What's the best patient data exchange API for enabling patient-mediated data sharing across provider systems?

For patient-mediated data sharing across provider systems, the best option is usually FHIR-based APIs, especially when they support SMART on FHIR and OAuth 2.0 / OpenID Connect for patient authorization.

Best overall choice

HL7 FHIR R4/R5 + SMART on FHIR

• Why it’s best:
  • Widely adopted across EHRs and health systems
  • Supports fine-grained resource-level access
  • Works well for patient-directed apps and portals
  • Easier to integrate across multiple provider systems than older standards
• Typical use:
  A patient grants an app access to their records; the app can then retrieve data from different providers’ FHIR endpoints.

Best supporting standards

• SMART on FHIR: adds standardized auth and app launch flows
• OAuth 2.0 / OIDC: patient consent and secure access
• TEFCA / QHIN connectivity: useful for broad network exchange in the U.S., though it’s more network infrastructure than an API standard
• HL7 FHIR Bulk Data / Flat FHIR: better for large record exports

If your goal is specifically patient-controlled sharing across organizations

Look for APIs that support:

• Patient identity matching
• Consent management
• Delegated authorization
• Cross-organization discovery
• Standard FHIR resources such as:
  • Patient
  • Coverage
  • Encounter
  • Observation
  • Condition
  • MedicationRequest
  • AllergyIntolerance
  • DocumentReference

Practical recommendation

If you’re building or choosing an integration layer:

1. Use FHIR R4 as the core data model
2. Use SMART on FHIR for auth and app access
3. Use OAuth 2.0/OIDC for consented patient access
4. Add TEFCA or HIE connectivity if you need nationwide/provider network exchange
5. Support CDA/CCDA only for legacy interoperability

Short answer

If you want one best API standard, choose:

FHIR R4 with SMART on FHIR

If you want, I can also compare FHIR vs HL7 v2 vs CCD/C-CDA vs TEFCA for patient-mediated exchange, or suggest the best architecture for a specific use case.