DCM file viewer
Open .dcm files online for free. A DCM file viewer that runs in your browser, handles files with no extension and never uploads your data.
What it does
A .dcm file is a medical image, and Windows and macOS both refuse to preview it. Double-clicking usually does nothing at all, or opens a dialog asking which program to use.
This viewer opens .dcm files directly. It also opens the same files when they have no extension, which is what happens on a lot of hospital discs, and it copes with a folder full of them.
Opens .dcm regardless of naming
Extension or no extension, the file is identified by its contents rather than its name.
Handles folders and archives
Select every file in a folder, or drop the ZIP straight in.
Full image controls
Window, contrast, zoom, pan and rotation, plus PNG export.
Tells you when a file is not what you think
A clear message when the file is not DICOM, is damaged or uses an unsupported compression.
How to use it
Locate the .dcm files
On a hospital CD they are usually inside a folder called DICOM or IMAGES.
Select them all
You can add the whole folder at once, or the ZIP you downloaded.
Browse the images
Step through the slices and adjust the image until it reads clearly.
Do something with it
Export a picture, check the metadata or remove the personal details.
When people use it
Double-clicking a .dcm did nothing
The most common reason people look for a DCM viewer in the first place.
A colleague sent you a .dcm by email
Open it immediately without asking them to convert it first.
You want to check a disc before an appointment
Confirm the files are readable and the study is complete.
Supported files
- Uncompressed DICOM (implicit and explicit VR, little and big endian)
- RLE lossless compression
- JPEG baseline and extended, decoded by your browser
- Files with a .dcm extension, and DICOM files with no extension at all
- ZIP archives containing a whole study or several series
Limitations
- JPEG Lossless, JPEG-LS, JPEG 2000 and deflated transfer syntaxes are not decoded — they need heavy codecs we deliberately do not ship. You will get a clear message instead of a blank screen.
- This is a technical tool. It does not read your scan, does not look for findings and does not produce any diagnosis.
- Very large studies of several hundred megabytes may be slow, because all the work happens on your own machine.
Privacy and security
Processed in your browser — nothing is uploaded
Your files never leave your device. Everything runs inside your browser using JavaScript — there is no upload, no server copy and no queue.
Because nothing is uploaded, there is nothing for us to store or delete. Closing the tab removes the files from memory.
We never put file names, patient identifiers or metadata values into analytics or logs. Product events only count how many files were opened.
If you later choose the paid AI explanation, that is a separate, explicit step: you decide which files to attach and nothing is sent until you confirm.
Frequently asked questions
What program opens a .dcm file?
Any DICOM viewer. This page is one and needs no installation — but desktop options such as Horos, Weasis or RadiAnt also exist if you prefer software on your machine.
Why will Windows not preview my .dcm file?
Windows has no built-in DICOM support. The format is designed for medical equipment, not for general-purpose photo viewers.
My files have no extension at all. Is that normal?
Completely normal. Hospital discs often store files as IM_0001 or similar. This viewer reads the file header rather than trusting the name.
Can I convert a .dcm to something I can email?
Yes — use the DICOM to JPG or DICOM to PDF converter, which shares the same engine as this viewer.