Polar API Integration

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Overview

Polar provides access to exercise, daily activity, sleep, and heart rate data from Polar devices through the AccessLink API. The integration uses OAuth 2.0 for authentication and pull-based syncing to fetch data.

Supported data types

Data Type	Support
Workouts / Exercises	Yes (with optional HR samples, zones, route)
Sleep (with stages)	Yes
Daily activity (steps, calories, activity zones)	Yes
Continuous heart rate	Yes
Nightly Recharge / Recovery	Yes
Cardio Load	Yes
Sleepwise Alertness	Yes (requires Polar Sleepwise subscription)
Sleepwise Circadian Bedtime	Yes (requires Polar Sleepwise subscription)
Body Temperature	Yes (requires Polar Elixir device)
Sleep Skin Temperature	Yes (requires Polar Elixir device)
SpO2	Yes (requires Polar Elixir device)
Wrist ECG	Yes (requires Polar Elixir device)

Data delivery

Method	Description
Polling (pull) — Exercises	Open Wearables fetches exercises via the AccessLink v3 API (`/v3/exercises`). Returns all exercises available in Polar Flow for the connected user.
Polling (pull) — 24/7 data	Sleep, daily activity, continuous HR, Nightly Recharge, cardio load, and Elixir/Sleepwise metrics are fetched via range endpoints covering the last 90 days.
Webhooks (push)	Polar sends a lightweight notification on each event (exercise, sleep, activity, etc.). Open Wearables acknowledges immediately and enqueues a targeted sync for the affected data type.

Webhook delivery requires a registered webhook subscription and POLAR_WEBHOOK_SIGNATURE_SECRET set in your environment. See the configuration step below.

What you need by the end

App credentials: Client ID + Client Secret from the Polar AccessLink admin panel
Redirect URI registered in your Polar application

Prerequisites

A Polar Flow account

Application walkthrough

Create a Polar Flow account

If you don’t have one yet, create a free account at flow.polar.com.This is the same account used by Polar device owners - no separate developer account is needed.

Go to the Polar AccessLink Admin and sign in with your Polar Flow credentials.Click Create client to start the registration process. You’ll go through four tabs:1. Contractual Information

Fill in your organization details (name, address, country)
Toggle “I intend to integrate on behalf of a client or third-party organization” if applicable
Accept the AccessLink Limited License Agreement

2. Application Information

Application Name: Your app name (e.g. “Open Wearables”)
Business contact (email): Your contact email
Description: Brief description of your application
Application Web site: Your app’s website (optional)
Authorization redirect URL: Your OAuth callback URL - for local development use http://localhost:8000/api/v1/oauth/polar/callback
Available data types: Enable all three - Exercise data, Daily activity data, Physical information data

3. Check InformationReview the summary of your organization and application details, then click Confirm.4. CredentialsAfter confirmation, you’ll see your:

Client ID
Client Secret

The Client ID and Client Secret are shown only once. Copy and store them immediately. If you lose them, you’ll need to create new credentials from the Admin tool.

Configure credentials in Open Wearables

Add the following to your .env file:

#--- Polar ---#
POLAR_CLIENT_ID=your-polar-client-id
POLAR_CLIENT_SECRET=your-polar-client-secret
POLAR_REDIRECT_URI=http://localhost:8000/api/v1/oauth/polar/callback
# Optional — required only if using webhooks (set automatically on first registration)
POLAR_WEBHOOK_SIGNATURE_SECRET=

Configuration details:

Variable	Description
`POLAR_CLIENT_ID`	Client ID from the Polar AccessLink Admin panel
`POLAR_CLIENT_SECRET`	Client Secret from the Polar AccessLink Admin panel
`POLAR_REDIRECT_URI`	Must match the Authorization redirect URL registered in your Polar application. For local dev: `http://localhost:8000/api/v1/oauth/polar/callback`
`POLAR_WEBHOOK_SIGNATURE_SECRET`	HMAC-SHA256 signing secret returned by Polar on webhook creation. Returned once — save it immediately. Used to verify incoming webhook payloads.

The OAuth scope is hardcoded to accesslink.read_all which grants full read access to the AccessLink API. No additional scope configuration is needed.

Connect a user via OAuth

With credentials configured and your Open Wearables instance running, initiate the OAuth flow to connect a user’s Polar account.1. Get the authorization URL:

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

Response:

{
  "authorization_url": "https://flow.polar.com/oauth2/authorization?client_id=...&redirect_uri=...&response_type=code&scope=accesslink.read_all&state=...",
  "state": "abc123..."
}

2. Redirect the user to the authorization_url. They will log in to Polar Flow and authorize your app.3. Polar redirects back to the callback URI configured in your .env (POLAR_REDIRECT_URI). Open Wearables automatically exchanges the authorization code for access tokens and registers the user with the Polar API.4. Verify the connection was created:

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": "polar" and "status": "active".

The redirect_uri parameter in the authorize call is where the user is sent after the flow completes (e.g., back to your app). This is separate from POLAR_REDIRECT_URI in your .env, which is the server-side OAuth callback that Polar sends the authorization code to.

Sync data

An initial sync is triggered automatically after a successful OAuth connection. To manually sync or fetch data:

# Sync all data types
curl -X POST "http://localhost:8000/api/v1/providers/polar/users/{user_id}/sync?data_type=all" \
  -H "X-Open-Wearables-API-Key: YOUR_API_KEY"

Exercises are fetched from /v3/exercises which returns all exercises available in Polar Flow for the connected user (no date filter). 24/7 data (sleep, activity, HR, etc.) is fetched over a 90-day lookback window using range endpoints.

Verify the integration

Once data has synced, fetch it via the Open Wearables API:

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

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

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

You can also fetch raw Polar exercise data with optional samples, zones, and route data:

# Fetch Polar exercises with HR samples and route
curl -X GET "http://localhost:8000/api/v1/vendor-workouts/polar/users/{user_id}/workouts?samples=true&zones=true&route=true" \
  -H "X-Open-Wearables-API-Key: YOUR_API_KEY"

If data is returned, your Polar integration is working end-to-end.

Rate Limits

Polar AccessLink API uses dynamic rate limits that scale with your registered user count:

Limit	Formula
Per 15 minutes	500 + (registered users x 20)
Per 24 hours	5,000 + (registered users x 100)

Rate limit headers are included in every response: RateLimit-Usage, RateLimit-Limit, RateLimit-Reset.

Next Steps

API Reference

Explore the Open Wearables API endpoints.

Architecture

Understand the overall system architecture.

Support

Need Help?

Join our Discord and ask a question.
Check GitHub Discussions.
Check the Polar AccessLink API Documentation.
Contact Polar developer support: b2bhelpdesk@polar.com

Getting started

Architecture

Health Scores

Providers

Rabts Mobile App

Sync SDK

MCP Server

Developer Guides

Configuration

Support

Overview

Supported data types

Data delivery

What you need by the end

Prerequisites

Application walkthrough

Rate Limits

Next Steps

API Reference

Architecture

Support

​Overview

​Supported data types

​Data delivery

​What you need by the end

​Prerequisites

​Application walkthrough

​Rate Limits

​Next Steps

API Reference

Architecture

​Support

Overview

Supported data types

Data delivery

What you need by the end

Prerequisites

Application walkthrough

Rate Limits

Next Steps

Support