Cross-Platform Mobile App Engineering | React Native & Expo
Building high-performance, offline-first native mobile applications from a unified codebase.
Building individual apps for iOS and Android doubles code maintenance overhead and fragments product deployment. I engineer high-performance cross-platform mobile apps utilizing modern Expo ecosystems while retaining the ability to write custom native bridges (Swift, Kotlin) for deep device-level hardware mapping. My systems feature robust offline-first caching architectures built on C++ speed layers like MMKV and local SQLite configurations, keeping interfaces completely responsive under any network constraint. From advanced push notification delivery pipelines via Firebase Cloud Messaging to secure biometric authorization (FaceID/TouchID) and rigorous App Store / Google Play runtime compliance compliance, I cover the entire publishing path.
Who This Is For
Founder Launching on iOS & Android Simultaneously
Pain point: Can't afford two separate native teams for one product
Outcome: One codebase shipping to both app stores without feature parity gaps
Product Team Needing Offline Reliability
Pain point: Users lose data or see broken UI when connectivity drops
Outcome: Offline-first architecture that keeps the app fully usable without a network connection
Existing Web App Going Mobile
Pain point: Web product works but no mobile presence exists
Outcome: Native-feel mobile app sharing business logic with the existing web stack where possible
What This Solves
Problem: AsyncStorage causes UI jank on large local datasets
Impact: Sluggish interactions that make the app feel unpolished
Solution: MMKV storage with JSI bindings for near-instant read/write, no async bridge overhead
Problem: Long lists of items cause frame drops and memory spikes while scrolling
Impact: Poor perceived performance, especially on lower-end Android devices
Solution: FlashList view recycling combined with memoized components and off-thread data filtering
Problem: Native feature updates require a full app store review cycle even for minor fixes
Impact: Days of delay shipping urgent bug fixes to users
Solution: Expo Updates for OTA delivery of JS-layer fixes, reserving store review only for native runtime changes
Key Technologies & Platforms Used
Offline-First Architecture Explained
The app is built to be fully functional with zero connectivity, syncing seamlessly the moment a connection returns.
Local Storage
MMKV and SQLite handle structured local data at native speed
MMKV's C++ core interfaces directly via JSI, avoiding the async bridge serialization that makes AsyncStorage slow on large datasets
Sync Layer
Changes queue locally and reconcile automatically on reconnect
A conflict-resolution queue timestamps local writes and replays them against the server once connectivity is restored
Native Bridging
Custom Swift/Kotlin modules handle device-level features Expo doesn't cover
Config plugins wrap native code so builds stay reproducible without ejecting from the managed Expo workflow
Scope of Deliverables
- Custom cross-platform mobile application development using React Native & Expo
- Native platform modules bridging for specialized iOS & Android hardware access
- High-speed, offline-first architectures utilizing MMKV & SQLite caching
- Secure biometric authentication integration (FaceID, TouchID, Android Fingerprint)
- Interactive push notification infrastructure using Firebase Cloud Messaging (FCM)
- Advanced performance tuning, main-thread fluid animations, and memory leak resolution
- Complete app store submission management for Apple and Google platforms
Let’s Build Something Exceptional Together
Every project I take on is managed and delivered using high-performance engineering workflows and industry-standard project frameworks. I don't just write code; I establish production-grade technical scaffolding that ensures your application is scalable, maintainable, and built to last.
Engineering Workflows & Delivery Guarantees:
- •Transparent Asynchronous Execution: Active project tracking via Jira & Linear with structured, data-driven sprint cycles.
- •Rigorous MVP Prioritization: Enforcing strict MoSCoW parameters to maximize features while eliminating budget waste.
- •Industrial-Grade Automation: Event-driven backend workflows and custom API integrations built on FastAPI, Node.js, and Python.
- •Modern Elite Stack Integration: Type-safe, ultra-fast applications engineered with Next.js, React, Node.js, and Python.
- •Full IP Ownership: You retain 100% ownership of the GitHub repositories, containerized Docker environments, and cloud infrastructure setups created.
Frequently Asked Questions
Get technical answers to common questions about this service, operational workflows, and delivery mechanics.
When do you choose an Expo workflow over a Bare React Native project structure?
Why do you use MMKV storage for local application caching instead of traditional AsyncStorage?
How do you guarantee smooth 60FPS scrolling performance when rendering large data lists?
What is your approach to handling seamless over-the-air (OTA) application updates in production?
How do you implement secure biometric user authentication on iOS and Android devices?
How do you prevent UI layouts from shifting across different mobile screen sizes and aspect ratios?
What is your workflow for configuring push notification categories and interactive button actions?
How do you diagnose and resolve memory leaks in production React Native applications?
What steps do you take to secure sensitive API access tokens stored on mobile devices?
How do you ensure application compliance with strict Apple App Store Review guidelines?
Client Success & Feedback
Read feedback and ratings from verified client projects delivered on Upwork, Fiverr, and directly.
“Bhalli's offline-first setup works flawlessly. Our active users log workouts entirely offline, and their progress data syncs perfectly to our databases the split-second they reconnect.”