Payment Security

Credit Card Validator

Execute the Luhn algorithm, identify the brand, and generate fictitious cards for QA before integrating payment gateways or anti-fraud systems.

Why use it

  • • Reduce typing errors in checkouts.
  • • Generate valid cards for sandbox testing.
  • • Train chatbots and support teams with secure data.

Related tools

Combine com o Secure Password Generator e com a Compound Interest Calculator para planejar limites e parcelamentos.

Bandeira para gerar cartão de teste

How the Luhn algorithm protects the card ecosystem

Created by Hans Peter Luhn in the 1950s, the algorithm is used by card brands and acquirers to verify the integrity of card numbers before authorizing transactions. It prevents simple typing errors and reduces basic fraud attempts.

Despite being simple, it is a mandatory requirement in PCI-DSS certifications and should be the first layer of validation in any checkout, gateway, or financial application.

Prefix and length table by brand

BrandCommon prefixesLength
Visa4XXX13 or 16 digits
Mastercard51 to 55 or 2221 to 272016 digits
American Express34 or 3715 digits
Diners Club300-305, 36, 3814 digits
Discover6011, 6516 digits

Our generator adopts standard prefixes and calculates the final digit with Luhn, ensuring compatibility with acquirer sandbox environments.

Best practices for product and anti-fraud teams

  • Validate the card number before starting any tokenization or encryption.
  • Block suspicious BINs and maintain updated lists with acquiring partners.
  • Test recurring billing flows with fictitious cards to ensure automated retries.
  • Integrate validation with 3DS solutions, behavioral anti-fraud, and risk scores.

Frequently asked questions

Doubts about the Luhn algorithm, use in sandbox, and anti-fraud policies.

How does the Luhn algorithm validate a credit card?+

The algorithm goes through the card digits from right to left, doubling every second digit and subtracting 9 when the result is greater than 9. Everything is added up and, if the total is divisible by 10, the number is considered valid. All major brands follow this rule before authorizing transactions.

Which brands are supported in this validation?+

The tool automatically recognizes popular brands (Visa, Mastercard, American Express, Diners Club, and Discover) by analyzing prefixes and length. If the brand is not identified, the number will still go through the Luhn check to ensure integrity.

Can I use the generated cards in production?+

No. The generated cards are fictitious and are intended to facilitate testing in payment systems, gateways, and anti-fraud. In production, use only real customer cards or data provided by acquirers and brands.

Does this tool check limit, status, or expiration?+

No. The validation only covers numerical integrity. Information such as limit, expiration, balance, or blocking depends on the acquirer or card issuer and cannot be accessed without the customer's authorization.

How to integrate the Luhn algorithm into my checkout?+

Include the validation in the frontend to alert the user in real time and repeat the calculation in the backend before sending the data to the gateway. Combine with BIN checks and risk lists for a more robust anti-fraud policy.