Luhn / IBAN / card validator
Check checksums and IBANs
Nothing is stored or sent: the check happens entirely in your browser. Avoid entering a real sensitive number if you are not comfortable.
This tool bundles three integrity checks. Luhn tests a digit sequence with the Luhn algorithm and shows the expected check digit. IBAN normalizes the code, checks the expected length per country and the mod-97 checksum. Bank card combines Luhn with brand detection (Visa, Mastercard, Amex, Discover, Diners…) by prefix and length.
No data is stored or sent: everything is computed in your browser, with no real number pre-filled, no tracking and no ads. It validates format, it does not verify a real account or card.
FAQ
What is the Luhn algorithm for?
It is a checksum formula that catches typing errors in card numbers, IMEIs, etc. It validates the format, not whether the number exists.
How is the IBAN checked?
Spaces are stripped, the expected length is checked against the country code, then the first 4 characters are moved to the end, letters become numbers (A=10…Z=35) and the whole value modulo 97 must equal 1.
Is my card number stored or sent?
No, never. Validation happens entirely in your browser, no number is stored, transmitted or pre-filled. Still, avoid entering a real sensitive number.
Does a valid card number actually work?
No. This tool only confirms the format and checksum are consistent; it says nothing about the existence or balance of the associated account.