Card Number Checksum (Luhn) Validator
Check whether a card number passes the Luhn checksum and identify the likely network, in your browser. No number is stored or sent.
Everything runs in your browser. No data is uploaded or stored.
About this tool
A free, no-signup tool: A validator that runs the Luhn checksum — the formula used to catch mistyped card numbers — and identifies the likely card network from the number's prefix.
Every major card number carries a check digit computed with the Luhn algorithm, so a single wrong or transposed digit fails the test. This is the same first-line check payment forms use before contacting a bank. The number is never stored or sent; the arithmetic happens locally.
It confirms a number is well-formed, not that it is a real, active, or authorised card.
How to use it
- Enter the card number (spaces and dashes are ignored).
- Read whether the Luhn checksum passes and the detected network.
- Use it to catch entry errors — never as evidence a card is genuine.
Frequently asked questions
Does passing Luhn mean the card is valid?
No. Luhn only proves the number is internally consistent. Whether a card exists, has funds, or is authorised is decided by the card network and issuer, never by a checksum.
Is it safe to type a card number here?
The check runs entirely in your browser and nothing is transmitted or saved. That said, avoid entering real card numbers into any site unnecessarily; a test number is enough to see how it works.
How is the network detected?
From the number's leading digits (the issuer identification range). It is a best-effort guess and does not cover every issuer.