Credit Card Validator
Check whether a card number is valid (Luhn), in your browser.
This checks the Luhn checksum and the number length for the detected card type. A pass does not mean the card exists or has funds — only that the number is well-formed.
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Frequently asked questions
No. The validator runs entirely in your browser using JavaScript. The number you type never leaves this page and is not sent to a server, logged, or stored.
The Luhn algorithm is a simple checksum that catches most single-digit typos and transposed digits. A number that passes is well-formed, but that does not mean the card is real, active, or has available funds — only the issuer can confirm that.
Card networks use known starting digits (the IIN or BIN prefix): Visa numbers start with 4, Mastercard with 51–55 or 2221–2720, American Express with 34 or 37, and so on. The tool matches the prefix and also checks that the digit count is valid for that network.
Yes — use the standard test numbers published by payment processors, such as 4111 1111 1111 1111 (Visa) or 5555 5555 5555 4444 (Mastercard). These pass the Luhn check but are not linked to any account.
Last updated 2026-06-23.