Should you build or buy Healthcare Integration Engine (HL7/FHIR)?
A healthcare integration engine, or interface engine, routes and translates clinical messages between electronic health records, lab systems, and other applications using standards like HL7 and FHIR. Hospitals and health information exchanges run it to keep patient data flowing correctly between systems that were never built to talk to each other directly.
You can run this yourself, and most organizations that do so are on the open Mirth lineage or a FHIR-native platform. The honest question is whether you want to own 24x7 operations, patching and high availability for the interfaces that feed your clinical systems; if not, buy support for the open engine rather than a proprietary one.
Build it, buy it, or bridge?
When building makes sense
Interface engines are one of the clearest build cases in healthcare IT, and the record backs that up at real scale. A regional health information exchange built on Mirth Connect connects more than 50 hospitals, handling roughly 10,000 ADT messages a day with peaks around 50 per second, production-grade throughput on an open engine. FHIR-native stacks built on HAPI FHIR run similarly serious workloads: OpenELIS deploys a HAPI FHIR server for lab orders and results in production across national laboratory networks in Cote d'Ivoire and Tanzania. What changed the calculation in 2025 is that Mirth Connect 4.6 moved to a closed-source, proprietary license, with version 4.5.2 the last fully open-source release, so a team building on Mirth today must plan around that license boundary. Interface work itself is only moderately specific and confers no edge over another hospital doing the same routing, so the build case rests entirely on whether the team wants to own 24x7 operations and patching.
When buying makes sense
The buy case here is really a support case, not a functionality case, and that distinction matters for how you shop. Commercial engines like Rhapsody, Redox, and InterSystems HealthShare run interfaces on largely the same HL7 and FHIR standards that open engines handle, and Forrester's own commissioned study found a 193% three-year ROI and $1.59 million net present value for Rhapsody's composite customer, on $2.42 million in benefits. What that price buys is a vendor on call during an outage, structured onboarding, and monitoring, not a fundamentally different routing capability. Mirth Connect's move to a closed-source license for version 4.6 also means the open-and-free-forever assumption behind some build decisions no longer holds without qualification. Buy support for the open engine you are already comfortable running rather than a fully proprietary one, unless the organization genuinely does not want to own 24x7 operations and patching for interfaces feeding its clinical systems.
The desk read
Build-versus-buy analysis for Healthcare Integration Engine (HL7/FHIR) is being written. In the meantime, the framework that drives every B4 call is on the B4 Index page.
Frequently asked
Are open-source interface engines actually used at hospital scale, or just for small deployments?
At real scale. A regional health information exchange running Mirth Connect connects more than 50 hospitals and processes about 10,000 ADT messages a day, with traffic peaking around 50 messages per second. FHIR-native engines built on HAPI FHIR run comparable production workloads elsewhere.
What changed with Mirth Connect's licensing in 2025?
Version 4.6 moved to a closed-source, proprietary license on March 19, 2025, with 4.5.2 remaining the last release under the open-source Mozilla Public License. Existing open-source versions stay available under their original terms, but new releases going forward carry the proprietary license.
What does a commercial interface engine actually add over an open one?
Mostly support, monitoring, and a vendor to call during an outage, not different routing or translation capability. Forrester's commissioned study found Rhapsody delivers a 193% three-year ROI and $1.59 million net present value, built on avoided integration-engineering hires and faster deployment rather than functionality an open engine lacks.
What are the main healthcare integration engine vendors?
Representative vendors include InterSystems HealthShare, Redox (device/data integration), Rhapsody Integration Engine, Redox. The real choice is usually between paying for support on an open engine or a fully proprietary one. B4 Pro includes the category score and the full vendor list.