TTULAKITO
Developer

Luhn Card Validator

Validate credit card numbers and IMEIs using the Luhn algorithm.

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Luhn validation

Digits: 16
Brand:  Visa
Valid:  ✓ Passes Luhn check

Frequently asked questions

What does the Luhn algorithm actually check?
Luhn is a checksum that catches single-digit typos and most adjacent transpositions by verifying the number's check digit. It does not prove a card or IMEI is active or belongs to anyone - only that the digits are internally consistent.
Why do test card numbers like 4242 4242 4242 4242 pass Luhn?
Payment processors publish those numbers as valid Luhn sequences specifically so developers can exercise checkout flows without using real cards. They pass Luhn but are rejected by the live payment network.
Does Luhn work for any number length?
Yes, the algorithm processes digits right to left and works for any length, which is why it covers card PANs of 13 to 19 digits as well as 15-digit IMEIs and some national ID schemes.