Credit Card Validator

Checks the digits agree, not that a card exists.

FREE - NO SIGN-UP - RUNS ON YOUR DEVICE

Nothing typed here is sent anywhere

  • Checksumand issuer
  • 8issuer ranges
  • Testnumbers only
  • 0uploads
Specification

Credit Card Validator at a glance

What is checked
The Luhn checksum
Input
Digits, spaces or dashes
Issuer
Named from opening digits
On a failure
Names the correct check digit
Not checked
Never whether a card is real
Price
Free
Account needed
None
Where processing happens
On your device
How to

How to use Credit Card Validator

  1. 1

    Use a test number

    Use a test number.

  2. 2

    Read the verdict

    Read the verdict.

  3. 3

    Find the typo

    Find the typo.

Questions

Frequently asked questions

Does this tell me a card is valid?

It tells you the digits are self-consistent. Whether a card exists, works or has money on it is known only to the bank that issued it.

Can I check my own card here?

There is no reason to type a real card number into a web page, including this one. Use the test numbers payment providers publish for testing.

What does the issuer name mean?

The opening digits and the length fall in published ranges, so the name is read from the number itself. Nothing is looked up anywhere.

Why did a real-looking number fail?

One digit is wrong, or two are swapped, which is exactly what the checksum was built to catch. The check digit that would have worked is named.

Background

What a card checksum can and cannot do

Validating a card number on a web page can only mean one thing: the checksum built into the digits adds up. Whether an account exists is known to the issuing bank alone.

  • The checksum catches a single mistyped digit and most swapped pairs.
  • It is a typing check, not a security check, and was never meant to be one.
  • The same formula is used on IMEI numbers and some national identifiers.
  • Test numbers are published by payment providers precisely so a real card is never needed.

Full specification

Specification of the Credit Card Validator tool
What is checkedThe Luhn checksum: every second digit doubled from the right, totalling a multiple of ten.
InputDigits with spaces or dashes. A published test number is loaded to begin with.
IssuerNamed from the opening digits and the length: Visa, Mastercard, Amex, Discover and others.
On a failureThe check digit that would have made it add up is named, which finds the typo.
Not checkedWhether the card exists, who holds it, or whether there is money on it.
PriceFree. Supported by clearly labelled ads outside the working area.
Account neededNo.
Where processing happensIn your browser tab. Nothing is uploaded.
Next step

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