Meet the Credit Card Number Validator
Check whether a card number passes the real Luhn algorithm checksum used by Visa, Mastercard, Amex and others, identify the likely card network from its.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
4111 1111 1111 1111 -> passes the Luhn check and matches Visa's prefix pattern — this is itself a widely published, standard test number, not a real account.Open the Credit Card Number Validator
Illustration. Open the tool for the real thing.
What is the Credit Card Number Validator?
The Luhn algorithm is the checksum formula card networks (Visa, Mastercard, American Express, Discover and others) build into every card number, so that a single mistyped or transposed digit can be caught instantly without contacting a bank. Paste any card-shaped number and this tool runs the real Luhn calculation — doubling every second digit from the right, summing the digits, and checking the total is divisible by 10 — to tell you whether it's mathematically valid, and identifies the likely network from its starting digits and length.
It's important to be clear about what this checks and doesn't: passing the Luhn test only proves the number is mathematically well-formed the way a real card number would be — it says absolutely nothing about whether the card exists, is active, or belongs to anyone. This tool also generates properly Luhn-valid test numbers on demand, useful for developers testing checkout forms, since using a real card number for testing is unnecessary and risky.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Runs the actual mod-10 algorithm used by every major card network.
Detects the likely network (Visa, Mastercard, Amex, Discover, etc.) from prefix and length patterns.
Creates properly Luhn-valid fake numbers for safely testing payment forms.
Honest about only checking mathematical structure, never real-world validity.
AZRS tools are free to open and use.
It opens in your browser, so there is nothing to download.
Used for
Pick one to see how it fits.
Developers testing checkout or payment forms
Generate valid-format test numbers instead of risking a real card number in a test environment.
Try it freeQA engineers
Verify that a payment form's client-side validation correctly catches a genuinely invalid (non-Luhn-passing) number.
Try it freeStudents learning about checksum algorithms
See the real mod-10 Luhn calculation worked out on an actual example.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This utility | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
What does the Luhn algorithm actually check?
A simple checksum: doubling every second digit from the rightmost digit, summing all digits (subtracting 9 from any doubled result over 9), and checking the total is divisible by 10 — it exists purely to catch typos and transposition errors.
Does passing this check mean the card is real?
No. It only means the number is mathematically well-formed the way a real card number would be — actual validity, activation and funds can only be confirmed by the issuing bank.
Is it safe to use the generated test numbers?
Yes, in a test/sandbox payment environment designed to accept them — they follow the same widely published pattern used in standard developer test suites and will not work for a real purchase.
How does it identify the card network?
By matching the number's starting digits (IIN/BIN range) and total length against each major network's publicly documented prefix patterns.
Is my card number sent anywhere?
No, the checksum calculation happens entirely locally in your browser.
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