Credit Card / Luhn Validator

Validate any credit card number with the Luhn (mod-10) checksum, detect the issuing brand (Visa, Mastercard, Amex, Discover, Diners, JCB, UnionPay), and check format. Browser-only — your card number is not transmitted.

How to use the Credit Card / Luhn Validator

Type or paste a card number; spaces and dashes are stripped. Validation runs as you type. Don't use this with a real production card on shared computers. For testing, use known test numbers (Stripe publishes a full list).

About the Luhn algorithm

The Luhn algorithm is a simple checksum that catches most single-digit errors and transpositions. It's used by every major card brand, plus IMEI numbers, Canadian SIN, US NPI, and others. It's not a fraud check — knowing the algorithm doesn't validate that a card exists or is funded. It only confirms the digits could be a real number.