Credit Card Validator
Check whether a card number is correctly formatted using the Luhn checksum and detect its card brand. This is a format check only — it does not verify a real card, and nothing you type is uploaded or stored.
Enter the digits only — spaces and dashes are ignored. Never enter a CVV, expiry date or cardholder name here; this tool does not ask for them and does not need them.
Your result will appear here
Result
Format check only — this does not verify a real card, check whether a card is active, or confirm it belongs to anyone.
Test card (not a real card): 4242 4242 4242 4242 — the Stripe test card, shown here so you can try the checker safely. Never type a real card number into any website you do not trust.
How to use
- Type or paste a card number into the box — or click Use test card to try the Stripe test card 4242 4242 4242 4242.
- Click Validate card number to run the Luhn checksum and detect the brand from the number's prefix.
- Read the result: a valid format means the digits pass the checksum, not that the card is real or active.
Frequently asked questions
What is the Luhn check?
The Luhn algorithm is a simple checksum used on most payment card numbers. Starting from the rightmost digit, every second digit is doubled (subtracting 9 if the result is over 9), and all the digits are added up. If the total is divisible by 10, the number is correctly formatted. It catches typos, not fraud.
Does a valid result mean the card is real?
No. A valid Luhn result only means the digits are in a plausible format. It does not check whether the card exists, is active, has funds, or belongs to anyone. Only the card issuer can verify a real card.
How is the brand detected?
By the number's starting digits: Visa starts with 4, Mastercard with 51–55 or 2221–2720, American Express with 34 or 37, and Discover with 6011, 644–649 or 65. Other prefixes are shown as unknown.
Is my card number sent anywhere?
No. The check runs entirely in your browser with JavaScript. Nothing is uploaded, logged or stored by ToolNest, and you should still never enter a real card number into a tool you do not need to — use the test card above instead.