Weasis: Free DICOM viewer
A free / libre DICOM viewer for medical imaging
Weasis is a powerful, multifunctional, open-source DICOM viewer for both standalone and web-based use. From routine reading to AI-assisted review and quantitative imaging, it is engineered for seamless integration with PACS, VNA, and DICOM workflows in hospitals, multicenter research trials, and patient-facing portals.
Find your way around
🩺 Clinicians & end users
Open studies, drive the 2D / MPR / 3D viewers, measure, annotate, share findings.
🛠 Integrators & administrators
Connect Weasis to your PACS, DICOMweb endpoints, EHR / RIS / HIS portals.
💻 Developers & contributors
Build plug-ins, extend the architecture, contribute code, translations, or documentation.
Why Weasis
Built for clinical reading
Opens every common DICOM exam — CT, MR, ultrasound, X-ray, mammography, PET, ECG, structured reports, segmentations, RT plans. Multi-monitor, HiDPI, MPR, 3D, full annotation toolkit.Fits into your environment
Connects to your hospital's PACS or web archive, opens from any clinical portal in one click, and reads files from a local folder, USB drive, or DICOM CD. Works offline.Trusted, free, and open
Free under EPL 2.0 / Apache 2.0, open on GitHub — no vendor lock-in. Production-grade at HUG and across hospitals, trials, and portals worldwide — heir to a Geneva lineage of open imaging viewers.See the complete feature list → · Read the case studies →
Simple on the surface, advanced underneath
- 3D & MPR — volume rendering, oblique reconstruction, sync views, MIP slabs.
- Wide DICOM coverage — CT, MR, US, X-ray, PET, SR, ECG, audio, 4D, multi-frame.
- DICOM SEG & RT — overlays in 2D / MPR / 3D, RTSTRUCT, RTDOSE isodose, DVH.
- AI-friendly objects — secondary capture, parametric maps, GSPS, SR, segmentations.
- Measurements — calibrated distances, angles, ROI stats, histograms; saved as KO / PR.
- PACS & web integration — DICOMweb, DIMSE Q/R, portal launch via
weasis://. - Workflow ergonomics — multi-monitor, HiDPI, docking, shortcuts, themes, locales.
Community & support
- Questions — GitHub Discussions · dcm4che Forum · FAQs
- Bug reports & feature requests — GitHub Issues (see how to file a useful bug report)
- Get involved — contribute code, translations, documentation, stories
- Cite Weasis in a publication — citation format