Test
Card.
Generate Luhn-valid card numbers for UI & test-suite use. Numbers are picked from each issuer's real BIN ranges (so brand detection works), then a check digit is appended. These cannot be charged — they're random within issued BINs and have no real account behind them.
How these are generated
For each card we pick a real issuer BIN (the first 4–6 digits — e.g. Chase Sapphire starts 4147 32, HDFC Bank's Visa start 4193 78), fill the rest with random digits to the brand's standard length, then compute a Luhn check digit. The result looks like a real card — but a random middle and a fake holder make it useless to a payment processor.
Use for: form validation, fraud-rule unit tests, design mockups, Storybook fixtures.
Don't: attempt to charge them, ship them in screenshots, or use them as anything resembling a security boundary.