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Tom Utilities

Luhn チェック検証

開発者ユーティリティ

Luhn アルゴリズムでカード番号を検証し、Visa、Mastercard、Amex などのブランドを判定します。

使い方

How the Luhn check works

Starting from the right, every second digit is doubled and its digits summed. If the total is divisible by ten the number passes. The tool also guesses the network from the leading digits.

  1. Type or paste the card number.
  2. The result and card type update as you type.
  3. Copy the normalised number if needed.

よくある質問

Does a passing number mean the card is real?

No. The Luhn check only catches typing mistakes and random numbers. It says nothing about whether the card exists or is active.

Is my card number safe?

Yes, the check happens in your browser and the number is never transmitted.