Expense Tracker Application 💰

A secure, full-stack expense tracking application built with React, Node.js, Express, and MongoDB.

Features

✅ User Authentication

• Secure registration and login with bcrypt password hashing
• JWT token-based authentication
• Session management

✅ Expense Management

• Add, edit, and delete expenses
• Track expenses with amount, category, date, and notes
• Filter expenses by date range and category
• View expense list with sorting options

✅ Category Management

• Pre-defined categories (Food, Transportation, Entertainment, Healthcare, Shopping, Bills, Other)
• Add custom categories
• Delete categories
• Category-based expense filtering

✅ Reports & Analytics

• Daily expense reports with line charts
• Monthly expense reports with bar charts
• Yearly expense reports with visualizations
• Category breakdown with pie charts
• Total spending analysis

✅ Security

• AES encryption for sensitive data (expense notes)
• Secure password hashing with bcrypt (10 salt rounds)
• JWT token authentication
• HTTPS ready for production deployment
• MongoDB user isolation (each user can only see their own expenses)

Tech Stack

Frontend

• React 19 - UI library
• React Router v6 - Client-side routing
• Bootstrap 5 - UI framework
• Axios - HTTP client
• Chart.js - Data visualization
• React-ChartJS-2 - React wrapper for Chart.js
• Vite - Build tool

Backend

• Node.js - Runtime
• Express.js - Web framework
• MongoDB - NoSQL database
• Bcrypt - Password hashing
• JWT - Authentication tokens
• CryptoJS - AES encryption/decryption
• CORS - Cross-origin support
• dotenv - Environment configuration

Installation & Setup

Prerequisites

• Node.js (v14 or higher)
• MongoDB (local or cloud instance)
• npm or yarn

Backend Setup

1. Navigate to the backend directory:

cd backend

2. Install dependencies:

npm install

3. Configure environment variables (.env file):

MONGO_URI=mongodb://localhost:27017
DBNAME=expense_tracker
JWT_SECRET=your_super_secret_jwt_key_change_this_in_production
ENCRYPTION_KEY=your_encryption_key_change_this_in_production
PORT=8081

4. Start the server:

npm run dev

The API will be running on http://localhost:8081

Frontend Setup

1. Navigate to the frontend directory:

cd frontend

2. Install dependencies:

npm install

3. Start the development server:

npm run dev

The app will be running on http://localhost:5173

API Endpoints

Authentication

• POST /signup - Register new user
• POST /login - Login user
• GET /user - Get current user info (requires auth)

Categories

• GET /categories - Get all user categories (requires auth)
• POST /categories - Add new category (requires auth)
• DELETE /categories/:categoryName - Delete category (requires auth)

Expenses

• GET /expenses - Get all expenses with optional filters (requires auth)
• GET /expenses/:id - Get single expense (requires auth)
• POST /expenses - Create new expense (requires auth)
• PUT /expenses/:id - Update expense (requires auth)
• DELETE /expenses/:id - Delete expense (requires auth)

Reports

• GET /reports/summary - Get expense summary by category (requires auth)
• GET /reports/daily - Get daily expenses (requires auth)
• GET /reports/monthly?year=YYYY - Get monthly expenses (requires auth)
• GET /reports/yearly - Get yearly expenses (requires auth)

Database Schema

Users Collection

{
  _id: ObjectId,
  email: String,
  password: String (hashed),
  createdAt: Date,
  categories: [String]
}

Expenses Collection

{
  _id: ObjectId,
  userId: String (references user._id),
  amount: Number,
  category: String,
  date: Date,
  notes: String (encrypted),
  createdAt: Date
}

Security Features

1. Password Security

   • Passwords are hashed using bcrypt with 10 salt rounds
   • Never stored in plain text
   • Compared securely during login

2. Data Encryption

   • Expense notes are encrypted using AES encryption
   • Encryption key stored in environment variables
   • Decryption on retrieval from database

3. Authentication

   • JWT tokens used for session management
   • Tokens expire after 480 minutes (8 hours)
   • Bearer token format: Authorization: Bearer <token>

4. Data Privacy

   • Each user can only access their own data
   • User ID is verified from JWT token on all protected routes
   • MongoDB queries filtered by userId

5. CORS Security

   • CORS enabled for client-server communication
   • Ready for HTTPS deployment

Usage

1. Register: Create a new account with email and password
2. Login: Access your account with credentials
3. Add Expenses: Navigate to "Expenses" tab, click "Add New Expense"
4. Manage Categories: Add custom expense categories
5. View Reports: Check "Reports" for various spending analytics
6. Edit/Delete: Modify or remove expenses as needed

Environment Variables

MONGO_URI          - MongoDB connection string
DBNAME             - Database name
JWT_SECRET         - Secret key for JWT signing (change in production!)
ENCRYPTION_KEY     - Key for AES encryption (change in production!)
PORT               - Server port (default: 8081)

Production Deployment

1. Update Environment Variables: Change all secret keys in production
2. Enable HTTPS: Use SSL/TLS certificates
3. Database: Use MongoDB Atlas or managed MongoDB service
4. Frontend: Build and deploy to hosting service
5. Backend: Deploy to Node.js hosting (Heroku, AWS, DigitalOcean, etc.)

Common Issues & Solutions

MongoDB Connection Error

• Ensure MongoDB is running locally or connection string is correct
• Check MONGO_URI in .env file

CORS Errors

• Frontend and backend must be accessible from each other
• Check CORS configuration in backend/index.js

Token Expired

• Tokens expire after 480 minutes
• User needs to login again to get new token

Future Enhancements

• Two-factor authentication (2FA)
• Budget alerts and notifications
• Recurring expense templates
• Receipt image uploads
• Export reports to PDF
• Mobile app version
• Multi-currency support
• Expense sharing with others

License

This project is provided as-is for educational purposes.

Support

For issues or questions, please refer to the documentation or contact support.

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Stay financially secure! 🔒💰