MarketPlace App

A mobile marketplace app built with Flutter where users can buy, sell, and exchange items — similar to OLX or Facebook Marketplace.

Features

• Browse products in a grid layout with search and category filters
• View product details with seller info
• Post listings for sale or exchange
• Simulate secure payment with card details
• Make offers on listings
• In-app notifications with unread badge
• User login and registration
• Data stored in MongoDB

Tech Stack

Layer	Technology
Mobile App	Flutter (Dart)
Backend API	Node.js + Express
Database	MongoDB
Auth	JWT + bcrypt

Prerequisites

Make sure you have these installed before running the app:

• Flutter SDK 3.22+
• Dart 3.4+
• Node.js 18+
• MongoDB (local) or MongoDB Atlas
• Android Studio (for Android emulator)
• VS Code with Flutter & Dart extensions

Project Structure

marketplace_app/
├── lib/
│   ├── models/         # Product, NotificationItem
│   ├── data/           # Mock data
│   ├── screens/        # All app screens
│   ├── widgets/        # Reusable widgets
│   └── services/       # API and Auth services
└── backend/
    ├── models/         # Mongoose schemas
    ├── routes/         # API endpoints
    ├── server.js
    └── .env

Flutter Packages Used

Package	Purpose
http	API calls to backend
shared_preferences	Save login token locally
image_picker	Pick images from gallery
cupertino_icons	iOS style icons

Backend Packages Used

Package	Purpose
express	Web server framework
mongoose	MongoDB connection
bcryptjs	Password hashing
jsonwebtoken	User authentication
dotenv	Environment variables
cors	Allow Flutter to connect

Setup & Run

1. Backend

cd backend
npm install
node server.js

Make sure your .env file has:

PORT=5000
MONGODB_URI=mongodb://localhost:27017/marketplace
JWT_SECRET=your_secret_key

2. Flutter App

flutter pub get
flutter run

For Android emulator, change localhost to 10.0.2.2 in lib/services/api_service.dart

Screens

• HomeScreen — product grid with search and filters
• ProductDetailScreen — full product info with buy/offer buttons
• AddProductScreen — form to post a new listing
• PaymentScreen — simulated secure checkout
• NotificationScreen — list of alerts and offers
• LoginScreen — login and registration

Notes

• Payment is simulated (no real transactions)
• Notifications are mock/in-app only
• Images are loaded from picsum.photos