Credit Card Generator - Complete Guide

Credit card generator creates test card numbers that pass Luhn validation. Generate numbers matching Visa, Mastercard, Amex, and other card formats. For software testing, form validation, and development only - not for fraud.

How It Works

Apply card network prefix (Visa: 4, MC: 51-55, Amex: 34/37), generate random middle digits to reach required length minus one, calculate Luhn check digit, append to create valid number. Optionally generate expiry and CVV.

Technical Details

Card formats: Visa (4xxx, 16 digits), Mastercard (51-55xx or 2221-2720, 16 digits), Amex (34xx/37xx, 15 digits), Discover (6011/65, 16 digits). All use Luhn checksum. CVV: 3 digits (4 for Amex). Expiry: MM/YY.

Common Use Cases

1. Payment Testing: Test payment forms without real cards.
2. Form Validation: Verify card input validation logic.
3. UI Development: Create realistic payment UI mockups.
4. API Testing: Test payment gateway integrations.

Code Examples

Credit Card Generator

const CARD_TYPES = {
  visa: { prefix: ['4'], length: 16, cvvLength: 3 },
  mastercard: { prefix: ['51', '52', '53', '54', '55'], length: 16, cvvLength: 3 },
  amex: { prefix: ['34', '37'], length: 15, cvvLength: 4 },
  discover: { prefix: ['6011', '65'], length: 16, cvvLength: 3 }
};

// Luhn check digit
function luhnCheckDigit(number) {
  const digits = String(number).split('').map(Number);
  digits.push(0);

  let sum = 0;
  for (let i = digits.length - 1; i >= 0; i--) {
    let digit = digits[i];
    if ((digits.length - i) % 2 === 0) {
      digit *= 2;
      if (digit > 9) digit -= 9;
    }
    sum += digit;
  }

  return (10 - (sum % 10)) % 10;
}

// Generate card number
function generateCardNumber(type = 'visa') {
  const config = CARD_TYPES[type];
  if (!config) throw new Error('Invalid card type');

  // Random prefix from type's prefixes
  const prefix = config.prefix[Math.floor(Math.random() * config.prefix.length)];

  // Generate random digits to fill
  let number = prefix;
  while (number.length < config.length - 1) {
    number += Math.floor(Math.random() * 10);
  }

  // Add check digit
  number += luhnCheckDigit(number);

  return number;
}

// Generate CVV
function generateCVV(type = 'visa') {
  const length = CARD_TYPES[type]?.cvvLength || 3;
  return Array(length).fill(0).map(() => Math.floor(Math.random() * 10)).join('');
}

// Generate expiry (future date)
function generateExpiry() {
  const now = new Date();
  const month = String(Math.floor(Math.random() * 12) + 1).padStart(2, '0');
  const year = String(now.getFullYear() + Math.floor(Math.random() * 5) + 1).slice(-2);
  return `${month}/${year}`;
}

// Generate complete test card
function generateTestCard(type = 'visa') {
  return {
    number: generateCardNumber(type).replace(/(\d{4})/g, '$1 ').trim(),
    cvv: generateCVV(type),
    expiry: generateExpiry(),
    type: type.toUpperCase()
  };
}

// Examples
console.log(generateTestCard('visa'));
// { number: "4532 1234 5678 9012", cvv: "123", expiry: "06/27", type: "VISA" }

console.log(generateTestCard('amex'));
// { number: "3712 345678 90123", cvv: "1234", expiry: "09/28", type: "AMEX" }

Generates test card numbers with proper formats, Luhn validation, CVV, and expiry dates.

Tips & Best Practices

• Use payment processor test cards for integration tests
• Generated cards are for form validation only
• Include multiple card types in tests
• Format with spaces for better UX testing
• Test edge cases (expired, wrong CVV length)

Common Mistakes to Avoid

• Attempting to use for real transactions (illegal)
• Not using official processor test cards
• Wrong length for card type
• Missing Luhn validation in generator
• Generating expired dates for testing

When to Use This Tool

Use for testing payment forms, UI development, and validation logic. Always use official test cards from payment processors for integration testing.

Frequently Asked Questions

Can I use generated cards for purchases?

No. Generated numbers pass Luhn but are not connected to real accounts. Using them for purchases is fraud and illegal. Use payment processor test cards.

What are official test card numbers?

Stripe: 4242424242424242. PayPal sandbox has test accounts. Each processor provides specific test numbers. These trigger test responses, not real charges.

Why generate if processors provide test cards?

For offline testing, unit tests, form validation before API calls, or generating variety of card types. Official test cards are better for integration testing.

Should I generate CVV and expiry?

For form testing, yes. CVV: random 3-4 digits. Expiry: future date. Real validation happens server-side with payment processor anyway.

Get Started

Ready to try Credit Card Generator? Use the tool now - it's free, fast, and works right in your browser.

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Last updated: June 27, 2026