https://api.haau3.com and
backed by clinical informatics expertise. They are built on FHIR: every service but Scheduling
answers on one FHIR R4 base, and Scheduling implements SMART Scheduling Links, which is built on
FHIR. The Sandbox, at https://sandbox.haau3.com, is the API’s test environment: the
same paths, callable with no key, each operation answering its documented example. The docs are
agent-ready, written for coding agents as well as people, and open-source SDKs for TypeScript,
Python and Go call every endpoint.
The workflow services answer a step in care, and the building blocks below them are the standards
they stand on, each useful on its own. More services are planned. Every API open to customers today
is included in every plan. Free to start on the Developer plan.
The haau3 platform API is in preview: it may change as we build, usually to add features or improve performance.
Start building
Quickstart
Make a first call in the Sandbox with no account, then the same call in production with a key.
Authentication
How API keys work and the 401 contract.
Sandbox
The API’s test environment: production’s paths, no key needed, a fixed answer for every
documented example.
haau3 CLI
Check a project, call each API, and put a key in its env file without ever showing it.
SDKs
Open-source clients for TypeScript, Python and Go, with every endpoint as a typed call.
Build with AI coding agents
Give a coding agent the docs, the MCP server and an index of every SDK method.
API Reference
Interactive reference for every endpoint, generated from our contracts.
Workflow services
Each answers a step in care: an open appointment, a medication list, what a plan covers, what a prescription will cost.Scheduling
Find open appointments across providers: the Scheduling service aggregates SMART Scheduling
Links publishers.
MedList
Send one patient’s medication records and get back one reconciled medication list, with the
source records behind every entry.
Medical Benefits
Look up what a Medicare Advantage or ACA Marketplace plan covers and what a member pays.
Pharmacy Benefits
Not yet open to customers. Ask what a medication would cost, for a member’s coverage or
without patient details, as the CARIN pharmacy benefit check. Try it now in the Sandbox, where
a test insurer, Example Health Plan, answers for synthetic members.
Building blocks
The standards behind the services above, each useful on its own: who a provider is, what a code means, which form to ask, what a prescription’s directions say.Provider directory
Look up a practitioner by NPI or name, the roles by organization, location or specialty, and
networks and payers, from CMS’s National Provider Directory as it publishes it; and pharmacies
near a ZIP code, from CMS’s NPI Registry.
Terminology
Look up codes, expand value sets and validate codes against LOINC, RxNorm and ICD-10-CM, with the
standard FHIR answer.
Questionnaires
Fetch a standard questionnaire as FHIR, exactly as its source publishes it, and build the
response in your own app.
Structured Sig
Turn a prescription’s free-text directions into a FHIR Dosage, coded in SNOMED CT, NCIt and
UCUM, with the directions kept verbatim and a review flag on anything to check.