Credit Card / Luhn Algorithm Validator
Check identification and card numbers against the Luhn checksum algorithm.
Runs entirely in your browser — your data is never uploaded to any server.
How it works
- Enter numberInput digits
- Calculate Mod 10Applies Luhn formula
- Read validityValid or invalid checksum
What this tool does
- Luhn algorithm validation
- Card brand identification
- Zero server transmit
Frequently Asked Questions
No. This is an offline mathematical checksum validator. It does not contact any bank or store data.
Privacy and security
Your input is processed by JavaScript running inside your browser. Nothing you paste is sent over the network, logged, or stored — which is what makes this safe to use with production data. If you want to check this yourself: open your browser’s developer tools, switch to the Network tab, and use the tool — you will see no request carrying your file or input leave the page.