Weasis is free and, judging by how it is built and distributed, a reasonable choice for a dental clinic: it is open-source software under the EPL 2.0 or Apache 2.0 licence, it has no price and no paid tier, and its installers are code-signed. What it is not is a certified medical device. The developers say so on their download page and in a dialog that appears on first launch. This page checks what “safe” and “free” actually cover for a practice. Facts were checked on 12 November 2026 against the project’s GitHub repository and documentation; the current release at that date is 4.8.0, published 31 October 2026. Status: Not tested yet — we have read the official sources, but we have not scanned the installers ourselves or run Weasis on a clinic workstation.
Weasis at a glance
| Question | Answer (checked 12 November 2026) |
|---|---|
| Price | Free. Open source, dual-licensed EPL 2.0 or Apache 2.0 (you choose) |
| Commercial use in a clinic | Allowed by the project’s FAQ, if you follow the licence terms |
| Current version | 4.8.0, published 31 October 2026 |
| Operating systems | Windows 10 or later (x86-64); macOS 12+ on Apple Silicon, macOS 11+ on Intel; Linux (DEB, RPM, Flatpak, Snap) |
| Needs Java or internet? | No Java to install (bundled); works fully offline once installed |
| Certified medical device? | No. The open-source build has no CE marking and is not FDA cleared |
| De-identifies DICOM files? | No. Exported or sent files keep their original patient attributes |
Our own catalogue page for Weasis may still list an earlier release; use the numbers above when you plan an install.
Is it free? What the licence lets you do
Weasis has one edition. There is no trial, no feature lock and no paid tier in the official download page or documentation. Since version 3.7.0 the source code is offered under EPL-2.0 OR Apache-2.0, and the repository’s licence file says exactly that. The project’s FAQ answers the commercial question directly: yes, you can use Weasis commercially, provided you comply with the licence. For a clinic that only installs and uses the viewer, that means no fee and no registration. If you modify Weasis source code and distribute the result, the EPL requires you to make those modifications available to others. Plug-ins you write can carry any licence.
That is different from RadiAnt DICOM Viewer, which is shareware (conditionally free): Windows-only, with a full-featured trial and a paid licence for continued use. If cost is the deciding factor, Weasis and Horos (free, macOS only) are the two free desktop options in our catalogue that include curved reconstruction for CBCT.
Is it safe? Three different questions
1. Is the software itself trustworthy?
The repository documents several measures: installers are code-signed, dependencies are tracked in a software bill of materials with continuous CVE monitoring, and every build is scanned by SonarCloud. These are the project’s own statements, and we have not audited them. What you can verify yourself in five minutes: download only from the official documentation site or from a package manager the project lists (the Microsoft Store, winget, Chocolatey, Homebrew, Flathub, Snap, AUR), and compare the file’s SHA-256 with the digest GitHub shows next to each release file. Avoid mirror sites and “download manager” wrappers.
2. What happens to patient data?
Weasis runs offline and opens files from a folder, USB drive, DICOM disc or ZIP archive without any network connection. It only talks to a network when you configure a PACS or DICOMweb source. That keeps the exposure small, but two points matter for privacy:
- Weasis can hide patient names on screen and in screenshots, prints and image exports. The FAQ is explicit that this is not de-identification: text burned into the image pixels is not removed, and DICOM files you export or send keep their original attributes. To share a study for teaching, use a tool built for de-identification and review every image.
- If you connect Weasis to a server such as Orthanc, the transport and login settings are what protect the data. The project lists HTTPS, Basic auth, OAuth 2.0 and OpenID Connect; set them up on the server side as well.
3. Is it safe for clinical decisions?
Weasis is a viewer. The first-launch dialog must be accepted before use, and the developers state that primary diagnostic use requires you to ensure compliance with the laws and rules of your jurisdiction. We make no regulatory claim for a dental practice: if you want a viewer with a regulatory status, ask the manufacturer of your X-ray or CBCT unit which viewer they supply and support.
Checklist for installing it in a clinic
- Pick one source: the Windows MSI or macOS PKG from the official page, or a package manager, so IT can update it centrally. Windows deployment also works with winget or Chocolatey.
- Check the OS: the Windows installer needs Windows 10 or higher, so Windows 7 machines are out.
- Update graphics drivers if you use 3D volume rendering; it needs a reasonably modern graphics card.
- Prefer the native installer over Flatpak or Snap if you read discs: both run sandboxed, and Snap has limited access to removable media.
- Record the version you installed. Releases appear several times a year, so read the changelog before updating a workstation. Version 4.8.0, for example, lists many changes to DICOMweb search, rendering and measurement tools, so test on one machine first.
- Decide who may export. Because exports keep patient attributes, treat any file leaving the clinic as identifiable.
Weasis compared with the other viewers we cover
| Viewer | Licence | Platforms | Key difference |
|---|---|---|---|
| Weasis | Free, open source (EPL 2.0 or Apache 2.0) | Windows, macOS, Linux | Curved MPR for CBCT, PACS and DICOMweb, runs offline |
| Horos | Free, open source | macOS only | Curved MPR and STL export on the Mac |
| RadiAnt | Shareware (conditionally free) | Windows | Fast; its EULA says it is not certified and must not be used for diagnostic decisions |
For a head-to-head on CBCT features, see Weasis vs Horos; the full list of free options is in our free dental imaging software guide.
Who should and should not use it
Good fit: a clinic that needs a free viewer on mixed Windows and Mac machines; IT staff who want a package-managed install; a practice that opens CBCT discs from referring dentists; teams running Orthanc as a small PACS.
Not a fit: practices that need implant planning, surgical guide design or tooth segmentation (Weasis shows DICOM segmentations but does not create them, and it cannot export STL models); anyone who needs a viewer with a regulatory clearance; anyone on Windows 7 or on a phone or tablet, since there is no Android or iOS version.
Limitations
- We have not run Weasis 4.8.0 ourselves; this page summarises official documentation and the project repository.
- “Free” covers the software, not the work around it: someone must install, update and support it. The project’s support is a community forum and GitHub issues.
- The ISO export with Weasis embedded (handy for sending a disc to a referring dentist) works on Windows x86-64 only, both to create it and to run it from the disc. On other platforms the export still writes a DICOM disc without the viewer.
- Our statements about code signing and scanning come from the project’s README and have not been independently verified.
- Not legal advice. Regulatory and privacy rules differ by country and state.
FAQ
Is Weasis free?
Yes. It is free and open source, with no paid edition, and it is dual-licensed under EPL 2.0 and Apache 2.0.
Is Weasis DICOM viewer safe?
The project signs its installers and publishes its code, and it runs offline. Download only from the official site or a listed package manager, and verify the checksum. It is a viewer, not a certified medical device, and it does not anonymise files you export.
Is Weasis open source?
Yes. The code is public on GitHub under EPL-2.0 OR Apache-2.0. Changes to Weasis code that you distribute must be shared under the EPL; separate plug-ins can use any licence.
Can a dental clinic use Weasis for business?
The project FAQ says commercial use is allowed if you follow the licence. Nothing in the documentation restricts clinics.
Is Weasis FDA cleared or CE marked?
No. The open-source distribution carries neither mark, and the developers require users to ensure compliance with local rules for any primary diagnostic use.
Does Weasis need the internet?
No. After installation it works fully offline. A network is needed only to reach a PACS or DICOMweb server you configure.
Last updated: 12 November 2026 · DentIIT editorial team. Licence, version and platform details are checked against each developer's official documentation; none of the tools listed here should be treated as a certified medical device unless its vendor says so.
