Google Health API Integration

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Overview

Google Health data reaches Open Wearables through two independent paths that share the single google provider identity:

Health Connect (mobile SDK) — data pushed from an Android device via the Sync SDK. See the Android SDK guide.
Google Health API (cloud OAuth) — this guide. A server-side OAuth 2.0 flow against the Google Health API that lets you connect a user’s Google account and pull their data over REST, plus receive notify-only webhooks.

The Google Health API is an aggregation layer: it surfaces data from every source connected to the user’s Google Health account — the phone’s Health Connect store, Fitbit, Google Fit, and other apps — not just one device.

Supported data types

Data type	Path
Steps, distance, calories, hydration	24/7 metrics
Heart rate, resting heart rate, HRV (RMSSD + SDNN)	24/7 metrics
VO₂ max, respiratory rate, SpO₂	24/7 metrics
Weight, body fat, core body temperature, blood glucose	24/7 metrics
Workouts (Exercise sessions)	Sessions
Sleep (with stages)	Sessions

Data delivery

Method	Description
Polling (pull)	Open Wearables periodically fetches data via the Health API (Celery Beat), driven by the fetch mode below.
Webhooks (notify-only)	Google sends a lightweight ping naming the changed `dataType` and time intervals; Open Wearables then fetches the changed data over REST. Requires a project-level subscriber registration.

Data granularity and fetch modes

The Health API exposes the same underlying data through three different operations. Open Wearables picks one per the DEFAULT_DATA_GRANULARITY setting, and — at the finest granularity — the GOOGLE_USE_RECONCILE flag.

Granularity	Operation	Resolution	Cross-source	Device attribution
`raw` + `GOOGLE_USE_RECONCILE=true` (default)	`dataPoints:reconcile`	native	merged & deduplicated	none
`raw` + `GOOGLE_USE_RECONCILE=false`	`dataPoints` (list)	native	raw, per-source	per-device
`hourly` / `daily`	`dataPoints:rollUp`	windowed	reconciled	none

GOOGLE_USE_RECONCILE only takes effect at raw granularity. hourly/daily always use windowed rollUp aggregates regardless of the flag.

Reconcile vs. list — why it matters

A user commonly has the same activity reported by multiple sources (e.g. the phone’s pedometer and the Fitbit app both counting steps). The two modes handle that overlap differently:

reconcile (default) returns one merged stream, deduplicated across all sources at the interval level — exactly what the native Google Health / Fitbit app displays. There is no single device behind a merged value, so reconciled points carry no device attribution (device_model is empty).
list returns the raw per-source points, each tagged with its originating device. This preserves device attribution but stores overlapping sources separately; Open Wearables then deduplicates on read by source priority (it does not sum them).

A concrete example — steps for one day for a user tracked by both their phone (Health Connect) and Fitbit MobileTrack:

	steps
Fitbit MobileTrack (list, one source)	2506
Phone / Health Connect (list, one source)	1919
`reconcile` (merged)	2560
What the native health app shows	2560

Reconcile (2560) matches the app exactly — it keeps intervals that either source captured while removing the overlap. Read-time dedup of the list data would instead pick a single source (1919), which is why reconcile is the default: it produces app-accurate totals.

Choose list (GOOGLE_USE_RECONCILE=false) only when you specifically need per-device attribution (e.g. to know which watch recorded a reading). For app-matching totals, keep the default.

What you need by the end

A Google Cloud project with the Health API enabled
OAuth client credentials (Client ID + Secret) with the Google Health scopes
Redirect URI registered in your OAuth client
(Webhooks only) A service account for project-level subscriber registration

Prerequisites

A Google Cloud project
Access to the Google Health API for that project (gcloud services enable health.googleapis.com)

Application walkthrough

Enable the Health API and create an OAuth client

In the Google Cloud Console, select your project and enable the Health API:

gcloud config set project YOUR_PROJECT_ID
gcloud services enable health.googleapis.com

Then create an OAuth 2.0 Client ID (Web application) under APIs & Services → Credentials, and add your server-side callback as an Authorized redirect URI:

Local dev: http://localhost:8000/api/v1/oauth/google/callback

Store the Client Secret securely — Google shows it once.

Configure credentials in Open Wearables

Add the following to your .env file:

#--- Google ---#
GOOGLE_CLIENT_ID=your-google-client-id
GOOGLE_CLIENT_SECRET=your-google-client-secret
GOOGLE_DEFAULT_SCOPE=openid email https://www.googleapis.com/auth/googlehealth.activity_and_fitness.readonly https://www.googleapis.com/auth/googlehealth.health_metrics_and_measurements.readonly https://www.googleapis.com/auth/googlehealth.nutrition.readonly https://www.googleapis.com/auth/googlehealth.sleep.readonly https://www.googleapis.com/auth/googlehealth.settings.readonly
# Fetch mode for raw-granularity 24/7 data (see "Data granularity and fetch modes")
GOOGLE_USE_RECONCILE=true

Configuration details:

Variable	Description	Default
`GOOGLE_CLIENT_ID`	OAuth Client ID	—
`GOOGLE_CLIENT_SECRET`	OAuth Client Secret	—
`GOOGLE_DEFAULT_SCOPE`	Space-separated Health API scopes to request	(full read-only set)
`GOOGLE_USE_RECONCILE`	`true` = reconcile (merged, app-accurate, no device attribution); `false` = list (per-device). Only applies at `raw` granularity.	`true`
`DEFAULT_DATA_GRANULARITY`	`raw` \| `hourly` \| `daily` — see the fetch modes table	`raw`

The redirect URI is derived from API_BASE_URL — it must match the Authorized redirect URI on your OAuth client ({API_BASE_URL}/api/v1/oauth/google/callback).

Connect a user via OAuth

With credentials configured and your instance running, initiate the OAuth flow.

Using the Open Wearables frontend? You don’t need any of the curls below — open the connect view and click Connect on Google Health. The frontend runs this whole authorize → consent → callback → verify flow for you. The steps below are for integrating directly against the API.

1. Get the authorization URL:

curl -X GET "http://localhost:8000/api/v1/oauth/google/authorize?user_id={user_id}&redirect_uri=http://localhost:3000/users/{user_id}" \
  -H "X-Open-Wearables-API-Key: YOUR_API_KEY"

2. Redirect the user to the returned authorization_url. They log in to Google and grant consent.3. Google redirects back to {API_BASE_URL}/api/v1/oauth/google/callback; Open Wearables exchanges the code for tokens and stores the connection. It also resolves the user’s stable healthUserId (via the Health API identity endpoint) as the connection’s provider user id — this is what inbound webhooks are matched against.4. Verify the connection:

curl -X GET "http://localhost:8000/api/v1/users/{user_id}/connections" \
  -H "X-Open-Wearables-API-Key: YOUR_API_KEY"

You should see a connection with "provider": "google" and "status": "active".

Sync data

An initial sync runs automatically after a successful OAuth connection. To trigger one manually:

curl -X POST "http://localhost:8000/api/v1/providers/google/users/{user_id}/sync" \
  -H "X-Open-Wearables-API-Key: YOUR_API_KEY"

Verify the integration

Fetch a synced 24/7 series (e.g. steps):

curl -X GET "http://localhost:8000/api/v1/users/{user_id}/timeseries/steps?start_date=2026-01-01T00:00:00Z&end_date=2026-02-01T00:00:00Z" \
  -H "X-Open-Wearables-API-Key: YOUR_API_KEY"

If data is returned, your Google Health API integration is working end-to-end.

Webhooks

Google Health webhooks are notify-only: each notification names the changed dataType, operation (UPSERT/DELETE), and the physical-time intervals that changed — but carries no data. Open Wearables verifies the request, then fetches the changed data over REST for those intervals. Two distinct secrets are involved:

GOOGLE_WEBHOOK_SECRET — a bearer token you register with Google that it echoes back in the Authorization header of every notification, so Open Wearables can verify the ping is genuine. Defaults to SECRET_KEY if unset.
Service-account credentials — used only to register the subscriber (a project-level admin call). Not involved in receiving notifications.

Receiving and processing webhooks needs only GOOGLE_WEBHOOK_SECRET. The service account is required only to register the subscriber programmatically — you can also register it manually via gcloud/the API console.

Webhook subscriber registration

Subscribers live at the project level (POST /v4/projects/{project}/subscribers), so registration authenticates as the project via a service account, not a user’s OAuth token.

gcloud commands need the project ID (e.g. open-wearables-prod). The GOOGLE_PROJECT_ID env var, however, needs the project number (e.g. 123456789012) — the subscriber API requires the number in its path.

Create a service account

gcloud iam service-accounts create health-webhooks \
  --project=YOUR_PROJECT_ID \
  --display-name="Health API webhook subscriber registration"

# Grant a role that can manage Health API subscribers (narrow this to the
# dedicated Health API role once confirmed; roles/editor works but is broad):
gcloud projects add-iam-policy-binding YOUR_PROJECT_ID \
  --member="serviceAccount:health-webhooks@YOUR_PROJECT_ID.iam.gserviceaccount.com" \
  --role="roles/editor"

Provide the credentials

Either mount a JSON key and point to it, or rely on Application Default Credentials (ADC) if running on GCP:

gcloud iam service-accounts keys create ./config/health-webhooks-key.json \
  --project=YOUR_PROJECT_ID \
  --iam-account=health-webhooks@YOUR_PROJECT_ID.iam.gserviceaccount.com

Add to .env:

GOOGLE_PROJECT_ID=your-project-number   # the numeric project NUMBER, not the ID
GOOGLE_SERVICE_ACCOUNT_FILE=config/health-webhooks-key.json   # unset = use ADC
# GOOGLE_WEBHOOK_SECRET=your-token   # optional; defaults to SECRET_KEY

Subscriber registration runs in the Celery worker, not the backend/API service. The key file (or credentials) and the GOOGLE_* env vars must be present on the worker service — a key mounted only into the backend container won’t be seen.

A JSON key never expires until deleted — prefer ADC / Workload Identity in production, and keep key files out of version control.

Switching the provider’s live sync mode to webhook registers the subscriber automatically. Google then performs an endpoint-verification handshake (POST {"type":"verification"}) against {API_BASE_URL}/api/v1/providers/google/webhooks, which must return 2xx when authenticated. Once verified, notifications begin flowing.

Variable	Description	Default
`GOOGLE_PROJECT_ID`	GCP project number (not ID) that owns the subscriber. Get it with `gcloud projects describe YOUR_PROJECT_ID --format='value(projectNumber)'`.	—
`GOOGLE_SERVICE_ACCOUNT_FILE`	Path to the SA JSON key; unset uses ADC	—
`GOOGLE_WEBHOOK_SECRET`	Bearer secret Google echoes on notifications	`SECRET_KEY`

Managing subscribers without app credentials (gcloud / console)

If you’d rather not give the app a service account, create and manage the subscriber yourself and leave GOOGLE_SERVICE_ACCOUNT_FILE/GOOGLE_PROJECT_ID unset. The app then needs only GOOGLE_WEBHOOK_SECRET to verify inbound notifications — it never calls the project-level subscriber API.

In this mode the in-app .../webhooks/subscriptions management endpoints (list / register / update / delete) won’t work — they require project credentials. Use the commands below instead.

The endpointAuthorization.secret you set here must equal "Bearer " + the app’s GOOGLE_WEBHOOK_SECRET (which defaults to SECRET_KEY). If they don’t match, every notification fails signature verification and Open Wearables returns 401.

All calls authenticate with your own gcloud identity, which must hold the Health API subscriber role on the project. You can also run these from the Cloud Console API Explorer, but the CLI steps below are easier to copy end-to-end. Use the same subscriberId (open-wearables) the app uses, so it stays interchangeable.

TOKEN=$(gcloud auth print-access-token)
PROJECT=your-project-number   # numeric project number

# Create
curl -X POST \
  "https://health.googleapis.com/v4/projects/${PROJECT}/subscribers?subscriberId=open-wearables" \
  -H "Authorization: Bearer ${TOKEN}" -H "Content-Type: application/json" \
  -d '{
    "endpointUri": "https://YOUR_API_BASE_URL/api/v1/providers/google/webhooks",
    "subscriberConfigs": [
      {"dataTypes": ["steps", "distance", "heart-rate", "sleep", "exercise"], "subscriptionCreatePolicy": "AUTOMATIC"}
    ],
    "endpointAuthorization": {"secret": "Bearer YOUR_GOOGLE_WEBHOOK_SECRET"}
  }'

# List
curl "https://health.googleapis.com/v4/projects/${PROJECT}/subscribers" \
  -H "Authorization: Bearer ${TOKEN}"

# Update the callback URL (endpoint re-verification runs again)
curl -X PATCH \
  "https://health.googleapis.com/v4/projects/${PROJECT}/subscribers/open-wearables?updateMask=endpointUri" \
  -H "Authorization: Bearer ${TOKEN}" -H "Content-Type: application/json" \
  -d '{"endpointUri": "https://NEW_URL/api/v1/providers/google/webhooks"}'

# Delete
curl -X DELETE \
  "https://health.googleapis.com/v4/projects/${PROJECT}/subscribers/open-wearables" \
  -H "Authorization: Bearer ${TOKEN}"

dataTypes above is an abbreviated example — use the set the app supports for webhooks (steps, distance, hydration-log, heart-rate, run-vo2-max, daily-resting-heart-rate, heart-rate-variability, weight, body-fat, blood-glucose, daily-respiratory-rate, sleep, exercise). Registering a data type the app doesn’t handle just means its notifications are ignored.

Next Steps

API Reference

Explore the Open Wearables API endpoints.

Supported Providers

See all supported providers.

Support

Need Help?

Join our Discord and ask a question.
Check GitHub Discussions.
Check the Google Health API Documentation.

Getting started

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Configuration

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Support

Google Health API Integration

Overview

Supported data types

Data delivery

Data granularity and fetch modes

Reconcile vs. list — why it matters

What you need by the end

Prerequisites

Application walkthrough

Webhooks

Webhook subscriber registration

Managing subscribers without app credentials (gcloud / console)

Next Steps

API Reference

Supported Providers

Support

​Overview

​Supported data types

​Data delivery

​Data granularity and fetch modes

​Reconcile vs. list — why it matters

​What you need by the end

​Prerequisites

​Application walkthrough

​Webhooks

​Webhook subscriber registration

​Managing subscribers without app credentials (gcloud / console)

​Next Steps

API Reference

Supported Providers

​Support

Overview

Supported data types

Data delivery

Data granularity and fetch modes

Reconcile vs. list — why it matters

What you need by the end

Prerequisites

Application walkthrough

Webhooks

Webhook subscriber registration

Managing subscribers without app credentials (gcloud / console)

Next Steps

Support