What is the Luhn algorithm?

The Luhn algorithm is a simple checksum formula used to validate card numbers. It does NOT verify that a card is active or has funds — it only checks that the number is structurally valid.

Is it safe to enter real card numbers here?

The tool runs entirely in your browser and sends nothing to any server. That said, it is best practice never to enter real card numbers into any third-party tool unless absolutely necessary.

Can I generate test card numbers?

Yes. Click 'Generate Test Numbers' to see Luhn-valid test numbers for Visa, Mastercard, Amex, Discover, and JCB. These numbers pass the Luhn check but are not connected to real accounts.

Why does my card show as 'Unknown'?

Some card number prefixes (IINs) are not in the built-in detection list, or the number is too short to determine the network. The Luhn result is still shown.

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Credit Card Validator

Validate card numbers with Luhn check and detect card network

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关于此工具

Paste or type a credit card number — with or without spaces or dashes — and this tool immediately validates it using the Luhn algorithm and identifies the card network (Visa, Mastercard, Amex, Discover, JCB, UnionPay, Diners Club, Maestro). It shows the standard formatted number, the expected CVV length, and the expiry format for the detected network. You can also generate valid Luhn-passing test card numbers for each network — useful for development and QA. No real card data is transmitted; everything runs in your browser.

使用方法

1 Type or paste a card number into the input field. Spaces and dashes are ignored automatically.
2 The tool shows the Luhn validity, detected network, formatted number, and CVV/expiry format.
3 Click 'Generate Test Numbers' to get sample Luhn-valid numbers for major networks.
4 Use the copy button to copy any generated test number to your clipboard.

关于此工具

使用方法

常见问题