Test card numbers for development, not real purchases
Pick a card network and this tool generates random numbers that follow that network's prefix pattern and pass the Luhn checksum - the same format validation a real payment form would run. These numbers are not issued to any real account and will be declined by any real payment processor; they exist purely to test that your form's validation logic accepts correctly-formatted numbers. For actually testing a payment integration end-to-end, use your payment provider's own official test card numbers (such as Stripe's published test cards), which their sandbox is specifically built to recognize.
What the Luhn checksum actually verifies
The Luhn algorithm is a simple checksum formula built into every major card network's numbering scheme - it catches common typos and transcription errors (like a single mistyped digit or two adjacent digits swapped) before a number is even sent to a payment processor. A number passing Luhn means it's correctly formatted, not that it corresponds to a real, funded account - those are two entirely separate checks.
Why format validation and real payment testing are different needs
This tool is useful specifically for checking that your own form correctly accepts well-formatted numbers and correctly rejects malformed ones (wrong length, failed checksum) - a narrower, faster check than full payment integration testing, which needs your payment provider's actual sandbox environment and its own officially designated test numbers to simulate real transaction outcomes like declines and successful charges.
Why each network has a different number length and prefix
Visa, Mastercard, American Express, and Discover each reserve their own specific prefix ranges and total digit lengths as part of the international card numbering standard - which is exactly why a generator needs to know the selected network before producing a number, rather than generating generic digits that happen to pass Luhn.