6 min read
The Fitness API Cost Your Users Pay
5 of 24 products bill your end user, not you. All five are direct wearable integrations, and the hardware requirement, not your budget, sets your reach.
wearablescostapi
For builders in health, wellness & fitnessPick the right fitness API.
Pick the right fitness API.
Ship without the surprises.
Wearables, health data, nutrition, AI motion tracking — compared, priced, and documented down to the failure modes, with the deprecations and deadline traps called out before they cost you a rewrite.
- 276+
- verified guides & comparisons
- 21
- topic hubs, hero to edge case
- 6
- CI-tested code recipes
- CC BY
- open datasets, free to reuse
Start where you are
I’m choosing an API
Compare the field by the job you’re hiring for — data coverage, pricing model, approval gates — before you write a line of integration code.
I’m building AI features
Camera rep counting, form feedback, LLM coaching — the whole pipeline from pose model or SDK choice to guardrails, latency, and cost.
Something broke — or a deadline looms
401s, dead webhooks, empty reads — symptom-to-fix pages. And when a platform is being retired, the dated migration playbook is already written.
Popular APIs & SDKs
All integration guides →Apple HealthKitOn-device · iOS
No OAuth, no servers — and read-denial is invisible by design. The full Swift integration guide.Read the guide Google Health ConnectOn-device · Android
The successor to Google Fit on Android: permissions, the 30-day read window, and the quirks.Read the guide Fitbit Web APITurndown reported 2026
Still widely integrated, now on the clock. The guide, plus the migration path to Google's cloud API.Read the guide Strava APICloud · OAuth
Activities, segments, and webhooks — under developer terms that have tightened. What's still allowed.Read the guide Garmin Health APICloud · approval-gated
Deep wearable data behind a developer-program approval. How to apply, integrate, and pass review.Read the guide Oura APICloud · OAuth
Sleep, readiness, and HRV from the ring — including the personal-access-token deprecation.Read the guide WHOOP APICloud · OAuth
Recovery, strain, and sleep via OAuth — and what changed in the developer platform restructure.Read the guide TerraAggregator
One integration, many wearables. When an aggregator earns its fee — and when direct is better.Read the guide Polar AccessLinkCloud · OAuth
Training, sleep, and recharge data from Polar devices — registration through webhooks.Read the guide NutritionixNutrition
Natural-language food logging and a large verified food database — pricing model included.Read the guide MediaPipe, MoveNet & pose modelsOpen-source models
The open pose-estimation stacks compared: accuracy, platforms, and maintenance status.Read the guide AI motion SDKsKinesteX · Sency · QuickPose
Camera-based rep counting and form feedback as a product decision: build on models or buy an SDK.Read the guide Free tools — no signup needed
API Directory
One page per API: how it bills you, what your users must own, what gates launch.
Browse itAPI Picker
Three questions, a tailored recommendation with next steps — and the reasoning shown.
Try itCost Planner
Model what your stack costs at your user count — every price traced to its source.
Plan costsType Matrix
Every metric’s HealthKit ↔ Health Connect type — and where they quietly disagree.
Open itDay-Boundary Demo
Watch a naive daily rollup break on DST and timezones — interactively, then fix it.
See it breakReference — read from the platforms’ own documentation
Generated, not written. Every value below is read from Apple’s documentation JSON or verified against both platforms’ docs, and regenerating the dataset updates every page that cites it.
All 240 HealthKit types
Quantity, category, characteristic and workout identifiers — with units, availability, and whether you sum or average each one.
Open the referenceAll 17 HealthKit errors
What each failure means — including why a denied read raises no error at all, and returns an empty result instead.
Open the referenceHealthKit ↔ Health Connect
The cross-platform mapping for the metrics we verified on both, and the pairs that look equivalent but are not.
Open the referenceVerified in the last 30 days
The full tracker →100 of 276 pages were re-checked against their sources in the last 30 days, and these are the most recently verified entries in the changes tracker. Both numbers are computed at build time from the pages themselves — if we stop doing the work, this section says so.
Everything we cover
Full site index →Fitness & workout APIs10 guides
Compare and choose an API by the job — exercise content, wearables, aggregators, nutrition, or AI motion tracking.Newest verified 2026-08-02Add AI workout tracking11 guides
The capture → pose → interpret pipeline: camera pose, rep counting, form feedback, and per-platform wiring.Newest verified 2026-08-11Build a workout app24 guides
End-to-end build playbooks by app type — home workout, coaching, strength, running, rehab, and more.Newest verified 2026-09-04Integration guides11 guides
Register, OAuth, fetch, and webhooks — a hands-on guide per provider, from HealthKit to Terra.Newest verified 2026-08-12Troubleshooting25 guides
Symptom-to-fix for the common errors: 401s, rate limits, empty data, dead webhooks, and OAuth snags.Newest verified 2026-09-04Concepts explained13 guides
Plain-English explainers for the health-tech vocabulary — OAuth, aggregators, HRV, VO2 max, and more.Newest verified 2026-08-12Alternatives11 guides
Anchored on one product: why teams look to switch, and the realistic options — with links to the comparisons.Newest verified 2026-08-02Compliance & privacy10 guides
Which rules apply — HIPAA, GDPR, FDA, app-store policy — and how to build for consent, storage, and deletion.Newest verified 2026-07-14Migration guides10 guides
Step-by-step playbooks for moving an integration — Google Fit to Health Connect, direct-to-aggregator, and more.Newest verified 2026-07-20Pricing11 guides
What fitness and health APIs really cost — which are free to call, which charge, and what drives your bill.Newest verified 2026-08-12Comparisons17 guides
Head-to-heads through the developer lens — Oura vs WHOOP, Fitbit vs Apple Watch, Terra vs Rook, and more.Newest verified 2026-08-12Health data by metric14 guides
Which API gives you each metric — heart rate, steps, sleep, calories, HRV, VO2 max — and measured vs estimated.Newest verified 2026-08-12AI motion & pose estimation13 guides
The tech behind camera fitness — pose models, 2D vs 3D, on-device vs cloud, rep counting, and form scoring.Newest verified 2026-08-02AI & LLM features11 guides
Plan generation, natural-language food logging, coaching prompts — plus guardrails, model choice, and cost.Newest verified 2026-08-12Health data architecture15 guides
The layer after the integration works — dedupe, normalization, timezones, sync, storage, and data quality.Newest verified 2026-08-12Testing health apps14 guides
HealthKit has no test double, CI cannot fire background delivery, the simulator has no camera. What to do instead.Newest verified 2026-07-27Cookbook: tested code6 guides
Runnable, dependency-free reference implementations — token rotation, webhooks, DST-safe rollups — CI-tested.Newest verified 2026-08-12Connected devices12 guides
Straps, treadmills, trainers, and the watch as a live sensor — BLE heart rate, FTMS, and the testing story.Newest verified 2026-08-14Engagement & retention14 guides
Getting people back: notifications, Live Activities, widgets, streaks, leaderboards — and measuring lift honestly.Newest verified 2026-08-22Watch apps12 guides
Writing the app on the wrist: workout sessions, background execution, WorkoutKit, Wear OS tiles, battery, testing.Newest verified 2026-08-22Why builders trust this site
Sourced, or it doesn’t ship
Every price, limit, and deadline traces to a primary source checked when the page was written. When we can’t verify a claim, the page says so instead of rounding up to certainty. How we verify →
Dates graded, not sharpened
The changes tracker labels every deadline confirmed— vendor’s own words, quoted — or reported, and keeps each date at the precision its evidence supports. See the tracker →
Code that actually runs
Cookbook recipes are dependency-free files with node:test suites, run in CI on every change — the code on the page is a byte-verbatim copy of the file that passed. Open the cookbook →
Funding, disclosed
KinesteX, an AI motion SDK, funds this site. Every page that features it says so in a banner like this one, our comparisons list where its competitors win, and nothing here ever crowns the sponsor. Read the rules we follow →
Annual report
The State of Fitness APIs 2026
The year the free ride ended: shutdowns, paywalls, and model freezes across the ecosystem — what changed, what it costs now, and where the risk sits next.
Read the report →The data behind it is open
Pricing, access models, and status for the ecosystem in one dataset — CC BY 4.0, so you can cite it, load it, or build on it.
On the clock — next deadlines
Full tracker →September 2026reported
Fitbit Web API turndown (reported window)The legacy Fitbit Web API's retirement in favour of the cloud Google Health API is reported to land around September 2026. No official day is confirmed on a page we could verify; some third-party guides name September 30, which is weaker evidence, not stronger. Tokens are reported not to transfer — every user re-consents via Google OAuth.Fitbit API shutdown center September 2026reported
Fitbit → Google Health side-by-side window reported to closeA window in which the legacy Fitbit Web API and the Google Health API run side by side is reported to extend into late September 2026 — the practical dual-read period for migrating integrations.Fitbit → Google Health migration playbook December 2026confirmed
Google Fit APIs: end of documented supportGoogle's own documentation states Fit APIs "will be supported until the end of 2026" (verified against developer.android.com on July 31, 2026). Migration targets differ by integration shape: Health Connect on-device, Health Services on Wear OS, or the Google Health API for server-side reads.Google Fit shutdown hub When a reported date firms up or a term changes, subscribers hear first — with the source, not the panic. Join them below ↓
Latest writing
View all →6 min read
Ten Health Metrics, Two Platforms
We checked 10 metrics against Apple's and Google's own docs. Every one exists on both. The shapes don't match, and that is the part that costs you.
healthkithealth-connectdata
7 min read
Your HealthKit Bridge Last Shipped in 2024
The main React Native HealthKit bridge last released in October 2024. Its Android counterpart cut five versions in one week this August.
healthkithealth-connectecosystem
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Sign up and the downloads appear instantly: the API selection checklist, the launch compliance checklist, the motion-SDK scorecard, and the full 2026 dataset. After that, one email when something actually changes — a deadline, a term, a deprecation. No fluff, no spam.
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- ✓ Motion-SDK scorecard (CSV)
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