Credit Card Validator

Credit card validation uses the Luhn algorithm (also known as the mod 10 algorithm) to verify that a card number is mathematically valid. It checks the card number format and performs a checksum calculation to detect typing errors.

This validator supports all major credit card types including Visa, MasterCard, American Express, Discover, Diners Club, JCB, UnionPay, and Maestro. It automatically detects the card type based on the number pattern.

Yes, absolutely. All validation happens entirely in your browser using JavaScript. No credit card numbers are transmitted to our servers or stored anywhere. Your data remains completely private and secure.

The Luhn algorithm is a checksum formula used to validate credit card numbers. It was developed by Hans Peter Luhn and helps detect simple errors in typing or transmitting credit card numbers by performing mathematical calculations on the digits.

This tool only validates the mathematical correctness of the card number itself, not the expiration date or whether the card is active. It checks if the number follows proper credit card formatting rules.

If a real card number shows as invalid, double-check for typos. The validator checks mathematical validity only - it cannot verify if a card is active, has sufficient funds, or belongs to you.

Yes, this tool is perfect for developers testing credit card form validation. You can use test card numbers provided by payment processors like Stripe or PayPal to verify your implementation.

A credit card number is invalid if it doesn't match the expected length for its card type, contains non-numeric characters, doesn't start with the correct digits for its type, or fails the Luhn algorithm checksum.