Credit Card Validator
NewValidate a card number's Luhn checksum, detect its network (Visa, Mastercard, Amex, etc.), and generate fake test numbers for sandbox use.
All checks run locally in your browser. This tool validates checksum format only — it cannot tell you whether a card is active, funded, or real.
——————Frequently Asked Questions
Does this tool check whether a card is real or has funds?
No. It only verifies the Luhn checksum and the number's format/length against known network prefixes — the same math a payment form runs before ever contacting a card network. It cannot and does not check if a card exists, is active, or is authorized.
How does the Luhn algorithm actually work?
Starting from the rightmost digit, every second digit is doubled; if doubling produces a two-digit number, its digits are added together. All digits are then summed, and the number is valid if that sum is a multiple of 10.
Is it safe to paste a real card number into this tool?
The check runs entirely in your browser via JavaScript — nothing is sent to a server or logged. That said, we recommend using the built-in example/test numbers for anything other than verifying your own card entry logic.
What do the generated "test numbers" actually generate?
A random 16-digit number starting with the well-known Visa test prefix "4", with a correct Luhn check digit computed and appended. These are for exercising form validation and sandbox payment APIs only — they are not tied to any real account and will be rejected by any real payment processor.
Why does it say a valid-Luhn number could still be "not a real network"?
Luhn validity only proves the digits are internally consistent — the network detection is a separate step based on publicly documented BIN (bank identification number) prefix ranges for Visa, Mastercard, Amex, Discover, Diners Club, JCB, and UnionPay.