Credit Card Validator

What this tool does

Credit Card Validator checks a card number against the Luhn (mod-10) checksum algorithm used by every major card network, and detects the likely network, Visa, Mastercard, American Express, Discover, Diners Club, JCB or UnionPay, from its prefix and digit length. Nothing is transmitted anywhere.

Every major card network uses the Luhn algorithm, a simple mod-10 checksum, as a basic typo-catching check baked into the card number itself, independent of whether that specific account actually exists or is active.

This tool runs that same checksum against any entered number and separately detects which network it likely belongs to, Visa, Mastercard, Amex, Discover, Diners Club, JCB or UnionPay, purely from its prefix digits and length, entirely in your browser with nothing ever transmitted anywhere.

How to use Credit Card Validator

1. Enter the Card number (spaces and hyphens are ignored).
2. Review the Luhn checksum result.
3. Check the detected Likely network.
4. Confirm the Digit count matches what you expect for that network.

Tips for better results

• A "valid" Luhn result only means the digits are internally self-consistent, not that the card is real, active, authorised, or belongs to anyone; it catches typos and transposed digits, nothing more.
• Each network has its own set of valid prefixes and lengths (for example, Amex is always 15 digits starting with 34 or 37); an unrecognised combination simply means the number doesn’t match any known pattern this tool checks.
• This never transmits, stores, or logs anything you enter; checking happens entirely within your own browser session.
• Developers commonly use well-known test numbers (like 4111 1111 1111 1111 for Visa) that pass Luhn specifically for testing payment integrations without using a real card.

Common use cases

• Verifying a card number was typed correctly before submitting a payment form.
• Testing payment form validation logic during development with known test numbers.
• Understanding which network a card number belongs to from its digits alone.
• Learning how the Luhn checksum algorithm actually works, digit by digit.

Common mistakes to avoid

• Treating a "valid" result as proof a card is real or chargeable; the Luhn check only confirms internal digit consistency, not authorisation, funds, or even that the number was ever issued.
• Entering a real card number into any online tool, including this one, when a well-known test number would do just as well for checking format or checksum logic.
• Assuming an "unrecognised" network means the number is definitely invalid; it may simply belong to a smaller or regional network not covered by this tool’s prefix table.