FAQs

Frequently Asked Questions

Table of Contents

What is Weasis?

Weasis is a standalone and web-based application designed for visualizing and analyzing images obtained from medical imaging equipment according to the DICOM standard. To learn more, visit the Weasis Medical Viewer page.

Which operating systems does Weasis run on?

Weasis runs on:

  • Windows — desktop installer or portable archive.
  • macOS — both Intel and Apple Silicon.
  • Linux — DEB, RPM, Flatpak, or Snap.

A web-launch option is also available — the Weasis Protocol opens the locally installed application from a portal click. See Download Weasis for the full installation matrix and platform notes.

Does the web launch require Weasis to be installed?

Yes. The web launch is not a browser-only viewer — it uses the weasis:// URI scheme to hand launch parameters to the locally installed Weasis application. Each user must install Weasis once from the Download page; every subsequent click on a weasis://... link (typically generated by a PACS portal, EHR, or weasis-pacs-connector / ViewerHub) then reuses that local install. The previous in-browser Java Web Start distribution was discontinued in version 3.5 for security, configuration, and compatibility reasons.

Does Weasis need an internet connection?

No — Weasis runs fully offline once installed. It opens DICOM files from any local source (file system, USB drive, DICOM CD / DVD, ZIP archive) without network access.

Is Weasis a certified medical device?

No. The open-source distribution of Weasis is not a certified medical device — it does not carry CE marking and is not FDA cleared. Any primary diagnostic use requires you (or your institution) to ensure full compliance with the laws and regulations applicable in your jurisdiction. The full disclaimer is displayed in a dialog the first time Weasis is launched and must be explicitly accepted before the application can be used; it is also reproduced on the Download Weasis page.

Healthcare organizations or vendors that need a certified product can build on the same code base and pursue certification themselves — the Eclipse Public License permits derivative commercial products.

Where can I ask questions about Weasis?

For general questions, use the Weasis forum or the GitHub discussions.

This website is organized by audience — start with the section that matches yours:

How do I report a bug?

Open an issue on the Weasis GitHub issue tracker. To help the maintainers reproduce the problem, please include:

  • The Weasis version and your operating system.
  • A short description of what you did and what happened, with a screenshot if relevant.
  • The log files — set the log level to DEBUG or TRACE, restart Weasis, reproduce the issue, and attach boot.log and the most recent default.log* files. See How to configure and view log files for the full procedure.

How do I contribute a translation?

Weasis translations are managed on a community translation platform. To improve an existing language or add a new one, follow the Translating Weasis guide. End-user instructions for picking the active language are in the Language & Regional Settings tutorial.

Can Weasis be used for commercial purposes?

Yes — Weasis is available for commercial use, provided you comply with the terms outlined in the license.

How to cite Weasis in a publication?

When citing Weasis in a publication, include the following details:

  • Author: Nicolas Roduit
  • Title: Weasis DICOM Viewer
  • Version: the Weasis version you used
  • URL: https://github.com/nroduit/Weasis
  • Access date: the date you accessed the URL

Citation example: Roduit, N. Weasis DICOM Viewer. Version 4.1.0. https://github.com/nroduit/Weasis (accessed 5 April 2023).

Why does Weasis use the Eclipse Public License?

The Eclipse Public License (EPL) is a commercially friendly open-source license approved by the Open Source Initiative (OSI). It offers several benefits:

  1. Business-friendly clauses — compared to LGPL, EPL includes more advantageous terms around patent retaliation and reverse engineering.
  2. Flexibility for derivative works — plugins and other extensions to Weasis can be distributed under any license (open source, freeware, or commercial). However, modifications to the existing source code of Weasis or its plugins must be made available to others if distributed.

Since version 3.7.0, the Weasis source code is distributed under a dual license: EPL-2.0 OR Apache-2.0. Users can choose the license that best fits their needs.

For more details, see the EPL 2.0 FAQ.

Can Weasis be included in DICOM CDs or other removable media?

Yes. Weasis can be embedded into a DICOM CD ISO so the recipient can launch it directly from the disc — currently supported on Windows x86-64 only. On other platforms, you can still produce a DICOM CD without the embedded viewer. See the CD/DVD Image section of the DICOM Export tutorial for the full procedure.

How do I enable Weasis logging?

To trace Weasis activities, enable the rolling log in the application preferences. See How to configure and view log files for the full configuration — including how to share the logs with the maintainers when filing a bug report.

Can I download DICOM files without a WADO server?

Yes — a WADO server is recommended, but not strictly required. Two alternative paths are supported:

  1. Build an XML manifest file — use the DirectDownloadFile and DirectDownloadThumbnail options described in the integration guide.

  2. Use the $dicom:get command — point at one or more files by URL:

    $dicom:get -r "http://external.server/images/MRIX_LUMBAR/img1.dcm http://external.server/images/img2.dcm"

    This works well for a small number of files. For larger studies or production deployments, prefer a proper WADO-RS / DICOMweb server — see DICOMweb Configuration.