Orthanc-WSI brings support of whole-slide imaging for digital
pathology into Orthanc, the lightweight, RESTful Vendor Neutral
Archive for medical imaging.

It is made of 3 components:

(a) A command-line tool called "OrthancWSIDicomizer" that converts
    whole-slide images to DICOM. OpenSlide can be used to decode
    proprietary file formats.

(b) An Orthanc plugin to display such DICOM images in a standard Web
    browser thanks to OpenLayers.

(c) A command-line tool called "OrthancWSIDicomToTiff" that allows one
    to create a standard hierarchical TIFF file from some DICOM
    whole-slide image stored in Orthanc.

Homepage: https://orthanc.uclouvain.be/book/plugins/wsi.html