# Credit Card Validator Check whether a card number passes the Luhn checksum and identify its brand — Visa, Mastercard, American Express, Discover and more. Useful for testing forms and validation logic. It only checks the number's structure; it does not verify that a real account exists. ### How it works Card numbers carry a built-in check digit governed by the **Luhn algorithm**: starting from the right, every second digit is doubled (subtracting 9 when the result exceeds 9), all digits are summed, and a valid number's total is divisible by 10. The tool runs that checksum and separately matches the number's length and leading digits (its IIN/BIN prefix) against known brand ranges to name the issuer. Everything is computed locally — no number is stored or sent anywhere, and this is for testing only. --- *Source: [ocxly.com/credit-card-validator.html](https://ocxly.com/credit-card-validator.html) — OCXLY, free 100% client-side privacy-first tools. Free credit card validator using the Luhn checksum with brand detection (Visa, Mastercard, Amex and more), entirely in your browser. For testing only.*