How do you integrate a fitness API?

Most fitness data APIs follow the same shape: register a developer app to get credentials, send the user through an OAuth 2.0 consent flow to get an access token, call the data endpoints with that token, and refresh the token when it expires. Many providers also offer webhooks so you're notified of new data instead of polling. The on-device platform stores (Apple HealthKit, Google Health Connect) are the exception — they use per-data-type OS permissions, not OAuth.

Do fitness APIs use OAuth?

Most cloud/wearable APIs (Fitbit, Strava, Garmin, Oura, WHOOP) use OAuth 2.0 with per-user consent. Aggregators like Terra broker that OAuth for many providers behind one integration. Apple HealthKit and Google Health Connect are on-device and use OS permission prompts rather than OAuth. Content APIs (ExerciseDB) and some nutrition APIs use a simple API key.

Which fitness API is easiest to integrate?

API-key REST services (exercise content, some nutrition APIs) are the quickest to get a first call working. OAuth wearable APIs add a consent flow and token refresh, and several (Garmin, WHOOP, Fitbit) require you to apply for production access. On-device stores need platform-specific native code. Pick based on the data you need, not just integration ease.

Integration Guides

How to Integrate a Fitness or Health API

Most fitness data APIs follow one pattern: register a developer app, send the user through an OAuth 2.0 consent flow for an access token, call the data endpoints with it, and refresh the token when it expires — with webhooks for new-data notifications. The on-device platform stores (Apple HealthKit, Google Health Connect) are the exception, using OS permissions instead. These guides walk each provider end to end.

The shared integration pattern

Before the per-provider specifics, it helps to see the shape almost all of them share:

Register a developer app with the provider to get a client ID/secret (and, for several, apply for production access).
Run the OAuth 2.0 flow — redirect the user to consent, receive an authorization code, exchange it for an access + refresh token.
Call the data endpoints with the access token to read activity, heart rate, sleep, workouts, and so on.
Handle refresh and webhooks — refresh expiring tokens, and subscribe to webhooks so you react to new data instead of polling.

Not sure which provider to integrate in the first place? Start with the fitness API landscape to choose by category, or the head-to-heads like Fitbit vs Garmin. If you want camera-based tracking rather than device data, see the AI workout tracking guides instead.

Auth flows, scopes, endpoints, and access requirements change — and some providers are mid-migration. Each guide notes this; always confirm the current details in the provider’s official documentation before you ship.

Platform health stores

On-device, per-OS permission (not OAuth).

Wearables & activity

OAuth 2.0, per-user consent, often partner approval.

Aggregators

One integration, many devices.

How to Integrate Terra (Health-Data Aggregator) (2026)Integrate Terra once to read Garmin, Fitbit, Oura, Whoop, and 500+ wearables via one normalized webhook. Widget session, payloads, and signature checks.

Content & nutrition

API-key REST — the simplest to start.

Frequently asked questions

How do you integrate a fitness API?: Most fitness data APIs follow the same shape: register a developer app to get credentials, send the user through an OAuth 2.0 consent flow to get an access token, call the data endpoints with that token, and refresh the token when it expires. Many providers also offer webhooks so you're notified of new data instead of polling. The on-device platform stores (Apple HealthKit, Google Health Connect) are the exception — they use per-data-type OS permissions, not OAuth.
Do fitness APIs use OAuth?: Most cloud/wearable APIs (Fitbit, Strava, Garmin, Oura, WHOOP) use OAuth 2.0 with per-user consent. Aggregators like Terra broker that OAuth for many providers behind one integration. Apple HealthKit and Google Health Connect are on-device and use OS permission prompts rather than OAuth. Content APIs (ExerciseDB) and some nutrition APIs use a simple API key.
Which fitness API is easiest to integrate?: API-key REST services (exercise content, some nutrition APIs) are the quickest to get a first call working. OAuth wearable APIs add a consent flow and token refresh, and several (Garmin, WHOOP, Fitbit) require you to apply for production access. On-device stores need platform-specific native code. Pick based on the data you need, not just integration ease.

Independent comparison, last reviewed July 9, 2026. Pricing, rate limits, and feature availability change often — confirm current details in each provider’s official documentation before you commit. Product and company names are trademarks of their respective owners; AIFitnessAPI is not affiliated with, endorsed by, or sponsored by any product listed here.