Credit Card Validator (Luhn Check) - Free Online Tool

The Credit Card Validator uses the Luhn algorithm (also known as the "modulus 10" or "mod 10" algorithm) to perform a checksum validation on a credit card number. It's a simple error-detection formula used to validate a variety of identification numbers. This tool is NOT a payment gateway; it does not check if a card is active or has funds. It only checks if the number is mathematically plausible. This is extremely useful for developers testing e-commerce checkout forms or validating user input to prevent simple typos. Crucially, this validation is performed 100% client-side in your browser, meaning the card number you enter is never saved, stored, or transmitted.