Open Audit - AI-Powered Expense Auditing System

You can try Open Audit on: https://open-audit-dusky.vercel.app/

An intelligent expense management platform that uses AI to extract data from receipts, detect fraud, calculate taxes, and provide actionable financial insights.

Quick Start

# Clone the repository
git clone https://github.com/<your-org>/OpenAudit.git
cd OpenAudit

# Install backend dependencies and start backend server
cd backend
npm install
npm run dev

# In a new terminal, install frontend dependencies and start frontend server
cd ../frontend/open_audit
npm install
npm run dev

The backend runs on http://localhost:5000 and the frontend runs on http://localhost:5173.

✨ Features

Receipt Management

• Upload receipts in PDF, JPEG, and PNG formats
• AI-powered extraction using Google Gemini API
• Automatic vendor, amount, date, and category extraction
• Duplicate receipt detection
• Fraud flagging system

Tax Calculation

• Old regime vs. new regime tax computation (Indian tax system)
• Support for deductions (80C investments, HRA, standard deductions)
• HRA exemption calculations
• Real-time tax savings comparison

User Management

• JWT-based authentication with bcrypt password hashing
• Role-based access control (user/admin roles)
• Secure profile management
• Protected routes and endpoints

Dashboard Analytics

• View all uploaded receipts with detailed breakdown
• Track total expenses
• Identify and manage flagged receipts
• Analytics on spending patterns

🛠 Tech Stack

Backend:

• Node.js + Express.js v5.2.1 (REST API)
• PostgreSQL (via Neon cloud database)
• Google Generative AI (Gemini 1.5-flash)
• Multer for file uploads and storage
• JWT (jsonwebtoken) for authentication
• bcrypt for password hashing

Frontend:

• React 19.2.4 with TypeScript
• React Router v7.14.0 for navigation
• Axios v1.15.0 for HTTP requests
• Tailwind CSS v3.4.1 for styling
• React Context API for state management

Prerequisites

• Node.js v18 or higher
• PostgreSQL database (Neon recommended for cloud)
• Google Gemini API key (get it from Google AI Studio)
• npm or yarn

Getting Started

1. Database Setup

First, create your PostgreSQL database:

# Using Neon (cloud)
# Create a project at https://neon.tech and copy the connection string

# Or using local PostgreSQL
createdb open_audit

Initialize the database schema:

cd app
psql <DATABASE_URL> -f database/schema.sql

2. Backend Setup

cd app/backend

# Install dependencies
npm install

# Create .env file
cat > .env << EOF
PORT=5000
DATABASE_URL=postgresql://user:password@host:port/database
GEMINI_API_KEY=your_gemini_api_key_here
JWT_SECRET=your_super_secret_jwt_key_here
EOF

# Start the development server
npm run dev

Create a .env file in backend/ with the values above before starting the server. DATABASE_URL should point to your PostgreSQL instance, GEMINI_API_KEY must be valid, and JWT_SECRET is used for auth token signing.

The backend will run on http://localhost:5000

3. Frontend Setup

cd app/frontend/open_audit

# Install dependencies
npm install

# Start the development server
npm run dev

The frontend will run on http://localhost:5173

Project Structure

app/
├── backend/
│   ├── config/
│   │   └── db.js                 # PostgreSQL connection pool
│   ├── controllers/
│   │   ├── receiptController.js  # Receipt upload & fetch handlers
│   │   ├── authController.js     # Auth handlers
│   │   └── taxController.js      # Tax calculation handlers
│   ├── middleware/
│   │   ├── authMiddleware.js     # JWT verification
│   │   └── upload.js             # Multer configuration
│   ├── models/
│   │   ├── user.js               # User model with bcrypt
│   │   ├── receipt.js            # Receipt data model
│   │   └── tax.js                # Tax calculation model
│   ├── routes/
│   │   ├── authRoutes.js         # /api/auth endpoints
│   │   ├── receiptRoutes.js      # /api/upload, /api/receipts
│   │   └── taxRoutes.js          # /api/tax endpoints
│   ├── services/
│   │   ├── geminiServices.js     # AI receipt extraction
│   │   ├── authService.js        # JWT token management
│   │   └── fraudDetection.js     # Fraud detection logic
│   ├── uploads/                  # Uploaded receipt files
│   ├── index.js                  # Express app setup
│   └── package.json
│
├── frontend/
│   └── open_audit/
│       ├── src/
│       │   ├── components/
│       │   │   ├── Navbar.tsx           # Navigation bar
│       │   │   └── ProtectedRoute.tsx   # Route protection wrapper
│       │   ├── contexts/
│       │   │   └── AuthContext.tsx      # Global auth state
│       │   ├── pages/
│       │   │   ├── LoginPage.tsx
│       │   │   ├── RegisterPage.tsx
│       │   │   ├── DashboardPage.tsx
│       │   │   ├── UploadPage.tsx
│       │   │   ├── AdminPage.tsx
│       │   │   └── TaxPage.tsx
│       │   ├── App.tsx                  # Main app component
│       │   ├── main.tsx                 # Entry point
│       │   ├── index.css
│       │   └── App.css
│       ├── vite.config.ts
│       ├── tsconfig.json
│       └── package.json
│
├── database/
│   └── schema.sql                # PostgreSQL schema
└── README.md

API Endpoints

Authentication

Method	Endpoint	Body	Description
POST	/api/auth/register	{name, email, password}	Register new user
POST	/api/auth/login	{email, password}	Login user, returns JWT
GET	/api/auth/profile	-	Get logged-in user profile (requires auth)

Receipts

Method	Endpoint	Body	Description
POST	/api/upload	multipart/form-data (receipt)	Upload receipt for processing (requires auth)
GET	/api/receipts	-	Get all user receipts (requires auth)

Tax Calculation

Method	Endpoint	Body	Description
POST	/api/tax/calculate	{annualIncome, investments, otherDeductions, rentPaid}	Calculate tax for both regimes (requires auth)
GET	/api/tax/history	-	Get tax calculation history (requires auth)

Authentication

All endpoints except /api/auth/register and /api/auth/login require JWT authentication:

Authorization: Bearer <jwt_token>

Receipt Upload

Supported formats:

• PDF (application/pdf)
• JPEG (image/jpeg)
• PNG (image/png)
• Maximum file size: 10MB

The system extracts:

• Vendor/Store name
• Total amount
• Purchase date
• Category (inferred)
• Item details
• Confidence score

Fraud Detection

The system flags receipts for:

• Unusually high amounts (> ₹10,000)
• Missing critical fields
• Duplicate transactions (same vendor + amount)
• Invalid or suspicious data patterns

Tax Calculation

Old Regime

• Basic deductions: 80C, HRA, standard deduction
• HRA exemption based on rent paid vs. basic salary
• Progressive tax slabs

New Regime

• Higher standard deduction (₹75,000)
• Simplified without 80C/HRA deductions
• Competitive tax rates

Development

Running Both Servers

Terminal 1 - Backend:

cd app/backend
npm run dev

Terminal 2 - Frontend:

cd app/frontend/open_audit
npm run dev

Key Files to Know

• Authentication: backend/services/authService.js, backend/middleware/authMiddleware.js
• Receipt Processing: backend/services/geminiServices.js, backend/controllers/receiptController.js
• Database Pool: backend/config/db.js
• Frontend State: frontend/src/contexts/AuthContext.tsx

Troubleshooting

Issue	Solution
Backend won't start	Check DATABASE_URL and ensure PostgreSQL is running
Port 5000 in use	Change PORT in .env or kill the process using the port
Receipt extraction fails	Verify GEMINI_API_KEY is valid; check file format/size
Database connection error	Verify connection string and network access to database
Frontend auth errors	Clear browser localStorage and .env JWT_SECRET
CORS errors	Backend must be running on http://localhost:5000

Deployment

Backend (Node.js)

• Deploy to Heroku, Railway, Render, or DigitalOcean
• Set environment variables on deployment platform
• Ensure PostgreSQL database is accessible

Frontend (React)

• Build: npm run build
• Deploy to Vercel, Netlify, or similar
• Update API URL to production backend

Sample Data

The system includes mock data generation for testing without Gemini API key configured.

Contributing

1. Fork the repository
2. Create a feature branch
3. Commit changes
4. Push to branch
5. Create Pull Request

Environment Variables Reference

# Backend
PORT=5000
DATABASE_URL=postgresql://user:password@host:port/database
GEMINI_API_KEY=your_gemini_api_key
JWT_SECRET=your_secret_key_min_32_chars

# Frontend (optional, if using .env)
VITE_API_URL=http://localhost:5000

Resources

• Google Gemini API Docs
• Express.js Documentation
• React Documentation
• PostgreSQL Documentation
• Tailwind CSS

License

MIT License - Feel free to use this project for learning and commercial purposes.

Team

Built during the FantomCode Hackathon 2026

---

**Happy Auditing! **

PORT=5000
DATABASE_URL=postgresql://username:password@localhost:5432/open_audit
GEMINI_API_KEY=your_api_key_here  # Optional

4. Start the server:

npm run dev

Frontend Setup

1. Navigate to frontend directory:

cd app/frontend/open_audit

2. Install dependencies:

npm install

3. Start the development server:

npm run dev

Usage

1. Open the frontend at http://localhost:5173
2. Upload a receipt image
3. View extracted data in the dashboard
4. Check for flagged receipts

API Endpoints

• POST /api/upload - Upload receipt
• GET /api/receipts - Get all receipts

Project Structure

app/
├── backend/
│   ├── controllers/
│   ├── models/
│   ├── routes/
│   ├── services/
│   └── index.js
├── frontend/open_audit/
│   ├── src/
│   │   ├── pages/
│   │   └── App.tsx
└── database/
    └── schema.sql