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.
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- Open
Tue, Jan 12, 9:00 AM
General Practice · Dr. A. Okafor
Riverside, Boston, MA
Medical Benefits API
GET/v1/fhir/r4/InsurancePlan/H2406-013-000AARP Medicare Advantage from UHC FL-0021 (PPO)
Medicare Advantage
Specialist Visit, in network
up to $65
Copayment
MedList API
POST/v1/fhir/r4/$reconcile-medications5 records sent
2 entries back
Janumet 50 mg-500 mg tablet
activeWhy 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/$process-message
Data sources
- Records and directions you send
- Published appointment schedules
- CMS plan files
- CMS's National Provider Directory
- CMS's NPI Registry
- LOINC and RxNorm
- SNOMED CT, NCI Thesaurus and UCUM
- Published health questionnaires
Every service. One API.
Each service answers a question in care. All of them live at one address and work with one account and the same SDKs, so you can start with one and add the rest.
Workflow services
Each answers a step in care: an open appointment, a medication list, what a plan covers.
Scheduling API
Let people find open appointments across many providers, from one API that gathers each publisher's availability.
GET/v1/scheduling/slots- Open
Tue, Jan 12, 9:00 AM
General Practice · Dr. A. Okafor
Riverside, Boston, MA
- FHIR R4
- SMART Scheduling Links
- FHIR Bulk Publish
MedList API
Turn a patient's medication records, from however many sources, into one clean list with the evidence behind every entry.
POST/v1/fhir/r4/$reconcile-medications5 records sent
2 entries back
Janumet 50 mg-500 mg tablet
activeWhy 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
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/H2406-013-000AARP Medicare Advantage from UHC FL-0021 (PPO)
Medicare Advantage
Specialist Visit, in network
up to $65
Copayment
Built with the Provider Directory API: check whether the directory lists a provider in a Medicare Advantage plan's network.
- FHIR R4
- CARIN SBC profile (ballot)
- CMS plan files
Building blocks
The standards behind the services above, each useful on its own: who a provider is, what a code means, which form to ask, what a prescription's directions say, and synthetic data to test against.
Provider Directory API
Resolve an NPI to the practitioner behind it, find practitioners and networks in CMS's National Provider Directory, and find pharmacies in CMS's NPI Registry.
GET/v1/fhir/r4/Practitioner- FHIR R4
- CMS National Provider Directory
Terminology API
Look up a code, expand a value set or validate a code against LOINC and RxNorm, and get the standard FHIR answer back.
GET/v1/fhir/r4/CodeSystem/$lookupRxNorm 861007
metformin hydrochloride 500 MG Oral Tablet
Term type: clinical drug (SCD)
- FHIR R4
- FHIR Terminology Service
- LOINC
- RxNorm
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/QuestionnaireBuilt with the Terminology API: the same LOINC support finds and reads LOINC's forms.
- FHIR R4
- SDC
- LOINC
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/$structure-dosageTake 1 tablet by mouth daily
Method
Take
Dose
1 tablet
Route
Oral route
Timing
once a day
Built with the Terminology API: the medication's dose form is read from the same RxNorm release the Terminology API serves.
- FHIR R4
- SNOMED CT
- NCI Thesaurus
- UCUM
- RxNorm
Sandbox
Build and test your pharmacy benefit check against a test insurer and test members whose answers never change, with no real patient involved.
POST/v1/sandbox/fhir/r4/$process-messagelisinopril 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
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.
npm install @haau3/sdkimport { 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]);pip install haau3import 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))go get github.com/haau3/haau3-gopackage 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 agentsAdd 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.