Credit Card Validator

Validate credit card numbers using the Luhn algorithm. Verify card number format and identify card network (Visa, Mastercard, etc.).

100% client-side No signup Free forever

This tool validates the card number format using the Luhn algorithm. It does NOT verify if the card is active, has funds, or check any personal information. All validation is done locally in your browser.

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Test Card Numbers

Use these test numbers for development purposes:

Card TypeTest NumberAction
Visa 4111 1111 1111 1111
Mastercard 5500 0000 0000 0004
American Express 3400 0000 0000 009
Discover 6011 0000 0000 0004
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About Luhn Algorithm

The Luhn algorithm (also known as the mod-10 algorithm) is a checksum formula used to validate credit card numbers and other identification numbers. It was designed to protect against accidental errors, not malicious attacks.

How it works:

  1. Starting from the rightmost digit, double every second digit
  2. If doubling results in a number > 9, subtract 9
  3. Sum all the digits
  4. If the total modulo 10 equals 0, the number is valid
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How to Use Credit Card Validator

How to Validate a Card Number

  1. Enter card number: Type or paste the credit card number (spaces and dashes are ignored).
  2. View results: Instantly see if the number is valid or invalid.
  3. Check card type: See which card network the number belongs to.
  4. View details: See the IIN/BIN information and number length.

Test Card Numbers

These are commonly used test numbers that pass validation but are not real cards:

  • Visa: 4111 1111 1111 1111
  • Mastercard: 5500 0000 0000 0004
  • American Express: 3400 0000 0000 009
  • Discover: 6011 0000 0000 0004
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Features

  • Luhn algorithm validation
  • Card type detection (Visa, Mastercard, Amex, etc.)
  • IIN/BIN range verification
  • Number length validation
  • Format any input (removes spaces/dashes)
  • Real-time validation as you type
  • Test card number generator
  • Card network logo display
  • 100% client-side processing
  • No data transmitted or stored
  • Educational information
  • Free with no registration
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About Credit Card Validator

Credit card numbers follow specific patterns and include a built-in checksum for error detection. Our validator uses the Luhn algorithm to verify number validity and identifies the card network based on the number prefix—without storing or transmitting your data.

What Gets Validated

The validator checks multiple aspects:

  • Luhn checksum: Mathematical verification that the number is properly formed
  • Length validation: Correct digit count for the card type
  • Network identification: Visa, Mastercard, Amex, Discover, etc.
  • Format verification: Proper numeric structure

How the Luhn Algorithm Works

The Luhn algorithm (also called mod-10) doubles every second digit from right to left, subtracts 9 from results over 9, and sums all digits. Valid card numbers produce a sum divisible by 10. This catches single-digit errors and most transpositions.

Card Network Identification

Each network uses distinct prefixes: Visa starts with 4, Mastercard with 51-55 or 2221-2720, American Express with 34 or 37, Discover with 6011 or 65. The validator identifies your card type instantly from the number pattern.

Privacy and Security

All validation happens in your browser—card numbers are never sent to any server. This tool is designed for format verification only: checking if a number follows valid patterns, useful for testing forms or verifying typos in saved cards.

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Frequently Asked Questions

What does credit card validation check?
We validate the Luhn checksum (mathematical verification built into card numbers), identify the card network (Visa, Mastercard, Amex, etc.) from the prefix, and verify length matches the card type. This confirms the number structure is valid, not that it's a real active card.
What is the Luhn algorithm?
The Luhn algorithm is a checksum formula that catches transcription errors. The last digit of every card number is a check digit calculated from the others. Changing any digit produces an invalid checksum. This catches typos before attempting transactions.
Can this tool verify if a card is real?
No - we validate format only, not whether the card exists or has funds. Only the issuing bank and payment processor can verify real cards. Valid format means "correctly structured," not "can be charged." Never attempt to use generated or found card numbers.
How do I identify the card network from a number?
Card networks use specific prefixes: Visa starts with 4, Mastercard with 51-55 or 2221-2720, Amex with 34 or 37, Discover with 6011 or 65, etc. We identify the network and show expected length for validation.
Is it safe to enter card numbers here?
All validation happens in your browser - numbers aren't sent anywhere. However, be cautious entering real card numbers anywhere online. For testing, use known test card numbers from payment processors (like Stripe's test numbers).
Why use this for form validation?
Validating card format before submission catches typos immediately, improving user experience and reducing failed transaction attempts. Implement Luhn validation in your checkout forms for instant feedback. Our tool shows the validation logic you can implement.