Credit Card Validator
Check a card number’s format: Luhn checksum and card brand, right in your browser.
Every payment card number carries a built-in typo detector: its last digit is a check digit computed with the Luhn algorithm, invented by IBM scientist Hans Peter Luhn in 1954. Run the algorithm over the number and a valid one always ends in a multiple of ten — which is how checkout forms instantly spot most mistyped digits without contacting any bank.
Format check only: this page cannot verify that a card exists or has funds. Your number is processed locally and never leaves your device.
How to use
- Type or paste the card number — spaces are removed automatically and results update as you type.
- Read the brand detected from the prefix, whether the digit count matches that brand, and the Luhn checksum verdict.
- A failed checksum means a typo (or a fake number). A passed checksum only means the format is consistent — not that the card is real or funded.
About this tool
The first digits (the issuer identification number) reveal the brand and issuing network: 4 for Visa, 51–55 and 2221–2720 for Mastercard, 34/37 for American Express, 62 for UnionPay and so on. This validator combines both checks — pattern and checksum — entirely in your browser.
Be clear about the boundary: format validation is arithmetic, not banking. It cannot check expiry dates, CVV codes, balances, or whether an account exists — only the card networks can do that, at the moment of an actual transaction. Developers use tools like this with published test numbers (for example Stripe’s 4242 4242 4242 4242) to exercise checkout forms safely.
Frequently asked questions
Can this tell me if a card is real or has money on it?
No — and be wary of any site claiming it can. That information lives only inside the card networks and banks. This tool verifies the number’s format (brand pattern + Luhn checksum), which is all that can be checked publicly.
Is it safe to type a real card number here?
The check runs locally in your browser and the number is never transmitted or stored. Even so, best practice is to validate with test numbers and keep real card numbers for actual checkout pages run by your bank or a payment provider.
Why does 4242 4242 4242 4242 pass if it is not a real card?
It is a test number published by payment providers, deliberately built with a valid brand prefix and a correct Luhn digit so developers can test forms. Passing the format check is exactly what it is designed to do.
What is the Luhn algorithm in one line?
Double every second digit (subtracting 9 from results over 9), add everything up — if the total is a multiple of ten, the number is consistent.
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