Credit Card Validator

Paste a card number to run the Luhn check digit, see which network issued it and get it grouped for reading. Everything happens on your device — no number is ever uploaded.

This credit card validator runs the Luhn algorithm on the number you type and works out the card network — Visa, Mastercard, American Express, Discover, Diners Club or JCB — from its opening digits and length. It is a card number validator for developers and anyone filling in a form who wants to catch a mistyped digit early. The whole card number check happens in your browser with JavaScript, so nothing leaves your computer; still, use published test numbers rather than a real card you are worried about.

Card number to check

Spaces and dashes are fine. Only the digits are read.

This runs entirely in your browser. Nothing you type is sent anywhere, saved, or logged — the check happens on your device. Even so, this is built for developers testing with sample numbers. Don’t paste a real card you’re worried about.

Try a known test number:

Valid card number

Network

Visa

  • Recognised as Visa.
  • Length is right for Visa (16 digits).
  • Passes the Luhn check-digit test.
Formatted
4242 4242 4242 4242
Security code
3-digit CVV

A pass means the number is internally consistent (Luhn check digit and length). It does not confirm the card exists, is active, or has funds — only the issuing bank can tell you that.

How it works

  1. 1

    Type or paste the number

    Enter the card number with or without spaces and dashes. Only the digits are read, and they never leave your browser.

  2. 2

    Watch it check live

    As you type, the tool shows the detected network, whether the length fits and whether the Luhn check digit passes.

  3. 3

    Read the verdict

    A big valid or invalid badge tells you if the number is internally consistent, with the network and formatted grouping alongside.

Instant & 100% private — nothing is uploaded

Every calculation runs locally in your browser. The income, balances and goals you enter stay on your own device and are never sent to a server — nothing is stored, logged or shared.

Frequently asked questions

Is my card number sent anywhere?
No. The check runs entirely in your browser with JavaScript. The number is never uploaded, stored, logged or shared, and it disappears when you close the tab. Even so, this is aimed at developers using published test numbers, so avoid pasting a live card you are anxious about.
What does the Luhn check actually prove?
The Luhn algorithm is a checksum that catches most single-digit typos and simple transpositions. Passing it means the digits are internally consistent, not that the card is real, active or has money on it — only the issuing bank can confirm that.
How does it know the card network?
Card networks are assigned number ranges: Visa starts with 4, Mastercard with 51-55 or 2221-2720, American Express with 34 or 37, Discover with 6011, 65 or 644-649, and so on. The tool reads the leading digits and length to name the issuer.
Which test card numbers can I use?
Use the sample numbers from payment gateways such as 4242 4242 4242 4242 (Visa) or 5555 5555 5555 4444 (Mastercard). Tap a network button above to fill one in. These are designed for testing and are not tied to any real account.

Important

For information and planning only — not financial, tax or legal advice. These figures are estimates; rates, fees and rules vary, so confirm anything that affects a real decision with a qualified professional or the official source.

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