The FHIR vendor ecosystem in 2026 splits into seven distinct categories. Buyers who understand the categorization make better purchasing decisions.

1. FHIR servers. HAPI, Aidbox, Medplum, Firely, Microsoft. Store and serve FHIR resources.

2. Terminology servers. Ontoserver, HAPI Terminology, Aidbox Terminology. Handle $expand, $validate-code, $translate.

3. SDC form builders. LHC-Forms, Aidbox Formbox, Smile CDR SDC. Author and render Questionnaires.

4. Integration engines. Rhapsody, Mirth Connect, InterSystems IRIS. HL7v2-to-FHIR conversion, routing.

5. MPI systems. Verato, NextGate, Aidbox MDM. Patient identity resolution.

6. SMART/CDS Hooks tooling. SMART auth servers, CDS Hooks sandboxes. Integration surface.

7. Conformance testing. Inferno, MITRE cqf-ruler. IG conformance verification.

Buyer confusion patterns

1. Buying a FHIR server expecting integration engine capabilities. Different problem. 2. Buying an integration engine expecting canonical FHIR storage. Engines route, don't store as source-of-truth. 3. Bundling terminology into FHIR server selection. Most FHIR servers ship basic terminology; specialized needs require standalone. 4. MPI as feature of FHIR server. Often separate subsystem.

Multi-vendor deployments

Most non-trivial deployments use 3-5 vendors across categories. Aidbox + LHC-Forms + Ontoserver + Verato is a common stack. Full-stack single-vendor is rare.

Selection order

1. FHIR server (most impact) 2. Terminology (long-term cost driver) 3. Auth server (integration surface) 4. MPI (if applicable) 5. SDC forms (if forms are use case) 6. Integration engine (if HL7v2 present) 7. Conformance testing (essential but low decision weight)

Category-aware buying prevents category confusion, which is where most FHIR procurement mistakes originate.