Top healthcare interoperability APIs based on HL7 and FHIR include Epic FHIR APIs, Oracle Cerner Ignite, Google Cloud Healthcare API, Microsoft Azure Health Data Services, InterSystems HealthShare, Redox, Mirth Connect, Smile Digital Health, Particle Health, and CommonWell/Carequality. These differ in how well they support FHIR R4/US Core and legacy HL7 v2 data exchange across EHR systems. Cloud platforms like Google and Azure offer the best scalability and real-time data sharing, while Epic and Cerner provide strong native EHR integration but limited cross-system flexibility. Redox and Mirth Connect are widely used for bridging HL7 and FHIR between hospitals, and InterSystems and Smile focus on enterprise-wide data unification. All support HIPAA/GDPR security, but choice depends on whether the need is cloud scalability, hospital integration, or cross-network interoperability.
