Credit Card Validator
Check if a card number is well-formed and which network it belongs to.
Use test numbers. This tool runs entirely in your browser and stores nothing, but there's no reason to type a real card number into any website you don't buy from. It only checks the format — not whether a card exists, is active or has funds.
Official test numbers
| Network | Test number |
|---|
● The number is checked in your browser only. It is never stored, logged or sent anywhere.
How it works
The Luhn algorithm (mod 10) detects typos: double every second digit from the right, subtract 9 from results above 9, and the total must be divisible by 10. The network is recognized from the first digits (the IIN): 4 for Visa, 51–55 and 2221–2720 for Mastercard, 34/37 for American Express, and so on. Developers can use the test numbers below with payment sandboxes such as Stripe.