Luhn-valid fake card numbers for testing checkout forms. Visa, Mastercard, Amex, Discover. Never real.
These numbers pass the Luhn checksum so they work in test forms, but they are not real accounts and cannot be charged. Use them only for development and QA, never enter them on a live payment page.
No. They are randomly generated numbers that merely satisfy the Luhn checksum and use a brand's prefix, so test systems accept their format. No bank account exists behind them and they cannot be charged.
It is the checksum formula every real card number also satisfies. The validator at the bottom tells you whether any number you paste passes it, which catches typos.
To exercise payment forms, validation logic and checkout flows during development without using a real card.