FHIR API Development Services

Where FHIR integration consumes someone else's API, API development makes you the provider. Buyers usually fall into one of four groups:

• Health IT developers seeking ONC certification, who must meet the standardized API criterion at 45 CFR 170.315(g)(10), including US Core and SMART App Launch support.
• Payers subject to CMS rules: CMS-9115-F introduced Patient Access and Provider Directory APIs, and CMS-0057-F adds Provider Access, Payer-to-Payer and Prior Authorization APIs, with most API requirements taking effect from January 2027.
• Digital-health and SaaS platforms that want a partner-friendly API so health systems and other apps can integrate without bespoke interfaces.
• Provider organizations and networks exposing aggregated or registry data to affiliates and researchers.

• API design specification: supported resources and interactions, required and optional search parameters, operations (such as `$everything` or `$export`), paging and error conventions.
• Profile selection or authoring: adopting US Core, CARIN Blue Button, Da Vinci PDex or other IGs, or authoring your own profiles with FHIR Shorthand when no IG fits.
• Implementation: either a facade that translates FHIR requests into queries against your existing database, or a native FHIR store with data synchronized into it.
• Authorization server integration: SMART discovery at `.well-known/smart-configuration`, scopes, consent screens and token introspection.
• CapabilityStatement and developer documentation: a machine-readable statement at `/metadata` plus human documentation, sandbox and test data.
• Automated conformance suite: profile validation in CI and test runs with tools such as Inferno.

{
  "resourceType": "CapabilityStatement",
  "status": "active",
  "kind": "instance",
  "fhirVersion": "4.0.1",
  "format": ["json"],
  "rest": [{
    "mode": "server",
    "resource": [{
      "type": "Patient",
      "supportedProfile": ["http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient"],
      "interaction": [{ "code": "read" }, { "code": "search-type" }],
      "searchParam": [
        { "name": "_id", "type": "token" },
        { "name": "identifier", "type": "token" },
        { "name": "name", "type": "string" },
        { "name": "birthdate", "type": "date" }
      ]
    }]
  }]
}

The central architectural decision is whether FHIR is a translation layer over your existing system or a persisted copy. Our FHIR server architecture guide goes deeper; the short version:

1. Requirements and IG mapping: identify every regulatory or partner requirement and the IG version it references. Version pinning matters; a certification program and a payer rule may name different US Core versions.
2. Data profiling: inventory source data and find gaps against must-support elements before writing code.
3. API skeleton and auth: endpoints, SMART discovery, token validation and audit logging first, so security is not retrofitted.
4. Resource-by-resource build: implement mapping, search and validation for each resource, with tests per profile.
5. Conformance testing: run validators and test kits, fix failures, and record evidence for auditors or certification bodies.
6. Developer onboarding launch: publish documentation, open the sandbox, and define how third-party apps register.

Look for teams who talk in terms of profiles, must-support semantics and conformance evidence, not only endpoints. You can compare shortlisted firms in the FHIR API development companies directory.

• Have you taken an API through Inferno or a certification test run? What failed first time, and why?
• How do you decide between a facade and a persisted FHIR store for our data?
• How do you implement chained search, `_include` and `_revinclude`, and which will you not support?
• How will you keep our API aligned when US Core or a CMS-referenced IG publishes a new version?
• What does third-party app registration and access revocation look like in your design?
• How do you prevent over-disclosure, for example returning resources outside the scopes in a token?

Initial API builds are often fixed-scope for a defined resource set, followed by a retainer or support and maintenance agreement for version upgrades. Cost is driven by the number of resources and profiles, the complexity of mapping from your source schema, search breadth, whether Bulk Data export is required, and how much certification or audit evidence you need. Choosing a commercial FHIR server or a managed cloud FHIR service can shift effort from custom code to licensing, which changes the shape of the budget rather than simply reducing it.