💰 Personal Expense Tracker

A modern, scalable, multicurrency personal expense tracker built with the MERN stack, featuring Redis caching, BullMQ queues, and a beautiful React + Tailwind UI. It lets users track expenses, analyze spending, manage budgets, convert currencies, and receive smart budget alerts — all optimized for performance and scalability.

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🧩 Features

• Transactions: Add/view/filter/paginate expenses
• Analytics: Pie chart visualization by time range
• Budget: Donut chart with over/under budget insights + FAQs
• Currency Converter: 200+ currencies with live rates
• Profile & Preferences: Update base currency, budget, notifications, reset cycle
• Responsive UI: Tailwind CSS only, fully mobile-ready

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🏗 Tech Stack

• Frontend: React (Vite) • Tailwind CSS • Recharts • Redux
• Backend: Node.js • Express.js • MongoDB (Mongoose)
• Performance: Redis (caching) • BullMQ (email queue)
• Other: Nodemailer • JWT Auth • Valkey monitoring

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🚀 Key Optimizations

⚡ 1. Performance (Redis Caching)

• Intelligent caching for totals per user/period
• Incremental updates on expense add
• Smart TTL + DB fallback ✅ 75% faster responses, 66% fewer DB queries

📬 2. Scalable Email System (BullMQ)

• Async queue-based email sending
• Rate limit: 10 emails/user/day
• Queue monitoring dashboard ✅ Non-blocking API performance

🔔 3. Smart Budget Alerts

• Multi-threshold alerts (50%, 100%, configurable)
• Tracks last alert threshold to prevent duplicates
• Responsive HTML email templates ✅ Timely, personalized notifications

🧠 4. Monitoring & Health

• /admin/queues dashboard
• Health check endpoints
• Cache statistics and retry management

Demo Video

expense-tracker_W4ZtzJ4m.mp4

⚙️ Setup & Installation

1️⃣ Clone Repo

git clone https://github.com/your-username/Expense-tracker.git
cd Expense-tracker

2️⃣ Environment Variables

Backend .env

PORT=5000
MONGODB_URL="mongodb+srv://<your-url>/expenseTracker"
JWT_SECRET="your_secret_key"
MAIL_HOST="smtp.yourprovider.com"
MAIL_USER="your_email"
MAIL_PASS="your_password"
FRONTEND_URL="http://localhost:5173"
VALKEY_URL="redis://localhost:6379"
ADMIN_EMAIL="your_admin_email"

Frontend .env

VITE_API_URL="http://localhost:5000/api/v1"

3️⃣ Install Dependencies

Run for both frontend and backend:

npm install

4️⃣ Start Development

npm run dev

• Frontend: http://localhost:5173
• Backend: http://localhost:5000

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📊 Monitoring

• Queue Dashboard: /admin/queues
• Health Checks: /api/v1/health
• Cache Stats: /api/v1/cache/status

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🧭 Future Scope

• Recurring expenses
• CSV import/export
• Auto-categorization rules
• Household budgets
• Detailed cashflow reports

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📜 License

This project is open for personal and educational use.