Validate a card number's format with the Luhn algorithm and identify the issuing network. Runs locally — no card data is transmitted or stored.
Credit Card Validator checks whether a card number is mathematically valid using the Luhn checksum algorithm and identifies the issuing network — Visa, Mastercard, American Express and others — based on the number's prefix and length. It is a developer and testing tool for confirming input validation logic, not a way to check whether a real card has funds or is currently active.
The entire check happens locally in your browser: the digits you type are run through the Luhn algorithm on-device, and nothing about the card number is transmitted anywhere or stored. This makes it safe to use with real card numbers for format-checking purposes, though the tool's real value is confirming that a number is structurally valid, which is only ever a first step before an actual payment processor performs the real authorisation.
The checksum calculation runs the moment you finish typing, immediately flagging a mistyped or fabricated card number.
Visa, Mastercard, American Express, Discover and other major networks are identified from the number's prefix and length pattern.
No card number is ever transmitted to a server, since the Luhn algorithm and network detection both run as simple client-side calculations.
Testing payment form validation logic is quicker with a tool that instantly confirms whether a test number passes the same checksum real payment systems check first.
No. This tool only validates the number's mathematical structure using the Luhn checksum and identifies the likely issuing network from its prefix; verifying balance, credit limit or whether the card is active requires contacting the issuing bank through an authorised payment processor.
Starting from the rightmost digit, every second digit is doubled, and if doubling produces a number greater than nine, its digits are summed. All digits are then added together, and the number is valid only if the total is a multiple of ten — a simple but effective way to catch typos and transposed digits.
Networks are identified by standardised prefixes: Visa numbers start with 4, Mastercard with 51-55 or 2221-2720, and American Express with 34 or 37, each with a defined expected length that the tool checks alongside the prefix.
Although the check is entirely local and nothing is transmitted, it is good practice to clear the field after testing and avoid leaving real card numbers visible on screen or saved in browser history through autofill.
No. It only validates the number's mathematical structure using the Luhn checksum and identifies the network. Balance and authorisation require the issuing bank.
Every second digit from the right is doubled (subtracting 9 if the result exceeds 9), all digits are summed, and a valid number gives a total divisible by 10.
Yes. Credit Card Validator on Klipza is completely free with no account, no subscription and no watermark on your files, and there is no daily usage limit.
Processing happens locally in your browser wherever technically possible, so your files are not uploaded to a server, stored or shared with third parties.
Yes. It is fully responsive and runs in any modern browser on Android, iPhone, iPad, Windows and macOS — nothing to install.