Do I need an API key?
No. The validation runs entirely in your browser. The signed verdict uses a throwaway demo key that the page requests from the live AffixIO API on its own.
Public tool
Is this card number valid?
Type any payment card number. Card Validator runs the Luhn algorithm that every valid card must satisfy, detects the card type from the number pattern, and checks the length, entirely in your browser, then asks the live AffixIO API for a signed yes or no.
- No API key
- No network call, runs in your browser
- Signed with ML-DSA-65
Card number to validate
Type or paste any card number. Spaces and dashes are ignored. The check is instant and runs entirely in your browser.
AffixIO proof
- Proof
- Answer
- Audit
- Policy
- Signed
- Algorithm
- Digest
- Signature
Stamped by the live AffixIO API and signed with ML-DSA-65, the FIPS 204 post-quantum algorithm. Nothing personal goes into the payload.
How to use it
Three moves, no sign-up.
Type a card number
Paste or type any payment card number. Spaces and dashes are ignored.
Press Validate
The tool runs the Luhn algorithm, detects the card type from the number pattern, and checks the length. It runs entirely in your browser.
Read the verdict
A YES means the number passes the Luhn check and matches a known card type and length. A NO tells you which check failed, with a signed proof from the live AffixIO API.
What you are looking at
The Luhn algorithm is the checksum that every valid payment card number must satisfy. It works by doubling every second digit from the right and checking that the total is a multiple of ten.
Card type detection reads the first few digits of the number to identify whether it is a Visa, Mastercard, American Express, Discover, JCB or another scheme, and checks the number against the correct length for that scheme.
The proof card shows the answer stamped by the live AffixIO API: a proof id, an audit id, the policy version, and an ML-DSA-65 signature over the payload digest.
Questions
Does this charge the card or check the balance?
No. It only checks that the number is correctly formed. It does not contact any bank or payment network.
Which card types are detected?
Visa, Mastercard, American Express, Discover, JCB, Diners Club, UnionPay and Maestro, from the number pattern.
What does the proof card show?
The answer stamped by the live AffixIO API: a proof id, an audit id, the policy version, and an ML-DSA-65 signature over the payload digest.