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Clinical informatics, as an API

A suite of healthcare APIs, each built on FHIR and backed by clinical informatics expertise. All of them are documented for people and coding agents alike, with simple, open-source SDKs.

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

  • Scheduling API

    GET/v1/scheduling/slots
    • Tue, Jan 12, 9:00 AM

      General Practice · Dr. A. Okafor

      Riverside, Boston, MA

      Open
  • Medical Benefits API

    GET/v1/fhir/r4/InsurancePlan/H2406-013-000

    AARP Medicare Advantage from UHC FL-0021 (PPO)

    Medicare Advantage

    Specialist Visit, in network

    up to $65

    Copayment

  • MedList API

    POST/v1/fhir/r4/$reconcile-medications

    5 records sent

    2 entries back

    Janumet 50 mg-500 mg tablet

    active

    Why this status: Patient-reported use

    RxNorm 2709491 added by haau3

  • 8 APIs
  • 3 open-source SDKs
  • Agent-ready docs

What sets us apart

api.haau3.com

One API for all eight services

Workflow services

  • Scheduling APIGET /v1/scheduling/slots
  • MedList APIPOST /v1/fhir/r4/$reconcile-medications
  • Medical Benefits APIGET /v1/fhir/r4/InsurancePlan

Expertise, built in

Clinical informatics

Woven over the infrastructure and built into every workflow service, so your team does not have to build it.

Infrastructure, included

  • Provider Directory APIGET /v1/fhir/r4/Practitioner
  • Terminology API/v1/fhir/r4
  • Questionnaires APIGET /v1/fhir/r4/Questionnaire
  • Structured Sig APIPOST /v1/fhir/r4/$structure-dosage
  • SandboxPOST /v1/sandbox/fhir/r4/$process-message

Data sources

  • Records and directions you send
  • Published appointment schedules
  • CMS plan files
  • CMS's National Provider Directory
  • CMS's NPI Registry
  • LOINC and RxNorm
  • SNOMED CT, NCI Thesaurus and UCUM
  • Published health questionnaires

Every service. One API.

Each service answers a question in care. All of them live at one address and work with one account and the same SDKs, so you can start with one and add the rest.

Workflow services

Each answers a step in care: an open appointment, a medication list, what a plan covers.

  • Scheduling API

    Let people find open appointments across many providers, from one API that gathers each publisher's availability.

    GET/v1/scheduling/slots
    • Tue, Jan 12, 9:00 AM

      General Practice · Dr. A. Okafor

      Riverside, Boston, MA

      Open
    • FHIR R4
    • SMART Scheduling Links
    • FHIR Bulk Publish
    Learn more about the Scheduling API
  • MedList API

    Turn a patient's medication records, from however many sources, into one clean list with the evidence behind every entry.

    POST/v1/fhir/r4/$reconcile-medications

    5 records sent

    2 entries back

    Janumet 50 mg-500 mg tablet

    active

    Why this status: Patient-reported use

    RxNorm 2709491 added by haau3

    Built with the Terminology API: the RxNorm codes MedList adds come from the same RxNorm release the Terminology API serves.

    • FHIR R4
    • US Core
    • RxNorm
    Learn more about the MedList API
  • Medical Benefits API

    Show what a Medicare Advantage or ACA Marketplace plan covers and what a member pays, from the plan files CMS publishes.

    GET/v1/fhir/r4/InsurancePlan/H2406-013-000

    AARP Medicare Advantage from UHC FL-0021 (PPO)

    Medicare Advantage

    Specialist Visit, in network

    up to $65

    Copayment

    Built with the Provider Directory API: check whether the directory lists a provider in a Medicare Advantage plan's network.

    • FHIR R4
    • CARIN SBC profile (ballot)
    • CMS plan files
    Learn more about the Medical Benefits API

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, and synthetic data to test against.

  • Provider Directory API

    Resolve an NPI to the practitioner behind it, find practitioners and networks in CMS's National Provider Directory, and find pharmacies in CMS's NPI Registry.

    GET/v1/fhir/r4/Practitioner
    Practitioner
    Role
    Location
    • FHIR R4
    • CMS National Provider Directory
    Learn more about the Provider Directory API
  • Terminology API

    Look up a code, expand a value set or validate a code against LOINC and RxNorm, and get the standard FHIR answer back.

    GET/v1/fhir/r4/CodeSystem/$lookup

    RxNorm 861007

    metformin hydrochloride 500 MG Oral Tablet

    Term type: clinical drug (SCD)

    • FHIR R4
    • FHIR Terminology Service
    • LOINC
    • RxNorm
    Learn more about the Terminology API
  • Questionnaires API

    Serve standard health questionnaires as FHIR, exactly as their source publishes them, and build a standard response in your own app.

    GET/v1/fhir/r4/Questionnaire

    Built with the Terminology API: the same LOINC support finds and reads LOINC's forms.

    • FHIR R4
    • SDC
    • LOINC
    Learn more about the Questionnaires API
  • Structured Sig API

    Turn a prescription's free-text directions into a coded FHIR Dosage, with a review flag on anything a person should check.

    POST/v1/fhir/r4/$structure-dosage

    Take 1 tablet by mouth daily

    Method

    Take

    Dose

    1 tablet

    Route

    Oral route

    Timing

    once a day

    Built with the Terminology API: the medication's dose form is read from the same RxNorm release the Terminology API serves.

    • FHIR R4
    • SNOMED CT
    • NCI Thesaurus
    • UCUM
    • RxNorm
    Learn more about the Structured Sig API
  • Sandbox

    Build and test your pharmacy benefit check against a test insurer and test members whose answers never change, with no real patient involved.

    POST/v1/sandbox/fhir/r4/$process-message

    lisinopril 5 MG Oral Tablet

    Example Health Plan, test member EX0000001

    Covered

    Copay

    $10

    Total patient responsibility

    $10

    • FHIR R4
    • CARIN Real-Time Pharmacy Benefit Check
    Learn more about the Sandbox

SDKs for TypeScript, Python and Go

Install an SDK and make your first call. This one searches for open appointments, as the quickstart does.

Prefer plain HTTP? Every operation in the API reference has a cURL sample, and your own FHIR client works too.

TypeScriptnpm install @haau3/sdk
import { Haau3 } from "@haau3/sdk";

const haau3 = new Haau3(); // reads HAAU3_API_KEY
// Open appointment slots, here in Cambridge.
const { slots } = await haau3.searchSlots({ city: "Cambridge", state: "MA", limit: 1 });
console.log(slots[0]);
Pythonpip install haau3
import json

from haau3 import Haau3

client = Haau3()  # reads HAAU3_API_KEY
# Open appointment slots, here in Cambridge.
slots = client.search_slots(city="Cambridge", state="MA", limit=1)["slots"]
print(json.dumps(slots[0], indent=2))
Gogo get github.com/haau3/haau3-go
package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"

	"github.com/haau3/haau3-go"
)

func main() {
	ctx := context.Background()
	client, err := haau3.NewClient() // reads HAAU3_API_KEY
	if err != nil {
		log.Fatal(err)
	}
	// Open appointment slots, here in Cambridge.
	found, err := client.SearchSlots(ctx, haau3.SearchSlotsParams{City: new("Cambridge"), State: new("MA"), Limit: new(1)})
	if err != nil {
		log.Fatal(err)
	}
	slot, err := json.MarshalIndent(found.Slots[0], "", "  ")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(slot))
}

Point your coding agent at the docs

The docs are agent-ready, written for coding agents as well as people, so an agent learns the API from its source instead of guessing from training data that may predate it.

Build with AI coding agents
A first prompt
>Add the haau3 platform API to this project with its official SDK. Read https://docs.haau3.com/llms.txt first, then follow https://docs.haau3.com/quickstart.md to make a first call.
  • Docs as Markdown

    llms.txt, llms-full.txt, and every page at its own address with .md added.

  • The haau3 skill

    npx skills add https://docs.haau3.com

  • An MCP server

    https://docs.haau3.com/mcp searches and reads the docs. No key needed.

  • AGENTS.md for each SDK

    An index of every method, in under 8 KB, for your project's AGENTS.md.

Start building today

Create an organization, get a key and make your first call. More services are planned; see the roadmap.

Get started freeRead the docs
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Clinical informatics, as an API.

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  • Scheduling
  • MedList
  • Medical Benefits
  • Provider Directory
  • Terminology
  • Questionnaires
  • Structured Sig
  • Sandbox

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