Site index
Every page on AIFitnessAPI, in one place.
Main
Fitness & workout APIs
- Best Fitness & Workout APIs (guide + hub)
- The Best Exercise Database APIs for Developers (2026)
- The Best Wearable Fitness & Health-Data APIs (2026)
- The Best Health-Data Aggregator APIs (2026)
- The Best AI Workout & Motion-Tracking APIs (2026)
- The Best Nutrition & Food Database APIs (2026)
- Free & Open-Source Fitness APIs (2026)
- Apple HealthKit vs Google Health Connect (2026)
- Terra vs Vital (Junction): Health-Data APIs Compared (2026)
- Fitbit API vs Garmin API (2026)
- Fitness API vs Building Your Own: How to Decide (2026)
Guides — adding AI workout tracking
- How to Add AI Workout Tracking to Your App (guide + hub)
- Camera Pose Tracking for Fitness Apps: A Practical Guide
- How to Add Rep Counting to Your Fitness App
- How to Add Real-Time Form Feedback to a Workout App
- How to Track Workouts Without a Wearable (Camera-Only)
- How to Add AI Workout Tracking to an iOS App (Swift)
- How to Add AI Workout Tracking to an Android App (Kotlin)
- How to Add AI Workout Tracking to a React Native App
- How to Add AI Workout Tracking to a Flutter App
- How to Add AI Workout Tracking to a Web App (JavaScript)
- How to Improve Pose-Detection Accuracy in Your App
Build guides — by app type
- How to Build a Workout App (guide + hub)
- How to Build a Home Workout App (2026)
- How to Build an AI Fitness Coaching App (2026)
- How to Build a Strength Training App (2026)
- How to Build a Running App (2026)
- How to Build a Yoga App (2026)
- How to Build a Personal Training App (2026)
- How to Build a Physical Therapy / Rehab App (2026)
- How to Build a Corporate Wellness App (2026)
- How to Build a Nutrition Tracking App (2026)
- How to Choose a Tech Stack for a Fitness App (2026)
Integration guides — by provider
- How to Integrate a Fitness or Health API (guide + hub)
- How to Integrate Apple HealthKit (2026)
- How to Integrate Google Health Connect (2026)
- How to Integrate the Fitbit API (2026)
- How to Integrate the Strava API (2026)
- How to Integrate the Garmin API (2026)
- How to Integrate the Oura API (2026)
- How to Integrate the WHOOP API (2026)
- How to Integrate Terra (Health-Data Aggregator) (2026)
- How to Integrate the Nutritionix API (2026)
- How to Integrate the ExerciseDB API (2026)
Troubleshooting — common API errors
- Fitness & Health API Troubleshooting (guide + hub)
- Why Is My Fitness API Returning 401 Unauthorized?
- How to Fix the OAuth redirect_uri Mismatch Error
- Why Is My Fitness API Refresh Token Not Working?
- How to Fix Fitbit API 429 (Rate Limit) Errors
- Why Is HealthKit Returning No Data?
- Why Is Google Health Connect Returning No Data?
- Why Is My Strava Webhook Not Firing?
- Why Is Wearable Data Missing or Delayed?
- Can't Get Garmin API Access? Here's What's Going On
- Google Fit API Is Deprecated — What to Use Instead
Concepts — explained
- Fitness & Health API Concepts (guide + hub)
- What Is a Fitness API?
- What Is a Health-Data Aggregator?
- On-Device vs Cloud Health Data: What's the Difference?
- What Is OAuth 2.0 (and How Health APIs Use It)?
- What Are Webhooks (and Why Fitness APIs Use Them)?
- What Is Pose Estimation (for Fitness Apps)?
- What Is HRV (Heart Rate Variability)?
- What Is VO2 Max (and How Do Wearables Estimate It)?
- What Are Sleep Stages (Awake, Light, Deep, REM)?
- How Do Fitness Apps Estimate Calories Burned?
Alternatives — by product
- Fitness & Health API Alternatives (guide + hub)
- The Best Fitbit API Alternatives (2026)
- Google Fit API Alternatives (It's Deprecated) (2026)
- Garmin API Alternatives When You Can't Get Access (2026)
- The Best Strava API Alternatives (2026)
- The Best Oura API Alternatives (2026)
- The Best WHOOP API Alternatives (2026)
- Apple HealthKit Alternatives (2026)
- The Best Terra (tryterra.co) Alternatives (2026)
- The Best Nutritionix Alternatives (2026)
- The Best ExerciseDB Alternatives (2026)
Compliance & privacy
- Health-Data Compliance & Privacy for Fitness Apps (guide + hub)
- Does My Fitness App Need to Be HIPAA Compliant?
- GDPR for Fitness Apps: What Developers Need to Know
- Is Fitness Data PHI? PII, PHI, and Health Data Untangled
- Does the FDA Regulate Fitness Apps?
- Apple App Store Health Data Rules: What You Need to Ship a HealthKit App
- What does Google Play's health data policy require?
- How to Store Health Data Securely
- How to Get Valid User Consent for Health Data
- What Does a Fitness App Privacy Policy Need to Include?
- Health Data Retention and Deletion: A Developer's Guide
Migrations
- Fitness & Health API Migration Guides (guide + hub)
- How to migrate from Google Fit to Health Connect
- Migrating from the Fitbit Web API to the Google Health API
- Adding Android to a HealthKit app
- Consolidate wearables: replace direct integrations with one aggregator
- Migrate from an aggregator to direct provider integrations
- How to switch from one health data aggregator to another
- Migrate from polling to webhooks for a fitness API
- Adapting Your Integration to Strava's API Changes
- Keep Users Connected During a Fitness API Migration
- Migrate off a deprecated fitness API
Pricing
- Fitness & Health API Pricing (guide + hub)
- Fitbit API Pricing: What Does It Actually Cost?
- Garmin API Pricing: What Does It Actually Cost?
- Strava API Pricing: What Does It Actually Cost?
- Oura API pricing: what it actually costs
- WHOOP API Pricing: What Does It Actually Cost?
- Health data aggregator API pricing: how Terra, Junction, Rook, and Spike charge
- What does a nutrition API cost?
- Exercise Database API Pricing: What Does It Cost?
- Are Fitness APIs Free? An Honest Overview
- How Much Does a Fitness API Cost?
Comparisons
- Fitness & Health API Comparisons (guide + hub)
- Oura vs WHOOP: Which API for Your App?
- Fitbit vs Apple Watch: Which for Your App?
- Strava vs Garmin: Which API for Your App?
- Fitbit vs Oura API: Which for Your App?
- WHOOP vs Garmin: Which for Your App?
- Terra vs ROOK: Which Aggregator API for Your App?
- Terra vs Spike Health: Which Aggregator for Your App?
- Nutritionix vs Edamam: Which Nutrition API to Use?
- Edamam vs Spoonacular: Which Nutrition API?
- ExerciseDB vs wger: Which Exercise API for Your App?
Health data by metric
- Health Data by Metric (guide + hub)
- Heart Rate API: How to Get Heart-Rate Data Into Your App
- HRV API: How to Get Heart Rate Variability Data
- VO2 Max API: How to Get VO2 Max Data
- Blood Oxygen (SpO2) API: How to Get SpO2 Data
- Sleep Tracking API: How to Get Sleep Data Into Your App
- Step Counting API: How to Get Step Data
- Workout Detection API: Get Recorded Workout Sessions
- GPS Activity API: How to Get Route Data from Workouts
- Calorie Tracking API: How to Get Calorie Data
- Body Composition API: Weight, Body Fat, and Lean Mass Data
AI motion & pose estimation
- AI Motion & Pose Estimation (guide + hub)
- Pose Estimation Models Compared: MediaPipe, MoveNet, YOLO and More
- 2D vs 3D Pose Estimation for Fitness Apps
- Pose Estimation Accuracy: What It Means and What Drives It
- Multi-Person Pose Tracking: Top-Down vs Bottom-Up
- On-Device vs Cloud Pose Estimation: Which to Choose
- Real-Time Pose Estimation: Frame Rate, Latency, and Model Trade-offs
- Pose Estimation Hardware Requirements: What You Actually Need
- How Rep Counting Works: The Algorithm Explained
- How Camera-Based Form Feedback Works
- Build vs Buy: AI Motion Tracking
AI & LLM features
- AI & LLM Features for Fitness Apps (guide + hub)
- AI Workout Plan Generation: How to Build One That Ships
- AI Food Logging: Text and Photo Nutrition Entry That Actually Works
- Personalizing Your App With a User's Own Wearable Data
- Grounding an LLM in Your Exercise Database
- Writing the System Prompt for an AI Fitness Coach
- AI vs Rules-Based Coaching: Where a Language Model Actually Helps
- How to Evaluate an AI Fitness Feature
- Guardrails for an LLM That Gives Fitness Advice
- Choosing an LLM for a Fitness App: Pick by Job, Not by Leaderboard
- What Does an AI Fitness Feature Cost to Run?
Health data architecture
- Health Data Architecture for Fitness Apps (guide + hub)
- Incremental Sync: Reading Only What Changed Since Last Time
- Backfilling Years of Wearable Data Without Hitting Rate Limits
- Background Sync That Does Not Depend on the Phone Waking Up
- Webhook ingestion for health data: making at-least-once delivery safe
- Mapping Users to Wearable Provider Accounts and Devices
- Deduplicating Health Data From Multiple Sources
- Normalizing wearable data across providers
- Timezones and Day Boundaries: Whose Midnight Defines the Day?
- Missing Data and Gaps in Health Metrics
- How Should You Store Health Time-Series Data?
- Resolving Sync Conflicts in an Offline-First Workout Log
- Versioning Derived Metrics and Recomputing Health History
- Monitoring a Health Data Pipeline for Silent Failures
- Deleting and Exporting a User's Health Data