FHIR (Fast Healthcare Interoperability Resources)
FHIR is HL7’s modern healthcare interoperability standard: clinical data is modeled as resources (Patient, Observation, Encounter, MedicationRequest…) exchanged as JSON or XML over REST APIs — the format behind national patient-access APIs and SMART health apps.
Resources and REST
FHIR models healthcare as composable resources with predictable URLs — /Patient/123, /Observation?patient=123&code=8480-6. Resources serialize as JSON or XML, conform to profiles that constrain fields for specific use cases (US Core, EU Laboratory Report, national base profiles), and are validated against the FHIR specification’s schemas.
FHIR R4 is the first normative release and the version most deployments and regulations target (US ONC rules require it for patient-access APIs); R4B and R5 refine the model. Bundles wrap resource collections for documents and messages, and SMART on FHIR defines the OAuth-based app-launch framework.
Working with FHIR
For developers the practical surface is JSON resources: required fields (like a resource’s resourceType), coded elements with system+code pairs, and reference links between resources. Our viewer validates structure and flattens field paths for inspection — useful when debugging why a payer or national API rejected a resource.
Frequently Asked Questions
Which FHIR version should I use?
R4 is the safe default — it is the first normative release, the version US ONC rules require for patient-access APIs, and what most profiles and national implementations target. R4B/R5 refine the model but adoption is still catching up.
Related Standards
- •HL7 FHIR R4 / R4B / R5
- •US Core / national base profiles; SMART on FHIR
Free Tools & Resources
Further Reading
Need help with this?
We consult and build across all of these domains — tell us what you are working on.