What is the Luhn algorithm?

It's a mod-10 checksum used by all the major card networks since the 1960s. Starting from the rightmost digit, you double every other digit; if a doubled digit is greater than 9, you sum its digits. Then you sum everything. If the final total is divisible by 10, the number passes the check. The algorithm reliably catches single-digit typos and most transposition errors, which is why it became standard. It was designed by Hans Peter Luhn at IBM.

Are valid card numbers from the validator real?

No. The validator only confirms structural validity — that the Luhn check passes and the BIN is recognized. It can't tell you whether a real card with that number actually exists; that requires a payment processor lookup. The standard test numbers like 4111111111111111 are publicly known, pass the Luhn check, and work only in sandbox environments. Don't try to use them as real payment.

What card types does it detect?

The major networks: Visa (numbers starting with 4), Mastercard (51-55 or 22-27), American Express (34 or 37), Discover (6011 or 65), Diners Club (300-305 or 36), and JCB (35). Length validation varies by network — Visa permits 13, 16, or 19 digits, Mastercard uses 16, Amex uses 15, Discover uses 16. Less common cards may not be recognized at all and will fail the type detection step.

Can the tool generate test card numbers?

Some validators include a generator that produces Luhn-valid numbers in valid BIN ranges, which is useful for QA work. The standard test cards are preferred when possible — 4111111111111111 for Visa, 5555555555554444 for Mastercard, 378282246310005 for Amex. Most payment gateways accept these specific numbers in test mode and reject anything else.

Is BIN lookup included?

Basic BIN matching identifies the network (Visa, Mastercard, and so on). More detailed BIN lookups — covering the issuing bank, the country, and the card category (debit, credit, or prepaid) — require a commercial BIN database. Some validators include partial information; others link to external lookups. The detailed data is useful for fraud detection, but it usually isn't free.

Should card numbers be stored?

Almost never. PCI DSS strictly limits card storage and being in scope is a serious compliance burden. The industry standard is tokenization through a payment processor — Stripe, Braintree, Adyen, and others all offer it. The card number itself never touches your servers; you store and reuse a token instead. The validator helps with input validation, not with the storage compliance question, which is a different problem.

Is my card number sent to a server?

No. Browser-only validators run the Luhn check and BIN match entirely in JavaScript, so card numbers stay local. You can verify it for yourself by opening the network tab in your browser's developer tools — there should be no requests fired during validation. For PCI compliance, the right pattern is to validate locally and submit the card only through your payment processor's secure form or SDK.

Credit Card Validator

Validate credit card numbers online using the Luhn algorithm. Free card validator that detects Visa, Mastercard, Amex, and more.

Data / JSON

Instant results

Credit Card Number

Unknown

Valid length (13-19 digits)

Passes Luhn check

Card type detected

This tool validates the format and checksum. It does not verify if the card exists or has funds.

How to Use Credit Card Validator

Enter the card number

Paste or type a credit card number. Spaces and dashes are ignored automatically. The tool processes the input as you type — no submit button needed.

View the validation result

The tool reports whether the number is valid or invalid, identifies the card type (Visa, Mastercard, Amex, and so on), and shows the Luhn checksum status alongside length validation.

Inspect the details

The BIN (first six digits) identifies the card network. Some validators also surface the issuing country, the bank that issued the card, and the category — debit, credit, or prepaid.

Use it in your dev workflow

Validate user input in checkout forms for real-time feedback, generate test numbers for QA work, or verify the integrity of card data in test environments before it hits a payment processor.

When to Use Credit Card Validator

Form input validation

Real-time validation in checkout flows catches typos before users even hit submit. The validator detects the card type from the BIN (the first six digits), runs the Luhn checksum, and confirms the length is right for that network. Immediate feedback noticeably improves UX and reduces the number of failed payments caused by entry errors.

Test data generation

Generate Luhn-valid card numbers for use in QA environments. Many sandbox payment gateways accept any Luhn-valid number, and the standard test cards — 4111111111111111 for Visa, 5555555555554444 for Mastercard, 378282246310005 for Amex — are publicly known. The tool can validate cards, generate test ones, or both.

Card type detection

Identify the card network from the BIN range. Visa numbers start with 4; Mastercard falls in 51 through 55 or 22 through 27; Amex starts with 34 or 37; Discover uses 6011 or 65. This is useful for routing transactions to the right gateway, displaying the correct logo, or applying network-specific business rules.

Educational use

Walk through how the Luhn algorithm catches typos via a doubled-digit checksum. The mod-10 check has been used by all the major card networks since the 1960s, and seeing it work step-by-step is genuinely useful for payments developers, fraud analysts, and CS students learning about checksums.

Credit Card Validator Examples

Valid Visa

Input

4111111111111111

Output

Valid card. Type detected as Visa. Length is 16 digits, Luhn check passes.

The standard Visa test number. The leading 4 marks it as Visa, the 16-digit length matches Visa's main format, and the Luhn checksum passes. Most payment gateways accept this number in their test environments.

Failed Luhn check

Input

4111111111111112

Output

Invalid. Type detected as Visa from the BIN, but the Luhn check fails.

A single-digit typo of the valid card above. The BIN still identifies it as Visa, but the checksum fails — exactly the kind of typo that real users make in card entry forms. A validator catches this before the form ever reaches the payment processor.

Amex 15-digit

Input

378282246310005

Output

Valid card. Type detected as American Express. Length is 15 digits.

Amex uses 15 digits rather than the 16 you see on most other networks. The tool handles different lengths per card type, which matters because the visual format on the physical card is different too — Amex groups the digits as 4-6-5 instead of 4-4-4-4.

Tips & Best Practices for Credit Card Validator

1.A Luhn check is not the same as a real card. The validator confirms the number is structurally valid — right length, plausible BIN, passing checksum. It does not confirm that the card exists, has funds available, or isn't expired or stolen. Real validation requires a payment processor.
2.Don't store full card numbers in your own systems. PCI DSS strictly limits card storage, and you almost certainly don't want to be in scope. Tokenize through a payment processor like Stripe or Braintree instead — the validator is for input checking, not storage.
3.Public test card numbers only work in sandbox environments. Don't try to use them in production payment flows; they'll be declined immediately and may flag your account for fraud review.
4.BIN lookups can also reveal the issuing bank, country, and card category (debit, credit, or prepaid). This is useful for fraud detection, but you'll need a commercial BIN database to get the full information rather than just the network identification.
5.International cards have edge cases. Some networks support variable lengths or have region-specific rules. The validator covers the major networks well; for less common cards, you may need a network-specific validator or a commercial validation service.
6.For PCI compliance, validate in the browser and never send raw card numbers to your own server. Submit the tokenized data through your payment processor's SDK so the card itself never crosses your infrastructure.

Frequently Asked Questions

Three things. First, format — the right length and BIN pattern for the card type. Second, the Luhn algorithm checksum, which catches most single-digit typos. Third, card type detection from the BIN (Visa, Mastercard, American Express, Discover, and so on). What it doesn't check: whether the card actually exists, whether it's expired, whether there's available credit, or whether it's been reported stolen.

Credit Card Validator

How to Use Credit Card Validator

Enter the card number

View the validation result

Inspect the details

Use it in your dev workflow

When to Use Credit Card Validator

Form input validation

Test data generation

Card type detection

Educational use

Credit Card Validator Examples

Valid Visa

Failed Luhn check

Amex 15-digit

Tips & Best Practices for Credit Card Validator

Frequently Asked Questions

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