Free Credit Card Validator — Check Card Numbers With Luhn

Check whether a card number passes the Luhn checksum and identify its brand — Visa, Mastercard, Amex, Discover, Diners Club, or JCB. Everything runs in your browser, and the tool is strictly for test numbers: never enter a real card number.

Free Credit Card Validator — Check Card Numbers With Luhn

Credit Card Validator — Check Card Numbers With the Luhn Algorithm

Enter a test card number to check the Luhn checksum and detect its brand — Visa, Mastercard, Amex, Discover, Diners Club, or JCB. Everything runs 100% in your browser: never enter a real card number.

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For testing only. Never enter a real card number.

This page only checks a number’s format — it cannot charge anything or verify a real account. Use the sample test numbers below, never your real credit or debit card.

Validate a card number

Spaces and dashes are stripped automatically, so you can paste numbers however they are formatted.

Try a test number:
100% private

Runs entirely in your browser. Any number you type is never uploaded to any server.

No signup

Use it instantly. No accounts, no email, no waiting.

Free forever

Unlimited checks with no limits, no watermarks, no locked features.

How to use the credit card validator

  1. 1
    Read the warning first

    This tool is for test numbers only — the kind developers use when building checkout pages. Never type a real credit or debit card number here or anywhere you do not fully trust.

  2. 2
    Enter a test number

    Type or paste a test card number. Spaces and dashes are stripped automatically, so any formatting works. Or tap one of the sample test numbers to try it instantly.

  3. 3
    Hit Validate

    The page runs the Luhn checksum and reads the first digits (the IIN) to identify the card brand — all in a fraction of a second.

  4. 4
    Read the verdict

    Green means the number passes the checksum and is well-formed for its brand. Red means it has a typo or is not a real number for that brand.

Features

Real Luhn checksum

The same mod-10 algorithm banks and payment networks use to catch typos in card numbers — doubled digits, summed, and checked against zero.

Six-brand IIN detection

Reads the issuer identification number ranges for Visa, Mastercard (including the 2221-2720 range), American Express, Discover, Diners Club, and JCB.

Clear valid / invalid verdict

No jargon — a plain-English result that explains exactly what a pass or a fail actually means.

Auto-formatted display

The number is shown grouped the way it appears on real cards — 4-6-5 for Amex, 4-6-4 for Diners Club, groups of four for the rest.

Sample test numbers built in

One tap loads a known-valid Visa, Mastercard, or Amex test number — or a deliberately invalid one to see what a failure looks like.

Fully client-side

No network calls at all. Whatever you type stays on your device and disappears the moment you close the tab.

Frequently asked questions

What is the Luhn algorithm?
It is a simple checksum formula invented in 1954 and used on almost every payment card in the world. Starting from the rightmost digit, every second digit is doubled; digits over 9 have 9 subtracted; everything is added up. If the total ends in zero, the number is well-formed. It catches single-digit typos and most transpositions.
Does "valid" mean the card is real and active?
No. A valid result only means the number is well-formed for its brand — the checksum passes and the length and prefix look right. It says nothing about whether the account exists, is active, or has funds. Only the card issuer can confirm that.
Can this page charge a card or check a balance?
No, and it never could. It only does math on the digits you type — there is no connection to any bank, payment network, or processor. No charge, hold, or balance check is possible from this page.
Does my number leave my browser?
No. There are no network requests at all — you can verify this by opening the page with your WiFi off. Everything you type stays in your device's memory and is gone when you close the tab.
Which card brands are detected?
Visa (starts with 4), Mastercard (51-55 and 2221-2720), American Express (34, 37), Discover (6011, 622126-622925, 644-649, 65), Diners Club (300-305, 36, 38), and JCB (3528-3589). Anything else is reported as Unknown.
Why should I never enter a real card number?
Because even though this page never sends data anywhere, typing real card details into random websites is how card theft happens. Use official test numbers from payment providers (like Stripe's or your gateway's docs) when testing checkouts — that is exactly what this tool is for.
What do the sample test numbers do?
They are well-known dummy numbers from payment testing documentation. The Visa, Mastercard, and Amex samples pass the checksum; the fourth sample is deliberately broken so you can see what an invalid result looks like.

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