🛡️ KAVACH - Smart UPI Payment App

Next-Generation UPI Payment App with AI-Powered Fraud Detection & Multi-Language Voice Assistant

Features • Tech Stack • Installation • Documentation • Architecture

📱 Overview

KAVACH is a comprehensive UPI payment application designed for the Indian market, featuring advanced security, multi-language support, and accessibility-first design. Built with cutting-edge fraud detection using Machine Learning and Natural Language Processing, KAVACH ensures safe and secure digital transactions for everyone.

🎯 Key Highlights

🤖 AI-Powered Fraud Detection - Real-time ML-based transaction and OTP fraud analysis
🗣️ Voice Assistant - Voice-powered UPI transactions in 22+ Indian languages
🔒 Advanced Security - Biometric authentication, behavioral analysis, SIM binding
💰 Complete Loan System - Apply, track, and manage loans with EMI calculator
📱 QR Payments - Scan and generate UPI QR codes instantly
🚫 Spam Detection - Identify fraudulent SMS and calls
🌍 Multi-Language - Support for 22 Indian regional languages
📴 Offline OTP - TOTP-based offline OTP generation
📊 Behavior Analytics - Real-time user behavior monitoring

✨ Features

🔐 Security & Fraud Protection

Feature	Description
ML Fraud Detection	Hugging Face BERT integration for OTP and transaction fraud analysis
Real-time Monitoring	SMS and transaction monitoring with risk scoring
Behavioral Biometrics	Touch patterns, typing speed, and cursor tracking analysis
Spam Detection	AI-powered SMS and call spam identification
SIM Binding	Auto-logout and data wipe on SIM card change
Screen Security	Screenshot and screen recording prevention

💳 Payment Features

Feature	Description
Voice Transactions	Voice-powered UPI payments with speech-to-text
QR Code Payments	Scan merchant QR codes or generate personal QR codes
Contact Picker	Send money to contacts directly
Transaction History	Complete payment history with fraud scores
Offline OTP	TOTP-based OTP generation without internet
Balance Check	Real-time balance inquiry

🏦 Loan Management

Feature	Description
Loan Application	Apply for Personal, Business, Education, Home, Vehicle loans
EMI Calculator	Real-time EMI calculation with amortization schedule
Loan Dashboard	Track all loans (Pending, Active, Completed)
EMI Payments	Pay EMIs with due date reminders
Early Payment	Calculate savings on early loan closure

🌐 Accessibility & Localization

Feature	Description
22+ Languages	Hindi, Bengali, Telugu, Tamil, Marathi, Gujarati, Kannada, Malayalam, Punjabi, Odia, Assamese, Urdu, and more
Voice Assistant	Hands-free operation for visually impaired users
Text-to-Speech	Screen reader support
Simple UI	Senior-citizen friendly interface
Educational Videos	UPI tutorial videos in regional languages

📊 Analytics & Monitoring

Feature	Description
Behavior Dashboard	Visualize typing patterns, cursor movements, gestures
Fraud Alerts	Real-time notifications for suspicious activities
Activity Logs	Complete audit trail of user actions
Security Dashboard	Centralized security status overview
SMS Fraud Dashboard	Monitor and manage SMS fraud detections

🏗️ Tech Stack

Frontend (Mobile App)

React Native 0.81.5 + Expo ~54.0.25

Category	Technologies
Framework	React Native, Expo
Navigation	@react-navigation/native, @react-navigation/native-stack
State Management	React Context API, React Hooks
UI Components	react-native-gesture-handler, react-native-safe-area-context
Internationalization	i18next, react-i18next
Authentication	expo-local-authentication (Fingerprint/Face ID)
Camera & QR	expo-camera, react-native-svg
Speech/Voice	expo-speech, @deepgram/sdk
Security	expo-screen-capture, expo-secure-store
Storage	@react-native-async-storage/async-storage

Backend (API Server)

Node.js + Express + MongoDB

Category	Technologies
Runtime	Node.js
Framework	Express 4.18.2
Database	MongoDB, Mongoose 8.0.3
Authentication	jsonwebtoken, bcryptjs
ML/NLP	Natural 6.10.2, Axios (Hugging Face API)
Security	OTPLib 12.0.1, express-validator
QR Codes	qrcode 1.5.3
File Upload	multer 1.4.5
CORS	cors 2.8.5

External Services

Service	Purpose
Hugging Face	ML-based fraud detection (BERT models)
Deepgram	Speech-to-Text for voice assistant
Cashfree	Payment gateway integration
MongoDB Atlas	Cloud database (production)

🚀 Installation

Prerequisites

Node.js (v18 or higher) - Download
MongoDB (v6.0 or higher) - Download
Git - Download
Expo CLI - Install via npm
Android Studio (for Android) or Xcode (for iOS)

Quick Start (Windows)

# Clone the repository
git clone https://github.com/Debjyoti-sarkar/KAVACH.git
cd KAVACH

# Run automated setup
.\quick-start.ps1

Manual Setup

1. Install Dependencies

# Install frontend dependencies
npm install

# Install backend dependencies
cd backend
npm install
cd ..

2. Configure Backend

Create backend/.env file:

# Server Configuration
PORT=5000
NODE_ENV=development

# Database
MONGO_URI=mongodb://localhost:27017/kavach

# Authentication
JWT_SECRET=your-super-secret-jwt-key-minimum-32-characters

# ML Services (Optional)
HUGGING_FACE_TOKEN=your_huggingface_token_here

3. Start MongoDB

Windows:

mongod --dbpath="C:\data\db"

macOS/Linux:

brew services start mongodb-community

4. Start Backend Server

cd backend
npm run dev

Verify at: http://localhost:5000

5. Configure Frontend API

Edit services/api.ts:

export const API_URL = __DEV__
  ? "http://localhost:5000/api"      // For emulator/simulator
  : "https://your-api.com/api";      // For production

For Android Emulator: Use http://10.0.2.2:5000/api

6. Start Expo App

npm start

Then:

Press i for iOS simulator
Press a for Android emulator
Scan QR code with Expo Go app for physical device

📖 Documentation

Document	Description
SETUP_GUIDE.md	Complete installation and deployment guide
FEATURES_README.md	Detailed feature documentation
MERGE_COMPLETE.md	Feature integration summary
backend/README.md	Backend API documentation
QUICKSTART.md	Quick start guide

🏛️ Architecture

System Architecture

┌─────────────────────────────────────────────────────┐
│                  Mobile App (Expo)                  │
│  ┌──────────┐  ┌──────────┐  ┌─────────────────┐  │
│  │ Screens  │  │ Services │  │ Context/Hooks   │  │
│  └────┬─────┘  └────┬─────┘  └────┬────────────┘  │
│       │             │              │                │
│       └─────────────┴──────────────┘                │
│                     ▼                               │
│            API Service (Axios)                      │
└────────────────────┬────────────────────────────────┘
                     │ HTTP/REST
                     ▼
┌─────────────────────────────────────────────────────┐
│              Backend (Express.js)                   │
│  ┌──────────┐  ┌──────────┐  ┌─────────────────┐  │
│  │  Routes  │→ │ Services │→ │    Models       │  │
│  └──────────┘  └──────────┘  └────┬────────────┘  │
│       ▲              ▲              │               │
│       │              └──────────────┼───────────┐   │
│       │                             ▼           │   │
│  Middleware                    MongoDB      ML API │
└─────────────────────────────────────────────────────┘

Project Structure

KAVACH/
├── 📱 Mobile App
│   ├── screens/              # All UI screens
│   ├── components/           # Reusable components
│   ├── navigation/           # Navigation configuration
│   ├── services/             # API & utility services
│   ├── hooks/                # Custom React hooks
│   ├── contexts/             # Context providers
│   ├── constants/            # Theme, i18n config
│   └── utils/                # Helper functions
│
├── 🔧 Backend
│   ├── models/               # 8 Mongoose models
│   ├── services/             # 8 Business logic services
│   ├── routes/               # 12 API route handlers
│   ├── middleware/           # Auth & validation
│   ├── config/               # Database configuration
│   └── server.js             # Express server entry
│
└── 📚 Documentation
    ├── SETUP_GUIDE.md
    ├── FEATURES_README.md
    └── MERGE_COMPLETE.md

🔌 API Endpoints

Authentication

POST /api/auth/register - Register new user
POST /api/auth/login - User login
GET /api/auth/me - Get current user
PUT /api/auth/change-pin - Change PIN

Transactions

POST /api/transactions/send - Send money (with fraud check)
GET /api/transactions - Get transaction history
GET /api/transactions/:id - Get transaction details

Fraud Detection

POST /api/ml/analyze-text - ML text analysis
POST /api/ml/analyze-otp - OTP fraud detection
GET /api/fraud-alerts - Get fraud alerts
POST /api/fraud-alerts - Create fraud alert

Loans

POST /api/loans/apply - Apply for loan
GET /api/loans - Get user loans
GET /api/loans/:id - Get loan details
GET /api/loans/:id/emis - Get loan EMI schedule

EMI

GET /api/emi - Get user EMIs
GET /api/emi/due - Get due EMIs
POST /api/emi/:id/pay - Pay EMI

QR Codes

POST /api/qr/generate - Generate UPI QR code
POST /api/qr/parse - Parse QR code

Spam Detection

POST /api/spam/analyze-message - Analyze SMS
POST /api/spam/analyze-phone - Check phone number
POST /api/spam/check-otp-legitimacy - Verify OTP message

Offline OTP

GET /api/offline-otp/generate - Generate TOTP
POST /api/offline-otp/verify - Verify TOTP

Full API documentation: backend/README.md

🧪 Testing

Backend Testing

cd backend

# Test health check
curl http://localhost:5000

# Test user registration
curl -X POST http://localhost:5000/api/auth/register \
  -H "Content-Type: application/json" \
  -d '{"phoneNumber":"9876543210","name":"Test User","pin":"123456"}'

Frontend Testing

# Clear cache and restart
npm start -- --clear

# Run on specific platform
npm run ios
npm run android

🔐 Security Features

✅ JWT Authentication - Secure token-based auth
✅ PIN Hashing - bcrypt password hashing
✅ Biometric Auth - Fingerprint/Face ID support
✅ Screen Security - Screenshot/recording prevention
✅ SIM Binding - Device security with SIM verification
✅ CORS Protection - Cross-origin request filtering
✅ Input Validation - express-validator for all inputs
✅ Activity Logging - Complete audit trail
✅ Fraud Scoring - ML-based risk assessment

🤝 Contributing

Contributions are welcome! Please follow these steps:

Fork the repository
Create a feature branch (git checkout -b feature/amazing-feature)
Commit your changes (git commit -m 'Add amazing feature')
Push to the branch (git push origin feature/amazing-feature)
Open a Pull Request

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

👥 Authors

Saket Raj - @Saket Raj

🙏 Acknowledgments

Hugging Face for ML models
Expo team for the amazing framework
MongoDB for database solutions
React Native community

📞 Support

For issues and questions:

📧 Email: support@kavach.app
🐛 Issues: GitHub Issues
📖 Docs: Documentation

Made with ❤️ for safer digital payments in India

⭐ Star this repository if you find it helpful!

📥 Download • 📖 Docs • 🐛 Report Bug

Name		Name	Last commit message	Last commit date
Latest commit History 7 Commits
.local/state/replit/agent		.local/state/replit/agent
KAVACH		KAVACH
assets		assets
attached_assets		attached_assets
backend		backend
components		components
constants		constants
context		context
contexts		contexts
data		data
hooks		hooks
navigation		navigation
plugins		plugins
screens		screens
scripts		scripts
server		server
services		services
utils		utils
web-dashboard		web-dashboard
.gitignore		.gitignore
.replit		.replit
App.tsx		App.tsx
BACKEND_INTEGRATION.md		BACKEND_INTEGRATION.md
BEHAVIOR_ANALYSIS_GUIDE.md		BEHAVIOR_ANALYSIS_GUIDE.md
DEPLOYMENT_GUIDE.md		DEPLOYMENT_GUIDE.md
FEATURES_README.md		FEATURES_README.md
INTEGRATION_MANIFEST.json		INTEGRATION_MANIFEST.json
MERGE_COMPLETE.md		MERGE_COMPLETE.md
MERGE_PLAN.md		MERGE_PLAN.md
PAYMENT_INTEGRATION.md		PAYMENT_INTEGRATION.md
QUICKSTART.md		QUICKSTART.md
README.md		README.md
SETUP_GUIDE.md		SETUP_GUIDE.md
app.json		app.json
babel.config.js		babel.config.js
build-web.ps1		build-web.ps1
design_guidelines.md		design_guidelines.md
eas.json		eas.json
eslint.config.js		eslint.config.js
index.js		index.js
install.log		install.log
metro.config.js		metro.config.js
package-lock.json		package-lock.json
package.json		package.json
quick-start.ps1		quick-start.ps1
tsconfig.json		tsconfig.json

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