Validate credit card numbers using the Luhn algorithm. Detect card type and check for valid formatting.
Enter card number without spaces or dashes (they will be added automatically)
These are valid test numbers for development purposes only.
Do not use real card data or any numbers you are not authorized to test.
Six brands, identified by their Issuer Identification Number prefixes and expected lengths: Visa (starts with 4, 13, 16, or 19 digits), Mastercard (51-55 or 22-27 starts, 16 digits), American Express (34 or 37, 15 digits), Discover (6011 or 65, 16 or 19 digits), JCB (35, 16 or 19 digits), and Diners Club (300-305, 36, or 38, 14 or 16 digits). Numbers matching no pattern are reported as Unknown.
No. The Luhn algorithm is a mod-10 checksum that catches typos and random-digit mistakes; it cannot confirm a card exists, is active, or has available credit. The tool performs purely mathematical validation and never contacts any bank or payment network.
The format check compares your digit count against the lengths allowed for the detected brand. When the count does not match, the message states exactly which lengths that brand uses, for example 15 for American Express or 14 and 16 for Diners Club, so a mistyped digit count is easy to spot.
As you type, digits are grouped into blocks of four with spaces, and the input accepts up to 19 characters. The formatted result follows brand conventions: American Express renders as 4-6-5 groups and 14-digit Diners Club as 4-6-4, while everything else stays in fours. The built-in test number buttons fill the input and validate in one click.
Nothing you type is stored or transmitted; the Luhn math, brand detection, and formatting all run in your browser with no network activity. Even so, the page itself advises using only the provided development test numbers or cards you are authorized to check.