Luhn / Credit Card Validator
Validate identification numbers with the Luhn (mod-10) checksum — credit cards, IMEI, gift cards. Brand detection from BIN, step-by-step doubling visualization, corrected check-digit suggestion, transposition/typo hint, masked display, and bulk list mode with CSV export. 100% client-side — numbers never leave the browser.
About Luhn / Credit Card Validator
Validate identification numbers with the Luhn (mod-10) checksum — credit cards, IMEI, gift cards. Brand detection from BIN, step-by-step doubling visualization, corrected check-digit suggestion, transposition/typo hint, masked display, and bulk list mode with CSV export. 100% client-side — numbers never leave the browser. Everything runs locally in your browser — your data never leaves your device.
How to use
- Enter your input in the tool above.
- Adjust any options to your preference.
- Use the Copy or Download buttons to save the result.
- Everything happens locally — your data never leaves your browser.
FAQ
What is the Luhn algorithm and what does this validator do?
The Luhn (mod-10) algorithm is a simple checksum formula used to validate identification numbers like credit cards, IMEI codes, gift cards, and Canadian SINs. This tool computes the checksum locally in your browser, tells you pass/fail, shows the corrected check digit when validation fails, displays the step-by-step doubling visualization, and detects the card brand from the BIN/IIN prefix.
Which card brands can this tool detect?
Visa, Mastercard (including the 2-series 2221-2720 range), American Express, Discover, JCB, Diners Club, UnionPay, and Maestro. Each brand has known BIN/IIN prefixes and allowed lengths — the matcher prefers the longest prefix so 622126-622925 correctly resolves to Discover rather than UnionPay, and 3528-3589 resolves to JCB.
Can I validate IMEI, gift card, or other non-card numbers?
Yes. Choose a mode: Credit Card (12-19 digits), IMEI (14 digits + check digit = 15), Gift Card (configurable 12-19 digits), or Any (no length constraint). The Luhn algorithm itself is mode-agnostic; modes only constrain accepted length and turn off brand detection for non-card inputs.
Does this tool store or transmit my card numbers?
Never. Every computation runs 100% client-side in JavaScript. There is no server endpoint, no analytics on the input field, and no console logging of card data. The history feature (last 20 operations) stores only a count and timestamp in localStorage on this device — never the card numbers themselves.
What extra features does this tool have versus other Luhn validators?
(1) Single-number live validation with pass/fail. (2) Eight-brand BIN detection. (3) Step-by-step doubling visualization. (4) Corrected check-digit suggestion on failure. (5) Adjacent-transposition hint (catches the most common typing error). (6) Four display formats (plain, spaced, dashed, grouped 4-6-5 for Amex). (7) Masked display toggle. (8) Four input modes (credit, IMEI, gift, any). (9) Bulk paste with per-line valid/invalid table. (10) CSV export of bulk results. (11) Wikipedia + Stripe canonical test vectors. (12) localStorage history (max 20, no numbers stored). (13) Shareable URL with mode + format encoded in fragment.
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