Free Credit Card Validator

Check a card number's Luhn checksum and brand.

This only checks the number format and Luhn checksum — it does not verify a real account. Use test card numbers, not real ones. Everything runs in your browser.

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What is the Credit Card Validator?

Before a payment ever leaves the browser, a card number can be sanity-checked with a bit of math — the Luhn algorithm catches most typos and transposed digits instantly. It's the same first-line check payment forms use to fail fast before hitting a gateway.

This credit card validator runs that Luhn check, verifies the length, and detects the card brand — using nothing but the number's format.

Last updated: Aug 13, 2026

What does this tool do?

You enter a card number and the tool strips spaces, runs the Luhn checksum, and checks the length against the detected brand's rules.

It reports whether the number is well-formed, which brand it matches (Visa, Mastercard, Amex and others), and whether the length is expected.

Key features

Luhn check

Validates the checksum digit.

Brand detection

Visa, Mastercard, Amex, Discover and more.

Length check

Verifies the digit count for the brand.

Format-only

No network calls, no real-account check.

Private

Runs entirely in your browser.

Example

Input

4242 4242 4242 4242

Processing

The tool runs the Luhn check and detects the brand.

Output

Valid — Visa, Luhn passes, 16 digits.

Common use cases

Developers — Test payment forms with valid-format numbers.
QA engineers — Verify validation logic behaves correctly.
Fintech builders — Prototype card input handling.
Students — Learn how the Luhn algorithm works.
Form designers — Understand client-side card checks.
Support teams — Confirm a test number is well-formed.
Educators — Demonstrate checksum validation.
Anyone testing checkout — Use valid test numbers safely.

Benefits

It catches typos before a payment is attempted.
It identifies the card brand from the number.
It confirms the length matches the brand.
It runs locally with nothing stored.

Tips

Use official test card numbers from your payment provider.
Never enter real card numbers into any online tool.
The Luhn check catches typos, not whether a card is real or funded.
Combine client-side checks with server-side gateway validation.
Brand detection uses number prefixes (BIN ranges).
Amex numbers are 15 digits; most others are 16.
Strip spaces and dashes before validating in code.
Always validate again on the server, never trust the client alone.

Common mistakes to avoid

Entering a real card number

Fix: Use your payment provider's published test numbers instead.

Assuming Luhn means valid card

Fix: Luhn only checks the checksum; it can't confirm a real, funded account.

Skipping server validation

Fix: Client-side checks are a convenience — always validate with the gateway too.

Hard-coding a 16-digit assumption

Fix: Amex is 15 digits and others vary; check length per brand.

How it works

1
Enter a number
A card number (spaces are ignored).
2
Validate
It runs the Luhn check and detects the brand.
3
Review
See validity, brand and length checks.

Frequently asked questions

No. It only checks the number's format, Luhn checksum and brand pattern — it can't confirm a real, active card.

It runs entirely in your browser and stores nothing, but you should still use test card numbers rather than real ones.

No. It only checks the number's format, Luhn checksum and brand pattern — it can't confirm a real or active card.

A simple checksum formula that detects most single-digit errors and transpositions in card and other ID numbers.

Visa, Mastercard, American Express, Discover, Diners Club, JCB and Maestro, based on number prefixes.

It runs entirely in your browser and stores nothing, but you should still use test numbers rather than real cards.

Either the Luhn checksum doesn't pass or the length doesn't match the detected brand — often a typo.

No. Validation happens locally in your browser.

Conclusion

A credit card validator gives you an instant, private format check for card numbers using the Luhn algorithm. Pair it with your payment provider's test numbers to build and verify checkout flows.