← Blogby Marcell Almeida

How to validate credit card numbers with Luhn

Paste a card or ID number — verify the Luhn check digit instantly.

The Luhn algorithm catches single-digit typos in card numbers and many identifier formats. The Luhn Checker runs mod-10 validation on pasted input — no card data sent anywhere.

Try it — paste number to validate

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How it works

  1. Paste number — digits only or with spaces/dashes.
  2. Luhn check — mod-10 checksum validated.
  3. Result — valid or invalid with explanation.

Not authorization

Luhn validation confirms format integrity only. It does not verify the card exists, has funds, or belongs to the payer.

IBAN validation

International bank accounts use mod-97 — see the IBAN Validator.

The How to validate credit card numbers with Luhn is free, runs locally, and never sends your data to a server. More developer tools at maratool.com.