Donaldson R F Credit Card Number Validator
Check that a card number is well-formed using the Luhn checksum, and see which card network it belongs to.
Your number never leaves this page. The check runs 100% in your browser: the number is not sent anywhere, not saved, not logged, and not put in the page address. Only the card number is needed — never enter an expiry date, CVV or PIN. For testing, use test numbers such as 4242 4242 4242 4242 instead of a real card.
–Luhn checksum
–Card type
–Digits
What the Luhn check does
Card numbers end in a check digit. Starting from the right, every second digit is doubled (subtracting 9 if the result is above 9), all digits are added up, and the total must be divisible by 10. This catches typos and most single-digit and transposition mistakes. It is a formatting check only: a number that passes may still not be a real or active account, and it says nothing about funds, expiry or ownership. The card type is guessed from the leading digits and the length. Nothing on this page contacts a bank or a card network.