Credit Card Validator
Check a card number with the Luhn algorithm and detect its network.
Checked with the Luhn algorithm in your browser. Never enter a real card you use — this is for test/format validation.
| Valid (Luhn) | — |
|---|---|
| Card network | — |
| Digits | — |
| Formatted | — |
Frequently asked questions
What is the Luhn algorithm?
The Luhn algorithm is a simple checksum formula used to catch accidental errors in numbers like credit cards. It doubles alternate digits, sums the results, and checks that the total is divisible by 10.
Does this tool check if a card is real or has money?
No. It only validates the number format using the Luhn checksum and detects the likely network; it never contacts a bank, charges anything, or looks up an account. A number can pass the check yet not be an active card.
Is my card number sent anywhere?
No. The validation runs entirely in your browser, so the number you enter is never uploaded or stored. Nothing leaves your device.
How does it detect the card network?
It examines the leading digits and length, which follow known patterns for Visa, Mastercard, American Express, Discover and others. Those prefixes identify the issuing network.
Why does a made-up number sometimes pass validation?
The Luhn check only confirms the digits form a mathematically valid sequence, not that the card exists. Test numbers built to satisfy the checksum will pass even though they are not real cards.
What is this validator useful for?
It is handy for catching typos in a card number, testing payment form logic, and confirming a test card is well-formed. It is a format check, not a payment or authorisation tool.
Does a valid number mean the card is safe to use?
No. Passing the Luhn test says nothing about whether a card is legitimate, active or authorised, so it should never be treated as proof of a working card.