Luhn Validator
Validate card numbers with the Luhn checksum, detect brands, and compute check digits.
Valid card number
Passes the Luhn checksum. Format looks like a real card number (still synthetic — for testing only).
Brand
Visa
Length
16 digits
Masked
••••••••••••1111
What is the Luhn Validator?
The Luhn Validator checks whether a card number passes the Luhn checksum used by Visa, Mastercard, Amex, and other networks. It also detects the card brand and can compute the missing check digit for a partial number. Use it with our Credit Card Generator when you need to verify test numbers in checkout QA.
How to use it
Paste any card number in the Validate tab to see if it passes Luhn, which brand it matches, and why it fails if it does. In the Compute check digit tab, enter 11–18 digits to get a complete Luhn-valid test number you can copy into your fixtures.
Use cases
Checkout form QA: confirm test cards pass client-side Luhn validation before hitting the gateway. Payment fixture debugging: find which digit is wrong in a failing test number. Generating edge-case numbers: build valid numbers from any BIN prefix for parameterized tests. Support triage: quickly tell whether a reported card error is a typo or a gateway issue.
Does valid mean chargeable?
No. Luhn only proves the number is well-formed, not that an account exists or has funds. Only use test numbers from tools like our Credit Card Generator, and only against sandbox gateways. Never validate or store real card numbers in a browser tool.
