---
name: haau3
description: Use when calling the haau3 platform API (api.haau3.com) from code. It serves open appointment slots from SMART Scheduling Links publishers; Medicare Advantage and ACA Marketplace plans and their provider networks; one reconciled medication list from a patient's FHIR records; LOINC and RxNorm terminology; the CMS National Provider Directory; and FHIR Questionnaires. Covers the API key, the SDKs for TypeScript, Python and Go, and where every endpoint is documented.
---

# haau3 platform API

The haau3 platform API is in preview: it may change as we build, usually to add features or improve performance.

## Services

- **Scheduling**, at `https://api.haau3.com/v1/scheduling`: open appointment slots and provider locations from many SMART Scheduling Links publishers, in one search.
- On the FHIR R4 base, `https://api.haau3.com/v1/fhir/r4`:
  - **Plan Benefits**: Medicare Advantage and ACA Marketplace plans as `InsurancePlan`, searchable by state or county, and which providers are in a plan's network (`$in-network`).
  - **MedList**: one reconciled medication list from one patient's FHIR medication records (`$reconcile-medications`). It receives patient data, so read its page before sending any.
  - **Terminology**: LOINC and RxNorm lookups, code validation and value set expansion.
  - **Provider directory**: practitioners and their roles, organizations, payers and networks, network membership, services, locations and endpoints, from the CMS National Provider Directory.
  - **Questionnaires**: FHIR Questionnaires such as the PHQ-9, by id or by canonical URL.
  - A batch `Bundle`, `POST /v1/fhir/r4`, carries several of these requests in one.

## The API key

- Every endpoint needs an API key, created on https://platform.haau3.com and sent as `Authorization: Bearer <key>`. No other header carries it.
- The key is a secret: call the API from a server, never from a browser.
- Every error under `/v1/fhir` is a FHIR `OperationOutcome`, and every other error an RFC 9457 problem. https://docs.haau3.com/errors.md lists each status, whether to retry it, and each plan's limits.

## SDKs

- TypeScript `npm install @haau3/sdk`, Python `pip install haau3`, Go `go get github.com/haau3/haau3-go`. Each reads the key from `HAAU3_API_KEY` and names each method by the endpoint's operationId: https://docs.haau3.com/sdks.md
- An index of every SDK method, to paste into a project's `AGENTS.md`: https://docs.haau3.com/ai-coding-agents.md

## Where to read more

- https://docs.haau3.com/llms.txt lists every docs page as Markdown, and https://docs.haau3.com/quickstart.md makes a first call.
- https://api.haau3.com/openapi.json is the API's OpenAPI 3.1 document.