Mobile & Cross-Platform2024 - 2025Lead Full-Stack Mobile Architect

PulseFit - Cross-Platform Mobile SaaS App

End-to-End Flutter iOS & Android App with Node.js REST API Backend

Platform Target

iOS & Android

Single Flutter codebase

API Response Time

14ms P99

Node.js REST API backend

App Store SLA

100%

Passed Apple & Google review

Active User Rating

4.9 / 5.0

60fps smooth animations

Technology Stack & Tools Used

FlutterDartNode.jsExpress.jsPostgreSQLRedisStripe APIFirebase FCMDocker

Architectural Overview & System Boundaries

PulseFit features a Flutter mobile frontend utilizing BLoC pattern for state management and local Hive storage for offline data synchronization. The frontend communicates with a scalable Node.js & Express REST API hosted on AWS, backed by PostgreSQL and Redis caching for instant user telemetry sync.

Core Engineering Challenges

1Maintaining 60fps rendering performance during real-time data sync bursts on low-spec Android devices.

2Offline-first state synchronization without creating duplicate server records.

3Cross-platform Stripe payment sheet integration across iOS and Android.

Critical Architectural Decisions & Trade-Offs

BLoC Pattern & Offline Hive Local Cache

Users lose network connectivity in gym environments. Implementing BLoC with local Hive key-value storage allowed seamless offline data logging with background queue sync.

Impact: Zero data loss for offline users and instant sub-10ms UI state transitions.

Node.js JWT & Webhook Subscription Engine

Handling recurring in-app subscriptions required secure server-side validation. Built a Node.js webhook worker to verify Stripe and Apple/Google receipts.

Impact: 100% accurate billing reconciliation and automated entitlement updates.

### Background & Engineering Vision Building a modern subscription mobile product requires both a fluid, high-frame-rate user interface and a secure, low-latency backend. As Lead Mobile Architect, I engineered PulseFit using Flutter for cross-platform efficiency coupled with a Node.js REST API. ### Mobile Architecture & Integration 1. **Flutter Mobile Frontend**: Built with Dart using strict BLoC state management, custom animation controllers, and responsive layout builders for phone and tablet form factors. 2. **Node.js REST Backend**: Express.js backend API with JWT authentication, rate limiting, and PostgreSQL relational database schemas. 3. **Push Notifications & Analytics**: Firebase Cloud Messaging (FCM) triggers automated re-engagement notifications based on user activity events. 4. **App Store Deployment**: Automated CI/CD pipelines via GitHub Actions building signed release APK/AAB and IPA binaries for Play Store and App Store release.

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