Credit Card Validator
Validate credit card numbers using the Luhn algorithm and detect card types
Enter Credit Card Number
Numbers are automatically formatted as you type
Important Information
• This tool only validates the mathematical correctness and format of card numbers
• It cannot verify if a card actually exists, is active, or has available credit
• All processing is done locally in your browser - no data is sent to our servers
• Use this tool for testing payment forms or educational purposes only
• Never use real card numbers in online tools - use test card numbers instead
Test Card Numbers
Use these test numbers to try the validator (these are not real cards):
Valid Test Numbers
- 4532015112830366 (Visa)
- 5555555555554444 (MasterCard)
- 378282246310005 (American Express)
- 6011111111111117 (Discover)
Invalid Test Numbers
- 4532015112830367 (Invalid Luhn)
- 555555555555444 (Too Short)
- 37828224631000555 (Wrong Length)
- 1234567890123456 (Invalid Pattern)
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About This Tool
How It Works
- Uses the Luhn algorithm to validate card number mathematics
- Detects card brand based on number patterns
- Validates number length for the detected card type
- All processing happens in your browser - no data sent to servers
Common Use Cases
- Testing payment form validation logic
- Verifying manually entered card numbers
- Learning about card number formats and validation
- Debugging payment processing issues
Frequently Asked Questions
What does this credit card validator check?
This tool validates credit card numbers using the Luhn algorithm (also known as the "modulus 10" algorithm), detects the card type (Visa, MasterCard, American Express, etc.), and verifies that the number length matches the expected format for the detected card type. It only checks mathematical correctness and format - it cannot verify if a card actually exists or is active.
How does the Luhn algorithm work?
The Luhn algorithm is a checksum formula used to validate credit card numbers. It works by doubling every second digit from right to left, subtracting 9 from any result over 9, then summing all digits. If the total is divisible by 10, the number passes the Luhn check. This catches most typing errors and prevents random numbers from appearing valid.
Is it safe to use this tool with real credit card numbers?
We strongly recommend against using real credit card numbers with any online tool. This validator processes everything locally in your browser without sending data to our servers, but for security best practices, only use test card numbers or dummy data. Real card numbers should only be entered on secure, PCI-compliant payment pages.
What card types can this tool detect?
The tool can detect major card types including Visa (starts with 4), MasterCard (starts with 5 or 2221-2720), American Express (starts with 34 or 37), Discover (starts with 6011 or 65), Diners Club (starts with 30, 36, 38), JCB (starts with 35), UnionPay (starts with 62), and Maestro. Each card type has specific length requirements that are also validated.
Why do some valid-looking numbers fail validation?
A number might look valid but fail for several reasons: it might not pass the Luhn algorithm check, have the wrong length for its card type, or not match the number pattern for any known card brand. The Luhn algorithm is specifically designed to catch common data entry errors like transposed digits.
Can I use this tool to test my payment forms?
Yes, this is an excellent tool for testing payment form validation logic. Use the provided test card numbers to verify that your forms correctly accept valid numbers and reject invalid ones. Most payment processors also provide their own test card numbers for integration testing.
What are the test card numbers provided?
The tool includes several test card numbers that are mathematically valid but not tied to real accounts. These include Visa (4532015112830366), MasterCard (5555555555554444), American Express (378282246310005), and Discover (6011111111111117). There are also invalid test numbers to demonstrate different types of validation failures.
Why does the card number get formatted automatically?
The tool formats numbers with spaces every 4 digits to improve readability and match how card numbers typically appear on physical cards. This formatting is purely visual - the validation logic works with the underlying digits. The spaces are automatically removed during processing.
What happens if I enter a number that is too short?
The tool waits until you enter at least 12 digits before showing validation results, as most credit card numbers are between 12-19 digits long. If a number is too short for its detected card type, the length check will fail and the overall validation will show as invalid.
Can this tool generate valid credit card numbers?
No, this tool only validates existing numbers - it does not generate new card numbers. Generating valid card numbers would require creating numbers that pass the Luhn algorithm while following card type patterns, but such generated numbers should never be used as real payment methods.
How accurate is the card type detection?
The card type detection is based on official numbering patterns used by card networks and is highly accurate for major card brands. However, some regional cards or newer card products might not be recognized. The tool focuses on the most common international card types that most payment systems support.
Does this tool work for debit cards too?
Yes, the Luhn algorithm and card type detection work for both credit and debit cards, as they follow the same numbering standards. The tool cannot distinguish between credit and debit cards since they use the same number formats - that distinction is made at the issuing bank level, not in the card number itself.