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OpenIntegrationEngine/engine
An open source fork of the now closed-source Mirth Connect. Installers for the engine are in this repository.
Open Integration Engine is a community fork of Mirth Connect, the HL7 and FHIR interface engine that moved to a proprietary licence. This repo holds the Java server, the desktop client and the installers, and it is aimed at health IT teams and integration engineers who need a message router and transformer without a vendor licence attached.
The build is easy to start with: a committed Gradle wrapper and a .sdkmanrc pinning the JDK mean ./gradlew build works without a pile of setup notes. The ci/ directory runs the suite against Postgres, MySQL, Oracle, SQL Server and Derby on both Alpine and Ubuntu images, which is a real persistence matrix rather than one embedded database. The XXE channels under ci/tests for the XSLT step and the XML batch reader are regression tests for the XML parser attack surface, which is better than a comment saying the parser is locked down. MPL 2.0 is file-level copyleft, so changes to engine files stay open while channels and scripts built on top of it do not have to be published.
The README is mostly positioning, and the roadmap is six short bullets such as 'Stabilize codebase' and 'Enhance UX/UI' with no milestones or owners. The README says nothing about migrating an existing Mirth Connect install, which is the first question anyone adopting this will ask. Binary jars are committed under client/lib (HAPI, jai_imageio, openjfx), so dependency upgrades show up as diffs of opaque archives and you have to check provenance and licence for each one yourself. The README says JDK 17 is the only prerequisite, but the CI images are built on Temurin 21, so either the docs are stale or CI tests a different runtime from the one people are told to use. Before putting a hospital's interfaces on this, check how many people can merge to main, since the governance lives in a separate repo and the maintainer pool is not visible from here.