Credit Card Validator
Validate card number format using the Luhn algorithm and detect card type. 100% client-side.
⚠️ Security Warning
- • Never enter real card numbers into any online tool — use test cards for learning.
- • This tool validates format only — it does not verify that a card is real, active, or has funds.
- • Real validation requires a payment processor (Stripe, Braintree) and the cardholder's authorization.
- • This tool runs entirely in your browser — nothing is transmitted, but the risk of browser extensions or malware still applies.
0 digits entered
🧪 Test card numbers (safe to use)
These are official test numbers from payment processors — they have valid format but no real funds. Use them for testing.
🔒 100% private: All validation happens in your browser. Nothing is transmitted. Luhn algorithm per ISO/IEC 7812.
About Credit Card Validator
Credit card numbers follow a standardized format defined by ISO/IEC 7812. A card number is 13–19 digits and includes a check digit computed with the Luhn algorithm (also called "mod 10"). This check digit catches typos — about 90% of single-digit errors and most transposition errors are detected. The first 6–8 digits are the Issuer Identification Number (IIN, formerly BIN), identifying the card network (Visa, Mastercard, Amex) and the issuing bank. This tool validates a card number with the Luhn algorithm, detects the card type from the IIN prefix, checks CVC/CVV format, and validates expiry dates. IMPORTANT: This tool validates FORMAT only. It does not verify that a card is real, active, or has funds — that requires a payment processor and the cardholder's consent. Never enter a real card number into any online tool.
How It Works
- Enter a card number (test cards are fine — real cards should not be entered).
- The tool runs the Luhn algorithm to check the check digit.
- Card type is detected from the IIN (Issuer Identification Number).
- Optionally enter expiry and CVC to validate their format.
- See a detailed breakdown: digits, validity, card brand, Luhn pass/fail.
✨ Key Features
- ✓Luhn algorithm validation
- ✓Card type detection (Visa, Mastercard, Amex, Discover, Diners, JCB, Maestro, UnionPay)
- ✓Digit-by-digit breakdown of the Luhn computation
- ✓CVC/CVV format validation (3 or 4 digits based on card type)
- ✓Expiry date validation (MM/YY format, not expired)
- ✓IIN prefix detection
- ✓Card number formatting (grouped by 4)
- ✓Sample test card numbers
- ✓Educational breakdown of why a card is valid or invalid
- ✓100% client-side — no card data ever transmitted
🎯 Common Use Cases
- →Learning how credit card validation works
- →Testing card format validation in your own app
- →Understanding the Luhn algorithm step-by-step
- →Verifying the format of test card numbers
- →Debugging card validation logic during development
- →Educating users about credit card formats
- →Checking card type from a BIN/IIN prefix
- →QA testing payment forms with test cards
💡 Advanced Tips & Pro Insights
- ▸The Luhn algorithm is a checksum, not a security feature. Attackers can easily generate Luhn-valid numbers. Real validation requires a payment processor.
- ▸Card ranges: Visa starts with 4. Mastercard starts with 51–55 or 2221–2720. Amex starts with 34 or 37 (15 digits). Discover starts with 6011, 65, or 644–649. JCB starts with 3528–3589.
- ▸The 3-digit CVV (Visa, Mastercard, Discover) or 4-digit CID (Amex) is on the back of the card. The Amex CID is on the front.
- ▸Test card numbers (from payment processors): Visa 4242 4242 4242 4242, Mastercard 5555 5555 5555 4444, Amex 3782 8224 6310 005.
- ▸Never log or store full card numbers (PAN). PCI-DSS requires masking (show only last 4 digits) and tokenization for storage.
- ▸For production apps, use a payment processor SDK (Stripe Elements, Braintree Hosted Fields) that handles card data without it touching your server.
Frequently Asked Questions
Is this credit card validator free?▾
Yes, this credit card validator is completely free with no signup, email, or usage limits.
Is it safe to enter my real card number?▾
NEVER enter a real credit card number into any online tool — including this one. Even though this tool runs 100% client-side and never transmits anything, entering real card details into any webpage carries risk (e.g., browser extensions, malware). Use official test card numbers for testing. This tool is for education and format verification only.
What is the Luhn algorithm?▾
The Luhn algorithm (also called "mod 10") is a simple checksum formula used to validate credit card numbers. It sums digits with alternating doubling, and the total must be divisible by 10. It catches typos and most transposition errors but is not a security mechanism.
What does Luhn-valid mean?▾
Luhn-valid means the check digit is correct — the number has the right format. It does NOT mean the card is real, active, or has funds. Anyone can generate Luhn-valid numbers with an online generator.
How is card type detected?▾
By the Issuer Identification Number (IIN) — the first 6–8 digits. Each card network has reserved ranges (Visa: 4, Mastercard: 51–55 and 2221–2720, Amex: 34 and 37). The IIN also identifies the issuing bank.
What are the test card numbers?▾
Common test cards (all valid format, no real funds): Visa 4242 4242 4242 4242, Mastercard 5555 5555 5555 4444, Amex 3782 8224 6310 005, Discover 6011 1111 1111 1117. Use these for testing payment forms.
Can this tool verify a card is active?▾
No. Only a payment processor (Stripe, Braintree, Adyen) with the cardholder's authorization can verify a card is active and has funds. This tool only checks the format.
What about PCI-DSS compliance?▾
PCI-DSS is a security standard for handling credit card data. Never store or log full card numbers (PAN) unless you are PCI-DSS certified. Use tokenization (Stripe, Braintree) so card data never touches your servers.