Core Features

Authentication

• Secure PIN-based login system
• Access restricted until authentication succeeds

Transactions

• Deposit and withdraw money
• Real-time balance updates
• Prevents invalid transactions

Account Tracking

• Balance checking functionality
• Transaction history logging

Data Persistence

• Data stored using local text/JSON files
• Maintains state between sessions

System Architecture

The system is designed using a modular approach where each component is responsible for a specific part of the ATM workflow.

Authentication Module → verifies user PIN
Transaction Module   → handles deposit & withdrawal
Storage Module       → manages file-based persistence
Validation Layer     → prevents invalid inputs & errors

System Rules & Constraints

• Access is denied after incorrect PIN attempts
• Withdrawals cannot exceed available balance
• Negative or invalid inputs are rejected
• All transactions update stored data immediately

Example Terminal Output

Sample interaction from the command-line interface:

Welcome to Secure ATM System

1. Check Balance
2. Deposit
3. Withdraw
4. Exit

Select option: 2
Enter amount: 500

Deposit successful
New Balance: 1500

Technologies Used

• Language: Python
• Storage: Text / JSON files
• Interface: Command Line (CLI)
• Design: Object-Oriented Programming

Project Links

• 💻 GitHub Repository

Why This Project?

This project demonstrates how real-world ATM systems manage authentication, transactions, and persistent storage while ensuring stability through validation. It highlights structured programming, modular design, and safe state management.