About the Card Validator
Every payment card number carries a check digit calculated with the Luhn algorithm, which catches most single-digit typos and transpositions before a request ever reaches a payment processor. This tool runs that check and identifies the issuing network from the number prefix.
How to use the Card Validator
- Enter the card number; spaces and dashes are ignored.
- See whether the Luhn checksum passes.
- Read the detected card network and expected length.
- Use the generated test numbers for development rather than a real card.
Frequently asked questions
Does passing Luhn mean the card is real?
No. It only means the digits are internally consistent. Whether the account exists, has funds, or is active can only be answered by the issuing bank.
How does the Luhn algorithm work?
Starting from the right, double every second digit, subtract 9 from any result above 9, sum everything including the untouched digits, and check that the total divides by 10.
Is it safe to enter a card number here?
The check runs entirely in your browser with no network request. Even so, use the published test numbers rather than a live card — good habit, and it is what the tool is for.
How is the card network identified?
From the leading digits: 4 for Visa, 51–55 and 2221–2720 for Mastercard, 34 and 37 for American Express, 6011 and 65 for Discover.