I Built a Fun Functional ATM in Python (And It Taught Me More Than I Expected 💳🐍)

Source: Dev.to

🏧 What Our Python ATM Can Do

• ✅ PIN authentication
• ✅ Balance checking
• ✅ Cash withdrawal
• ✅ Deposit money
• ✅ Clean menu‑driven flow
• ✅ Error handling (no negative withdrawals)

All in pure Python, no external libraries.

🎭 Think of an ATM Like a Gatekeeper

An ATM doesn’t care who you are; it only cares about rules:

• Correct PIN?
• Enough balance?
• Valid amount?

Our Python ATM follows the same logic.

🧠 Step 1: The Brain (Account Data)

account = {
    "pin": "1234",
    "balance": 5000
}

🔐 Step 2: PIN Authentication (The Bouncer)

def authenticate():
    pin = input("Enter your PIN: ")
    if pin == account["pin"]:
        print("✅ Access Granted\n")
        return True
    else:
        print("❌ Incorrect PIN")
        return False

No correct PIN = no party.

💰 Step 3: Check Balance

def check_balance():
    print(f"💳 Your current balance is: Rs {account['balance']}")

💸 Step 4: Withdraw Money (With Rules!)

def withdraw():
    amount = int(input("Enter amount to withdraw: "))
    if amount  account["balance"]:
        print("❌ Insufficient balance")
    else:
        account["balance"] -= amount
        print(f"✅ Withdrawal successful! New balance: Rs {account['balance']}")

No overdrafts. No drama.

💵 Step 5: Deposit Money

def deposit():
    amount = int(input("Enter amount to deposit: "))
    if amount <= 0:
        print("⚠️ Invalid amount")
    else:
        account["balance"] += amount
        print(f"✅ Deposit successful! New balance: Rs {account['balance']}")

Best feature—money goes in 😄

🧭 Step 6: The ATM Menu (Where the Magic Happens)

def atm_menu():
    while True:
        print("\n🏧 ATM MENU")
        print("1. Check Balance")
        print("2. Withdraw Money")
        print("3. Deposit Money")
        print("4. Exit")
        choice = input("Choose an option: ")

        if choice == "1":
            check_balance()
        elif choice == "2":
            withdraw()
        elif choice == "3":
            deposit()
        elif choice == "4":
            print("👋 Thank you for using the ATM")
            break
        else:
            print("⚠️ Invalid choice")

The loop keeps the ATM alive until the user walks away.

🚀 Step 7: Run the ATM

if authenticate():
    atm_menu()

That’s it—a working ATM built from logic, not magic.

🎯 What This Tiny ATM Teaches You

• Functions & modular design
• Input validation
• State management
• Security basics
• User‑experience logic

These are the same principles used in banking apps, payment systems, and backend services.

🧪 Want to Level It Up?

• Multiple users
• PIN retry limit
• Transaction history
• File‑based storage
• GUI or web interface

Each upgrade moves you closer to real‑world app development.

🧠 Final Thought

Building small, fun projects like this ATM isn’t “toy coding.” It’s how real developers learn to think. If you can build an ATM, you can build anything.

Happy coding 🐍💻