// Hello world, I’m

Fahim MontasirOpi

Flutter Developer · Associate Software Engineer

Flutter developer building production mobile apps, using AI-assisted workflows, with Firebase + Node.js backends — and OTA travel systems as one specialty, not the whole story.

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GitHub LinkedIn Dhaka, Bangladesh

Focus Flutter · AI-Assisted · Firebase · OTACurrently Associate Software Engineer

About

Production Flutter apps, built with AI, backed by Firebase

A practical, product-minded engineer — focused on clean architecture, reliable features, and maintainable code.

I am a Flutter developer. I build production mobile apps with clean architecture and Riverpod, GetX, and BLoC — and ship and maintain them on Google Play and the App Store, with ongoing attention to performance, UX, and maintainability.

I am an expert in AI-assisted development. I use agentic workflows, prompt engineering, function and tool calling, MCP, and AI-assisted review and diagnostics — with Cursor, GitHub Copilot, Claude, GPT-4o, and Gemini — to deliver faster without giving up code quality. AI speeds up the work; human review decides what ships.

On the backend, I work with Firebase — Auth, Cloud Firestore, Cloud Functions, Cloud Messaging, Storage, and Hosting — plus Node.js and TypeScript REST services, and Supabase and PostgreSQL where they fit.

OTA travel is one domain I apply this in: flight, hotel, transfer, insurance, and eSIM booking flows. It is a specialty, not the whole story.

Skills

What I work with

Grouped by how I actually use them — no percentages, no inflated levels.

Mobile Development

10 skills

Flutter
Dart
Kotlin
Riverpod
GetX State Management
BLoC Pattern
Nearby Connections (P2P)
Android & iOS Dev
Clean Architecture
Responsive Design

AI-Assisted Engineering

16 skills

Agentic AI Workflows
AI Agents in Flutter
On-device AI (ONNX Runtime)
Prompt Engineering
LLM Function & Tool Calling
Model Context Protocol (MCP)
Multi-Agent Systems
AI Diagnostics & Code Review
Cursor IDE
GitHub Copilot
Claude 3.5 Sonnet
GPT-4o / OpenAI
Gemini Pro
OpenRouter APIs
Local LLM Deployment (Ollama)
Local Llama models

Backend & APIs

15 skills

Firebase Auth
Cloud Firestore
Cloud Functions
Firebase Cloud Messaging
Firebase Storage
Firebase Hosting
Node.js
TypeScript
Express.js
RESTful APIs
Supabase Backend
User Authentication (JWT)
WebSockets
Push Notifications
Python (desktop tooling)

Databases & Cache

5 skills

PostgreSQL
MongoDB
SQLite Local
Hive Database
Shared Preferences

DevOps & Deployment

6 skills

Git / Version Control
GitHub Actions
CI/CD Pipelines
Play Store Console
App Store Connect
Vercel Deployment

Travel Technology (OTA)

6 skills

Flight Booking Systems
Hotel Booking Systems
Transfer Modules
Insurance Modules
eSIM API Integration
B2B & B2C Platforms

AI engineering

Expert in AI-assisted engineering

AI is how I ship faster — for coding, integration, and review. Tools listed are those named in my source portfolio.

AI-assisted development

My daily expert workflow: write, debug, refactor, and review code faster with AI — with human review before shipping.

Cursor IDE
GitHub Copilot
AI-assisted coding, debugging & refactoring
AI-assisted code review
Documentation generation

AI integration & APIs

Patterns I use in Flutter and backend services: agents, tools, and models wired into real features.

LLM API integration (OpenRouter, OpenAI, Gemini, Claude)
Prompt engineering
LLM function & tool calling
Model Context Protocol (MCP)
Local LLM deployment — Ollama / Local Llama
Agentic workflows & tool orchestration

Engineering workflows

AI across the delivery loop — requirements, implementation, testing, and maintenance.

AI-assisted test generation
Debugging & root-cause analysis
AI diagnostics & code review
Development workflow automation
Reusable components & clean architecture

Shipped: TypeFix AI — a privacy-first, fully offline writing assistant for Android (Kotlin + Flutter) running ONNX Runtime Mobile on-device, with zero cloud calls.

Tools and workflows I use daily — listed items are those from my source portfolio, not invented claims.

Featured projects

Real work, real links

19 projects — from production apps and on-device AI to open-source work. Production travel apps link to their store listings; everything else links to GitHub. No invented metrics.

Showing 19 of 19 projects

Mobile

Production OTA app — Flutter, GetX, REST APIs

InnoTrip B2C

All-in-one B2C travel platform to discover, plan, and book flights, hotels, and custom packages with instant real-time checkout.

Real-time flight search, hotel reservations, and dynamic pricing filters
Secure multi-currency payments and automated booking confirmations
Network caching and responsive rendering for cross-platform performance

FlutterDartREST APIPayment GatewayOTA Systems

Play Store App Store

Mobile

Production OTA app

NoSafer Travel Agency

Premium B2C travel booking platform to discover, compare, and book flights, hotels, and holiday trips in a high-performance mobile app.

End-to-end flight booking and hotel search with modular structure
Travel insurance purchase and eSIM setup modules
Image loading, caching, and state-rebuild optimisation for smooth transitions

FlutterDartGetXREST APIOTA Systems

Play Store App Store

Mobile

Production OTA app

Travojet Mobile App

All-in-one travel agency app with visa support, holiday package planning, flight bookings, and hotel reservations, plus guidance and custom booking workflows.

Flight seat selection and booking flow state with GetX
Document scanner uploads and real-time status trackers for tourist visa applications
Push notifications and campaign banners

FlutterDartGetXREST APIPush Notification

Play Store App Store

AI spotlight — on-device AI

TypeFix AI

Privacy-first, fully offline AI writing assistant for Android — fixes your text in any app (WhatsApp, Chrome, Gmail, Notes) with on-device inference and zero cloud calls.

Native Android Kotlin typing engine (InputMethodService) paired with a Flutter management app — onboarding, model manager, preferences, privacy dashboard, local history
On-device ONNX Runtime Mobile inference, fully offline — no API calls, no cloud
DiffEngine + SafetyValidator block hallucinations and protect numbers, URLs, and emails

KotlinFlutterONNX RuntimeAndroid InputMethod

Code

Mobile

Mehndi Book (Offline & Online)

High-performance Android design app with curated mehndi/henna art collections, offline image caching, categorized galleries, and smooth interactive zooming.

Offline-first local image caching with preloading for zero-lag offline browsing
Responsive grid gallery with pinch-to-zoom and full-screen preview
Bitmap memory optimisation for continuous smooth scrolling

FlutterDartOffline CacheInteractive ViewerResponsive UI

Play Store

Mobile

GlassDrop

AirDrop-style nearby file sharing for Android — peer-to-peer over Wi-Fi and Bluetooth, with no internet, servers, or accounts required.

Built with Flutter + Google Nearby Connections (P2P_STAR) over Wi-Fi and Bluetooth
Consent-based pairing with a multi-file queue and live per-file progress
Received files save directly to Gallery/Downloads

FlutterDartNearby ConnectionsPeer-to-Peer

Code

Mobile

Disaster Alert App

Real-time disaster and flood alerts — live GDACS and OpenWeatherMap data, interactive maps, and SOS emergency messaging with location sharing.

Live disaster and flood alerts from GDACS + OpenWeatherMap APIs, with hashtag monitoring (#floodBD, #CycloneMocha)
Interactive OpenStreetMap with alert overlays, user location, and GPS-based alert filtering
SOS distress messaging with location sharing, push notifications, and Firebase email/password auth

FlutterDartFirebase AuthOpenStreetMapPush Notifications

Code

Mobile

OTA search UI

SkySearch

Flutter flight search UI — home, airport search, date picker, and passenger selection flows, documented with screenshots.

Home, airport search, date pick, and passenger select screens
Polished search UI flows captured in screenshots
Flight search experience built in Flutter

FlutterDartOTA Systems

Code

Mobile

Jomi Converter BD

Land measurement converter app for Bangladesh with simple, user-friendly UI.

Land-area conversions (Katha, Bigha, Decimal) using local formulas
Responsive clean grid layout for standard and tablet sizes
SQLite cache for recent conversions

FlutterDartSQLiteResponsive Grid

Code Play Store

Mobile

Library Management System

Full-featured Flutter app to manage books, users, and transactions. Flutter front-end + Supabase backend.

Flutter front-end linked to Supabase for real-time inventory updates
Secure auth flows (JWT) and role-based dashboard access
Hive local cache for offline book reads

FlutterDartSupabaseHive Database

Code

Mobile

Grocery App Using BLoC

Simple grocery app built with Flutter using BLoC for scalable, maintainable state management.

State flows structured with BLoC separation
Dynamic cart calculations and price aggregate animations
List-widget optimisation to avoid rebuilding off-screen items

FlutterDartBLoC PatternState Management

Code

Mobile

Fast Food App

Responsive Flutter food-ordering app to browse foods, manage cart, with smooth UI animations.

Hero-page custom transitions for food item cards
Dynamic list filter chips for food categories
Memory optimisation during heavy horizontal asset sliding

FlutterDartAnimationsUI Transitions

Code

Mobile

Weather App

Weather app fetching real-time data from OpenWeatherMap API. Includes dark mode and smooth animations.

OpenWeatherMap JSON endpoints via secure HTTP
Responsive state updates handling loading, empty, and offline errors
Weather-matching visuals and custom indicators

FlutterDartREST APIWeather Lottie

Code

Mobile

আবহাওয়া Pal (Weather Pal)

Bilingual weather app (Bangla & English) for Bangla-speaking users. Shows real-time forecasts and weather details.

Flutter localization (English/Bangla strings) dynamically
Regional meteorological databases for local predictions
UI grids adapting to Bengali script typography

FlutterDartLocalizationBilingual

Code

Package

Package author

date_with_range_picker

Customizable Flutter package for selecting a single date or a date range with a premium UI.

Smooth grid-calendar rendering with custom range-selection logic
Gesture-detection optimisation to reduce unnecessary rebuilds
Open-source on pub.dev with modular code and clean API

FlutterDartPackageOpen Source

Code Pub.dev

Tools

Desktop tool

SnapText

Lightweight offline Windows screenshot utility with automatic OCR — select a region and the extracted text lands on your clipboard.

Global shortcut Ctrl+Shift+X — select a region, local Tesseract OCR extracts the text, copy text or image to clipboard
Multi-monitor and high-DPI support
100% offline — no cloud, no telemetry

PythonTesseract OCRWindows

Code

Web

Tea Stall Review Website

Modern tea stall review website built with React and Firebase. Users can browse, review, and rate local tea stalls.

Firebase Firestore for real-time ratings and reviews
Responsive grid layouts with TailwindCSS
Secure auth so authors can only edit their own reviews

ReactFirebaseFirestoreTailwindCSS

Code Live

Web

3D web experience

Wings of the World

Browser-based 3D flight simulator built with Three.js — real satellite imagery of any city, departing from Hazrat Shahjalal International Airport (VGHS), Dhaka.

Five selectable aircraft with distinct flight physics: F-22 Raptor, B737 airliner, Extra 330 acrobatic prop, SR-71 Blackbird, and Cessna 172
Real satellite imagery of any city, with flights departing from VGHS Dhaka
Immersive Web Audio API sound in a pure browser-based 3D experience

Three.jsWebGLJavaScriptHTML5CSS3Web Audio API

Code Live

Web

3D web experience

Cosmic Odyssey

Interactive 3D WebGL astronomy portal — a deep cosmic zoom from galaxy to solar system to planets and moons, built with Three.js.

3-tier deep cosmic zoom: Galaxy → Solar System → Planets & Moons
Sagittarius A* black hole simulator with gravitational-lensing visualization
Bilingual English + Bengali (বাংলা) interface

Three.jsWebGLJavaScript

Code

Experience

Where I have worked

Nov 2025 — PresentCurrent role

Associate Software Engineer

Innovate Solutions

Build and maintain production Flutter apps with GetX, including OTA booking flows.
Integrate REST APIs for flight, hotel, transfer, insurance, and eSIM booking.
Publish and maintain Android and iOS apps on Google Play Store and Apple App Store.
Ship with Firebase services and AI-assisted workflows — review, diagnostics, refactoring — with human review before release.
Improve performance, UI consistency, memory use, and code maintainability.
Integrate WebSocket streams for real-time statuses.

FlutterDartGetXREST APIFirebaseeSIM IntegrationOTA SystemsWebSocket

Aug 2025 — Oct 2025

Junior Flutter Developer

Eon System

Built cross-platform mobile apps with Flutter and Dart.
Worked with senior developers on premium, responsive UI components.
Integrated third-party payment gateway APIs and RESTful services.
Managed state with GetX.
Built 2 complete mobile app modules from scratch and optimized rendering lifecycles.

FlutterDartGetXREST APIGitPayment Integration

Workflow

How I approach development

Flutter + Firebase + AI, in a practical delivery loop.

01
Requirements & architecture
Clarify the flow, edge cases, and data model before writing UI. Choose state management and module boundaries that stay maintainable.
02
Reusable Flutter components
Build small, composable widgets and shared patterns so screens stay consistent and changes stay cheap.
03
Backend — Firebase + APIs
Wire Firebase (Auth, Firestore, Functions, Messaging) plus REST and WebSocket APIs, with clear error, loading, and offline states.
04
AI-assisted delivery
Use AI-assisted coding, review, and diagnostics to move faster — with human review before shipping.
05
Testing & debugging
Verify happy paths and failure paths, trace root causes, and keep fixes narrow and reviewable.
06
Performance & maintainability
Watch rendering, caching, memory, and consistency. Work in small, reviewable Git changes. Prefer simple, readable code.

Contact

Let’s build something reliable together

For recruiters, engineering teams, and collaborators — the fastest way to reach me is email.

Available for opportunities

I am interested in Flutter and full-stack roles where AI-assisted delivery, Firebase backends, performance, and clean architecture matter.

Email me View CV

No contact form here — email links open your mail app so messages actually reach me.

Fahim MontasirOpi

Production Flutter apps, built with AI, backed by Firebase

What I work with

Expert in AI-assisted engineering

AI-assisted development

AI integration & APIs

Engineering workflows

Real work, real links

Where I have worked

Associate Software Engineer

Junior Flutter Developer

How I approach development

Requirements & architecture

Reusable Flutter components

Backend — Firebase + APIs

AI-assisted delivery

Testing & debugging

Performance & maintainability

Let’s build something reliable together

Available for opportunities