Credit Card Number Validator
Check whether a card number passes the Luhn checksum, and identify its network.
About this tool
Check whether a card number passes the Luhn checksum used by all major card networks, and identify which network issues numbers in that format. Nothing is sent anywhere — the check runs entirely in your browser.
Key Features
- Luhn algorithm checksum validation
- Identifies Visa, Mastercard, American Express, and Discover formats
- Runs entirely in your browser
- Accepts spaces or dashes in the input
How to Use
- Enter a card number.
- Click Check.
- See whether it passes the checksum and which network format it matches.
Benefits
- Test payment form validation during development
- Catch a typo in a manually entered card number
- Understand how card numbers are structured
Frequently Asked Questions
No. This only checks that the number is mathematically self-consistent using the Luhn checksum, the same formula card issuers use to catch typos and generate valid-looking numbers. It cannot tell you whether the card actually exists, is active, or has any funds — only a payment processor talking to the issuing bank can determine that.
Starting from the rightmost digit, every second digit is doubled; if doubling produces a number over 9, its digits are added together (or equivalently, 9 is subtracted). All digits are then summed, and the number is valid if that total is a multiple of 10. It is a simple checksum designed to catch common errors like a single mistyped digit or two adjacent digits swapped.
No. The check runs entirely in JavaScript in your browser. Nothing you enter here is transmitted, logged, or stored anywhere — though as a general rule, avoid entering real card numbers into unfamiliar web tools, and use test numbers like 4111 1111 1111 1111 when you just want to verify this kind of validator.