Credit card validator
Check a card number's Luhn checksum and detect its network. Runs locally — nothing is sent anywhere. Use a test number like 4242 4242 4242 4242 to try it.
- Network
- —
- Luhn checksum
- —
- Length
- —
What this tool checks
It runs the Luhn checksum (the algorithm every card number must satisfy) and detects the card network from the number prefix and length — Visa, Mastercard, Amex, Discover, JCB, Diners and more. It does NOT check whether the card exists, has funds, or is active; only a payment processor can do that.
The Luhn algorithm
The Luhn (mod-10) algorithm is a simple checksum: double every second digit from the right, sum the digits, and a valid number's total is divisible by 10. It catches most single-digit typos and adjacent transpositions, which is why nearly all card numbers use it.
Card networks detected
- Visa — starts with 4, length 13/16/19.
- Mastercard — 51–55 or 2221–2720, length 16.
- American Express — 34 or 37, length 15.
- Discover, JCB, Diners Club, UnionPay and Maestro.
Validate cards via API
Doing this at signup or checkout? Keep card logic off the client — call the Oxide Data Validator /v1/validate/card endpoint for Luhn + network detection at the edge.
curl -X POST https://data-validator5.p.rapidapi.com/v1/validate/card \
-H "Content-Type: application/json" \
-H "X-RapidAPI-Key: YOUR_KEY" \
-H "X-RapidAPI-Host: data-validator5.p.rapidapi.com" \
-d '{"number":"4242424242424242"}'FAQ
What does this credit-card validator check?
It runs the Luhn checksum (the algorithm every card number must satisfy) and detects the card network from the number prefix and length — Visa, Mastercard, Amex, Discover, JCB, Diners and more. It does NOT check whether the card exists, has funds, or is active; only a payment processor can do that.
Is it safe to type a card number here?
The check runs entirely in your browser — nothing is sent anywhere or logged. That said, never paste a real card number into any website you don't fully trust. Use a test number (e.g. 4242 4242 4242 4242) when you just want to see the validator work.
What is the Luhn algorithm?
The Luhn (mod-10) algorithm is a simple checksum: double every second digit from the right, sum the digits, and a valid number's total is divisible by 10. It catches most single-digit typos and adjacent transpositions, which is why nearly all card numbers use it.
Can a number pass Luhn but still be fake?
Yes. Luhn only proves the number is well-formed, not that it maps to a real, active account. Test card numbers pass Luhn by design. Real authorization requires a payment processor.
Can I validate cards from an API?
Yes. The Oxide Data Validator /v1/validate/card endpoint runs Luhn plus network detection server-side, so you can validate at signup or checkout without shipping card logic to the client.