Credit Card Test Number Generator
Generate Luhn-valid fake card numbers for testing payment forms — or check whether a number passes the Luhn checksum
Generate test numbers
Validate a Luhn checksum
About this tool
The ToolNinja Credit Card Test Number Generator produces Luhn-valid fake card numbers — correctly formatted for Visa, Mastercard, American Express, and Discover — for testing payment form validation, without using real card data. Every generated number passes the Luhn checksum (the same mod-10 algorithm real card networks use to catch typos) and matches each network's real prefix and length rules, so it'll pass any client-side format validation your form runs. It is not, however, a real, working card number — there's no issuing bank behind it, and no payment processor will ever actually charge it. For a true end-to-end payment flow test (an actual simulated charge), use your payment processor's own published test numbers (Stripe, PayPal, and others all maintain official test card lists for their sandbox environments). The Luhn validator mode works the other direction: paste any number and check whether it passes the checksum, useful for debugging why a form's client-side validation is rejecting (or wrongly accepting) a number. Everything runs 100% in your browser.
When to use it
- →Filling out a payment form's UI/UX during development without typing real card data
- →Testing that a credit card input field correctly validates the Luhn checksum and rejects malformed numbers
- →Debugging why a specific number fails client-side Luhn validation
- →Demoing a checkout flow's front-end without wiring up a real payment processor sandbox
Tips
- ◆These numbers are for front-end format/checksum testing only — they will never process a real charge, and no payment processor sandbox will accept them as valid test cards either.
- ◆Each payment processor (Stripe, PayPal, Braintree, etc.) publishes its own official test numbers for actually simulating a charge in their sandbox — use those for end-to-end payment flow testing.
- ◆The Luhn checksum only confirms a number is structurally well-formed — it says nothing about whether a card exists, is active, or has any funds.
Frequently asked questions
Will these numbers actually work on a real checkout page?
No. They pass the Luhn checksum and match real network prefix/length rules, so they'll pass client-side format validation, but there's no bank account behind them — any real payment processor will reject an actual charge attempt against one. They exist purely to test your form's validation logic, not to process payments.
Is it legal and safe to generate numbers like this?
Yes — these numbers follow the same publicly documented Luhn algorithm and network prefix ranges used throughout the payments industry for testing, the same category as the well-known test numbers payment processors themselves publish (e.g. Stripe's 4242 4242 4242 4242). They don't correspond to real accounts and can't be used to charge anyone.
What's the difference between this and Stripe's official test card numbers?
Stripe's (and other processors') official test numbers are specifically wired into their own sandbox systems to simulate particular outcomes — a successful charge, a decline, a specific error. This tool's numbers are structurally valid (correct Luhn checksum, correct network format) but aren't registered with any processor's sandbox, so use this for front-end validation testing and the processor's own test numbers for actually simulating a transaction.