOM Medical Image Viewer lets you open medical imaging data directly in your browser without installing any software. It supports imaging folders (including DICOMDIR), zip archives, .dcm files and NIfTI (.nii / .nii.gz) research data - ideal for patients reviewing imaging data from the hospital, radiologists quickly reading studies on any computer, medical students learning cross-sectional anatomy, and researchers browsing NIfTI datasets. All parsing is done locally in your browser, so your files are never uploaded to any server, making the tool especially suitable for privacy-sensitive use.

What is DICOM?

DICOM (Digital Imaging and Communications in Medicine) is the international standard for medical imaging, used to store images from CT, MRI, DR, PET and other examinations. Unlike jpg/png photos, a single exam usually consists of dozens to thousands of .dcm files organized into folder-based series, with a DICOMDIR index describing the relationship between patient, study and series. Each file carries not only pixel data but also metadata such as patient information, scan parameters and window presets. Because of this special format, regular image viewers cannot open these files - which is why a dedicated medical image viewer is needed. NIfTI (.nii / .nii.gz) files, commonly used in research, are another pure-image format that ordinary software cannot read directly either.

Key Features

• Multiple ways to load data: drag and drop a folder or archive onto the page, or click "Choose imaging folder" / "Choose zip, .dcm or .nii". Password-protected archives are detected and you will be asked to extract them first.
• Study and series management: a sidebar groups images by study and series, so multi-series scans are easy to switch between, with modality and slice counts shown at a glance.
• Three-plane viewing: switch between axial, coronal and sagittal views instantly and scroll through slices with the mouse wheel or touch gestures; a hint appears when a series is too thin for a given plane.
• Window width / level adjustment: tune WW and WL with sliders, numeric inputs, or by dragging directly on the image; CT studies include common clinical presets such as lung, bone, brain and soft tissue windows.
• View controls: center-stable zoom, 90-degree rotation, horizontal/vertical flip, grayscale inversion, and one-click reset.
• Pixel reading: hover over the image to read the CT value (HU) at the cursor position for density inspection.
• Patient privacy protection: patient name and date of birth are masked by default and can be revealed locally only when needed.
• Export and fullscreen: export the current slice as a PNG image, or enter fullscreen mode for better viewing.

How to Use

1. Copy the imaging data into a folder on your computer (extract any archives first);
2. Click "Choose imaging folder" and select that folder, or simply drop a zip archive, .dcm file or .nii file onto the page;
3. Pick a series from the sidebar and wait for it to load (progress is shown for large datasets);
4. Scroll to browse slices, switch planes, and use presets or manual sliders to adjust the window.

Use Cases

• Patients or family members reviewing imaging data from the hospital without installing dedicated viewing software;
• Radiologists and physicians quickly reading DICOM series on any computer;
• Medical students learning cross-sectional anatomy in teaching sessions;
• Researchers browsing NIfTI-format imaging data.

FAQ

Q: Is this tool free? Do I need to install any software?

A: Yes, it is completely free and requires no installation. Just open this page in a modern browser on your computer or mobile device; all processing happens locally.

Q: Which imaging formats are supported?

A: Imaging folders (with DICOMDIR), zip archives, .dcm / .dc3 / .ima files, and .nii / .nii.gz research data. If a series uses a compression format that is not yet supported (such as JPEG 2000 or JPEG Lossless), the page will tell you and suggest dedicated software.

Q: Are my files uploaded to a server?

A: No. All parsing is done locally in your browser. Your files never leave your device and are never uploaded or stored.

Q: Is patient information displayed?

A: The patient name and date of birth are masked by default. They are only revealed locally when you click "Show details" to verify the study.

Q: Why won't an archive open?

A: Password-protected archives must be extracted first. Very large archives (roughly over 900MB) may exceed browser memory limits - we recommend extracting them on your computer and then opening the folder instead.

Q: Can I save an image?

A: Yes. Click "Export slice" to save the current slice as a PNG for archiving or sharing.

This viewer is for reference only and is not intended for diagnosis. Always follow your doctor's report.