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Developer Essentials · Free Tool

Card Number Validator

Check whether a card number passes the Luhn checksum and identify its brand — all in your browser. This only validates the format; it says nothing about whether a card is real or active.

Brand
Digits
Luhn check

How it works

The Luhn algorithm is a checksum used by nearly all payment cards: doubling every second digit from the right (subtracting 9 if the result exceeds 9), summing everything, and checking the total is divisible by 10. It catches most typos. The brand is inferred from the leading digits and length (Visa 4…, Mastercard 51–55/2221–2720, Amex 34/37, and so on). A valid checksum does not mean the card exists or is active — it’s only a format check, computed entirely on your device.