Credit Card Checker (Luhn)
The Luhn test detects typos but says nothing about whether the card is valid or funded. All local – no transmission.
The Luhn algorithm
Credit card numbers (and many other ID numbers) contain a check digit based on the Luhn method. It helps detect transposed digits and typos. The checker also shows the detected card type from the leading digits.
- Luhn check: Every second digit is doubled (digit sum if > 9), everything is summed – the total must be divisible by 10.
- Card type: Detection of Visa, Mastercard, American Express, Discover and Diners Club.
- Important: The test only checks the check digit, not the actual validity of the card.