Mindful Messenger

Chat App with Matrix Protocol & AI Chatbot

Frontend Mobile Engineer (Flutter) · Internship Project

Aug 2023 - Dec 2023

An AI-powered instant messaging app built with Flutter using Clean Architecture and BLoC state management. Features direct Matrix REST API integration without third-party SDKs for maximum protocol control, real-time personal and group chats, AI chatbot integration using Google Gemini REST API, and a custom push notification gateway powered by Node.js and Firebase Cloud Messaging (FCM).

Flutter

Dart

Clean Architecture

BLoC

Offline-First

Android

iOS

REST API

Matrix Protocol

Firebase Cloud Messaging (FCM)

Vendor & Client

PT Simbolik Impera Dunia

Vendor

Technology, Information and Media

Yogyakarta, Indonesia

Deep Dives

Covering technical aspects, such as architecture, design decisions, and implementation details.

What am I doing?

Architected an offline-first messaging MVP using Flutter, BLoC, GetIt, and Clean Architecture, storing local chat history with Hive for offline access.
Engineered 1-on-1 and Group Chat features using Matrix REST API, implementing an in-app offline queue to auto-deliver pending messages upon connection recovery.
Built rich messaging capabilities including message selection, multi-chat forwarding, dynamic presence (online/last seen), typing indicators, read receipts, and support for voice notes, images, videos, documents, and emojis.
Built a custom push notification gateway using Node.js and Firebase Cloud Messaging (FCM) to trigger background message alerts.
Integrated real-time AI Chatbot services over WebSockets, later migrating the client-side integration to Google Gemini REST API to ensure continuous service availability and high response reliability.

Project Overview

Mindful Messenger is an AI-enhanced instant messaging application designed to foster knowledge-sharing alongside standard communication. Built with Flutter, the app combines real-time chat infrastructure with an AI chatbot assistant to deliver a seamless, intelligent user experience.

The Challenge

Strict Architectural Control: Standard SDKs often limit customization for complex state synchronization and custom network protocols.
Complex Messaging Protocols: Implementing the Matrix protocol from scratch using raw REST APIs required precise handling of request flows, authentication, and chat synchronization.
Real-time AI Integration & Push Services: The app needed to handle persistent WebSocket connections for live AI chatbot responses alongside a reliable background push notification pipeline.

Technical Strategy & Architecture

Clean Architecture & BLoC: Separated core business logic, domain models, and data layers to ensure maintainability, scalability, and testability.
Custom Matrix REST API Client: Bypassed the default Matrix SDK to build a lightweight, direct HTTP client tailored specifically to the project's data needs, enhancing performance and architectural flexibility.
Real-Time Communication: Utilized WebSockets for responsive interaction with the company's proprietary AI service.
Notification Gateway: Designed and deployed a custom Node.js middleware server acting as a bridge between internal chat events and Firebase Cloud Messaging (FCM).

Key Features Delivered

Messaging & Sync: Personal and group chat creation, real-time message synchronization, and chat history management.
AI Knowledge Assistant: Interactive chatbot integration allowing users to query information directly within the messaging interface.
Polished UX: High-fidelity UI slicing from Figma with micro-interactions, responsive chat mechanics, and custom UI animations.
Multi-Platform Push Notifications: Reliable background event delivery via the Node.js/FCM gateway.

Impact & Key Takeaways

Delivered MVP Status: Fully met company functional criteria and shipped a production-ready messaging foundation.
Deep Protocol Mastery: Gained hands-on experience in low-level REST API integration, state management, and real-time socket connection cycles.