14 wearable APIs, one integration

Cloud OAuth · OAuth 2.0 authorisation code

The Oura Ring API (v2) is one of the cleaner wearable APIs to work with — the documentation is accurate and the daily-summary endpoints are stable. The complexity is not in reading it, it is in keeping it read: Oura backfills and revises data after the fact, so a sleep record you fetched this morning can legitimately change by this evening.

Sleep stages & sleep score · Readiness score · HRV (rMSSD) · Resting heart rate · +4

Cloud OAuth · OAuth 2.0 authorisation code

WHOOP's developer API exposes the four objects the product is built around — cycles, recovery, sleep and workouts. The data is high quality and the model is coherent, which makes WHOOP a favourite for recovery and readiness products.

Recovery score · Strain · Sleep stages & sleep performance · HRV · +4

Cloud OAuth · OAuth 2.0 with PKCE

Fitbit has the largest installed base of any dedicated wearable, which makes it the provider most consumer health products need first. It is also the API with the most historical baggage — the surface has accreted since 2011 and it shows in inconsistent date handling and endpoint shapes.

Steps · Sleep stages · Heart rate (intraday where granted) · Calories · +3

Cloud OAuth · OAuth 2.0 authorisation code

Strava is the best-instrumented activity API in the consumer space and the only provider in the WearLink catalogue with a true push model — an activity upload triggers a webhook within seconds, not on a poll cycle. If your product cares about workouts rather than sleep or recovery, Strava is usually the fastest path to a working demo.

Activities & workouts · GPS routes · Heart rate streams · Power & cadence · +2

Cloud OAuth · OAuth 2.0 authorisation code

Withings is the connected-scale and blood-pressure provider, which makes it the one that matters most for clinical-adjacent products — weight management, hypertension programmes, GLP-1 follow-up and remote patient monitoring. Its data is measurement-shaped rather than continuous: discrete readings taken when a user steps on a scale or straps on a cuff.

Weight & body composition · Blood pressure · Sleep · Heart rate · +1

Mobile SDK · On-device user permission per data type

Apple Health has no cloud API and never has. Apple does not operate a server you can call — HealthKit is an on-device framework, and the only way to get the data is to run code inside an iOS app the user has installed and granted permission to.

Steps · Heart rate · Workouts · Activity rings · +1

Mobile SDK · On-device Android permissions

Health Connect is Android's on-device health data store and the successor to Google Fit. This matters urgently: the Google Fit APIs have been deprecated, and products still calling them are on a clock.

Steps · Heart rate · Sleep · Workouts · +1

Mobile SDK · On-device permissions

Samsung Health matters in proportion to Galaxy's market share, which in India and much of Asia is substantial. Galaxy Watch users are a meaningful population that a Fitbit-and-Oura-only integration misses entirely.

Steps · Heart rate · Sleep · Workouts

Cloud OAuth · OAuth 1.0a — Garmin has not moved to OAuth 2.0 for the Health API

Garmin has the broadest data surface of any provider in the catalogue — if a metric exists in consumer wearables, a Garmin device probably measures it. For endurance, military, occupational-health and research use cases it is frequently non-negotiable.

Steps & daily activity · Sleep stages · HRV · Stress & body battery · +5

Cloud OAuth · OAuth 2.0 authorisation code

Polar's AccessLink API serves a smaller but committed base — endurance athletes, coaching platforms and sports-science teams. Heart rate quality is the reason people choose it; Polar's chest straps remain a reference standard.

Training sessions · Heart rate · Steps · Calories · +1

Cloud OAuth · OAuth 2.0 authorisation code

Suunto is an outdoor and dive-focused brand whose cloud API centres on workout files. For mountaineering, trail and diving products it covers device categories nobody else in this list reaches.

Workouts · Heart rate · HRV · Steps · +3

Cloud OAuth · Partner API credentials

Ultrahuman is the India-headquartered smart-ring maker and the provider most relevant to South Asian consumer health products, where its installed base is meaningful in a way it is not elsewhere.

Sleep · HRV · Resting heart rate · Steps · +3

Cloud OAuth · OAuth 2.0 authorisation code

Dexcom is continuous glucose monitoring, and it is the provider whose data is most directly clinical. Interest has grown sharply beyond diabetes care — metabolic health, GLP-1 programmes and performance nutrition products all want CGM traces.

Continuous blood glucose · Glucose trend & rate of change · Calibration events · Device events

Cloud OAuth · Account credentials against the client API

Eight Sleep measures sleep from the mattress rather than the wrist, which produces a genuinely different signal: no compliance problem, no charging gap, and thermal data no wearable can supply.

Sleep stages · Bed & ambient temperature · HRV · Respiratory rate · +1