The Osimis Web viewer is an evolution of the basic Orthanc Web viewer that adds tools for measuring, for viewing multiple series, and for split-pane.
This free and open-source by Osimis is a cross-platform, zero-footprint Web viewer for medical images. It proposes more advanced features than the basic Orthanc Web viewer, notably:
The code of the Osimis Web viewer plugin is licensed under the Affero General Public License (AGPL). Pay attention to the fact that this license is more restrictive than the license of the Orthanc core.