
Mobile App
Flutter (Dart) - iOS & Android
Single codebase compiled to native iOS and Android binaries. Supports dark/light modes, offline SQLite database, and native platform channels for HealthKit and Google Fit integration.

Web Dashboard
React.js + Next.js
Coach and admin web experience built with Next.js for server-rendered performance, plus a marketing surface for new sign-ups. Shares the design system and brand tokens with the mobile app.

Backend
Node.js + Express + OAuth 2.0
REST APIs for authentication, workout catalog, personalization engine, progress tracking, social feed, and analytics. OAuth 2.0 with refresh-token rotation for Apple, Google, and wearable integrations.

Database
PostgreSQL
Relational database for user accounts, activity history, workout programs, progress metrics, and social data. Backup and recovery configured on AWS.

Cloud Infrastructure
AWS (S3 + CloudFront + EC2)
S3 for workout video and asset storage, CloudFront CDN for global distribution, EC2 for application hosting. VPC and security groups enforce network isolation.

AI & Personalization
ChatGPT (OpenAI) + Google Gemini
Dual-model AI layer for personalized workout recommendations, conversational coaching prompts, and meal-plan generation. Prompts route to the model best suited per task with graceful fallback.

Wearable APIs
Apple HealthKit, Google Fit, Garmin Connect, Fitbit Web API, Strava API
Native iOS HealthKit framework, Android Google Fit SDK, and REST APIs for Garmin, Fitbit, Strava. Bidirectional data sync with conflict resolution.

Real-Time & Notifications
Firebase
Push notifications for workout reminders, social interactions, and achievement badges. Firebase Auth as backup for user sessions.

Maps & GPS
Google Maps SDK + Apple Maps
GPS tracking for outdoor activities (running, cycling, hiking). Route mapping, elevation profiles, and location-based recommendations.

Payment
Apple In-App Purchase + Google Play Billing + Stripe
Handles premium subscription tiers, in-app purchases for premium content, and Stripe for web-based billing and invoicing.

API & DevOps
Postman + Swagger + GitLab
Postman for API testing and shared collections, Swagger for OpenAPI 3.1 contract documentation, GitLab for source control and CI/CD pipelines with automated builds for both web and mobile.

Design
Figma
UI/UX design system, high-fidelity mockups, interactive prototypes, and developer handoff documentation.