Technology
The stack, explained.
The components in this platform were not assembled opportunistically. Each was chosen because it has a track record in production clinical environments, a real maintenance community, and a public codebase that can be audited, forked, or handed to a successor without negotiation. Nothing here is a black box.
Core components
dcm4chee-arc
The core of the system is dcm4chee-arc — the most widely deployed open source DICOM archive in clinical use. It handles study ingestion, storage, retrieval, and the DICOMweb APIs that modern viewers depend on. It has been in active development for over two decades and is used in hospitals across Europe and beyond. It is not a hobbyist project.
Keycloak
Identity and access management is handled by Keycloak, an enterprise-grade open source platform used at scale across healthcare and government infrastructure. In a clinical environment where multiple roles — radiologists, clinicians, students, administrators — need different levels of access to the same system, proper role-based access control is not optional. Keycloak provides it without requiring a proprietary identity vendor.
PostgreSQL
Both dcm4chee-arc and Keycloak use PostgreSQL as their database layer — the most capable open source relational database in production use, with a reliability record spanning decades.
Docker and Docker Compose
Every component in the stack runs in its own Docker container, orchestrated by Docker Compose. This is not incidental. Containerisation means each service is isolated, version-pinned, and independently restartable — a failed viewer process cannot affect the archive, a Keycloak update can be tested without touching the database, and the entire stack can be reproduced exactly on a new server from a handful of configuration files. It is the operational discipline that makes a multi-component open source system maintainable by someone other than the person who built it.
Traefik
Traefik acts as the reverse proxy — routing incoming requests to the correct service, terminating TLS, and managing Let's Encrypt certificates automatically. It is the only component with a public-facing port; everything else is internal.
OVHcloud
The infrastructure runs on OVHcloud dedicated servers — French-owned, EU-jurisdiction, with no US parent and no exposure to the CLOUD Act. Data sovereignty is not a feature flag here; it is a consequence of the infrastructure choice. For a fuller explanation of why this matters, see the About page.
Wiki.js
Every deployment includes a Wiki.js knowledge base — a structured, role-aware documentation system running alongside the PACS stack. It provides a living record of configuration decisions, modality onboarding notes, issue resolutions, and operational guidance. Public access is available by default; deeper access levels are implemented and configured during system setup to suit the practice's own needs.
The viewers
Three viewers are available, each suited to a different context and level of technical engagement.
dcm4chee-arc UI
The built-in web interface of the archive itself — a full-featured PACS front-end accessible in any browser, with no installation required. Study management, worklist, image display, and user administration are all available here. It is the day-to-day interface for most users.
OHIF Viewer
The OHIF Viewer is a dedicated, zero-install, browser-native DICOM viewer built on the DICOMweb standard. It provides a clean, focused viewing experience — window/level adjustment, multi-series display, measurement tools — without requiring anything beyond a modern browser. It is the right choice for remote reporting, student access, or any context where installation is not practical.
Weasis
Weasis is the production viewer of choice for demanding clinical work. Unlike the browser-based options above, Weasis is a native application — installed once on a workstation, it connects directly to the PACS via DICOMweb and provides capabilities that browser rendering cannot match: true multi-monitor support, full DICOM conformance including display of all standard modalities, precise window/level control, and performance characteristics suited to high-volume reading sessions. It requires installation, which is why it is not the zero-friction demo option — but for a radiologist doing serious work, it is the right tool.
No licensing fees. Ever.
Proprietary PACS systems typically charge per scan, per seat, or per year — a recurring cost that scales with clinical activity regardless of whether the underlying software has changed. Every component here is open source. There are no licensing fees to run the system, no per-scan charges, and no annual software costs. What you pay for is the work of deploying it correctly and, if you choose, the assurance of having someone maintain it.