Credit Card Validator
Validate credit card numbers using the Luhn algorithm. Check Visa, Mastercard, American Express, and other card types instantly.
Enter Credit Card Number
Enter 13-19 digits. Spaces are automatically formatted.
Test Card Numbers (For Testing Only)
- Visa: 4532 1488 0343 6467
- Mastercard: 5425 2334 3010 9903
- American Express: 3782 822463 10005
- Discover: 6011 1111 1111 1117
Note: These are test numbers only. This validator checks format, not if a card is active or has funds.
How Credit Card Validation Works
Our credit card validator uses the Luhn algorithm (also called mod-10 algorithm) to verify that a credit card number is mathematically valid. This is the same method used by banks and payment processors worldwide.
Luhn Algorithm Steps:
- Starting from the rightmost digit, double every second digit
- If doubling results in a number greater than 9, subtract 9
- Sum all the digits together
- If the total is divisible by 10, the card number is valid
What This Validator Checks:
- Card number length (13-19 digits)
- Luhn algorithm checksum
- Card type detection (Visa, Mastercard, Amex, etc.)
- Does NOT check if card is active or has funds
- Does NOT verify expiration date or CVV
Frequently Asked Questions
Should I actually enter my real credit card here?
Honest answer: You can, and it's technically safe (everything runs in your browser, never hits our servers). But general life advice: Don't enter your real credit card on random websites. Use the test numbers we provided instead. This tool is mainly for developers testing payment forms, accountants checking invoices, or curious people wanting to understand how card validation works.
If it says "valid," does that mean the card works?
Nope! Big misconception here. This only checks if the math is right—it's using something called the Luhn algorithm. Think of it like checking if VIN on a car looks correct. It doesn't tell you if the car runs, who owns it, or if it's stolen. Same deal with cards: We can't see if it's active, expired, blocked, or has $10 vs. $10,000 on it. Only your bank knows that stuff.
Which card types does this recognize?
Visa, Mastercard, American Express, Discover, Diners Club, and JCB. Basically all the major ones you'd find in your wallet. Each card brand has a unique pattern—Visa always starts with 4, Mastercard with 51-55, Amex with 34 or 37. The validator knows these patterns and can identify the card type instantly. Pretty neat, right?
Why do some random numbers I make up still pass?
Pure luck! If you type 16 random digits, there's about a 10% chance they'll pass the Luhn check by accident. That's why real card numbers have that check digit calculated mathematically—it catches typos. If you transpose two numbers (like 1234 becomes 1324), it'll almost always fail validation. That's the whole point.