Clinical Data APIs Overview

FHIRfly provides instant access to healthcare reference data through simple REST APIs.

Available APIs

API	Description	Data Source
NDC	National Drug Codes	FDA NDC Directory
NPI	Provider Identifiers	CMS NPPES
RxNorm	Drug Terminology	NLM RxNorm
RxClass	Drug Classifications	NLM MED-RT
UCUM	Units of Measure	Regenstrief UCUM
LOINC	Lab Codes	Regenstrief LOINC
ICD-10	Diagnosis Codes	CMS ICD-10
CVX	Vaccine Codes	CDC CVX
MVX	Manufacturer Codes	CDC MVX
FDA Labels	Drug Labels	FDA DailyMed
SNOMED CT	Clinical Concepts	SNOMED IPS Free Set
HCPCS Level II	Procedure & Supply Codes	CMS HCPCS
MS-DRG	Diagnosis Related Groups	CMS IPPS
Place of Service	Place of Service Codes	CMS POS
J-Code/NDC Crosswalk	J-Code to NDC Mapping	CMS ASP NDC-HCPCS

Common Patterns

All Clinical Data APIs follow consistent patterns:

Single Lookup

GET /v1/{api}/{code}

Batch Lookup

POST /v1/{api}/_batch
Content-Type: application/json
{"codes": ["code1", "code2", "code3"]}

Response Shapes

GET /v1/{api}/{code}?shape=compact|standard|full

See Response Shapes for details on each format.

Authentication

All Clinical Data API requests require authentication via API key or OAuth token.

Node.js

import { Fhirfly } from "@fhirfly-io/terminology";

// API Key
const client = new Fhirfly({ apiKey: "YOUR_API_KEY" });

// Or OAuth2
const client = new Fhirfly({
  clientId: "ffly_client_...",
  clientSecret: "ffly_secret_...",
});

const result = await client.ndc.lookup("0069-0151-01");

Response Format

All responses follow a consistent structure:

{
  "data": { /* resource data */ },
  "meta": {
    "source": { /* provenance (full shape only) */ },
    "legal": { /* licensing info */ }
  }
}

Error Responses

Status	Description
400	Invalid request (bad code format)
401	Missing or invalid authentication
403	Insufficient permissions (scope)
404	Code not found
429	Rate limit exceeded
500	Server error

{
  "error": "not_found",
  "error_description": "NDC code not found: 0000-0000-00"
}