FHIR (Fast Healthcare Interoperability Resources, pronounced “fire”) is the modern standard for healthcare data exchange, maintained by HL7. FHIR defines API resources (Patient, Observation, MedicationRequest, etc.) and how to interact with them via REST. US federal regulation has required EHRs to support FHIR APIs since 2022.
For patient portals, FHIR is what enables third-party patient communication platforms (Klara, Phreesia, Mend) to layer on top of EHRs, and it’s the foundation for custom patient experiences built on top of Epic, Oracle Health, athenahealth, and other major EHRs.
See HIPAA-Compliant Patient Portals and Patient Portal Software.