Credit Card Validator

Validates credit card numbers and identifies card types.

Please enter a card number

What is a Credit Card Validator?

This tool allows you to easily check the validity of credit card numbers. It analyzes the input card number and determines whether it is valid and which credit card type (Visa, MasterCard, American Express, etc.) it corresponds to. It's a valuable resource for developers, testers, and e-commerce site operators working with payment systems.

A Credit Card Validator is a tool that verifies whether an entered credit card number has a valid format and is mathematically correct according to the Luhn algorithm (the international standard for credit card number verification). It also automatically identifies the card issuer (Visa, MasterCard, American Express, etc.) based on the number pattern.

Developers, testers, and e-commerce site operators can use this tool to easily test credit card processing systems and validate input data.

The Luhn Algorithm

The Luhn algorithm (also known as the modulus 10 algorithm) is a simple checksum formula used to validate identification numbers, especially credit card numbers. The algorithm is executed in the following steps:

  1. Starting from the rightmost digit, double every second digit
  2. If the result of doubling is greater than or equal to 10, use the sum of the digits (e.g., 12 → 1+2 = 3)
  3. Sum all digits (original digits and transformed digits)
  4. If the total is divisible by 10, the card number is valid

This algorithm can detect simple typographical errors and random errors, but it might not detect intentionally falsified numbers.

How to Use

  1. Enter a credit card number in the text field
  2. The following information will be displayed according to the input:
    • Validation result (valid/invalid/incomplete/format error)
    • Card brand (Visa, MasterCard, American Express, etc.)
    • Formatted number display (properly spaced according to the card brand)
    • Security code information (CVV/CVC etc.)
    • Valid card length information

You can enter credit card numbers with spaces or hyphens. For example, the following input formats are all valid:

  • 4111111111111111
  • 4111 1111 1111 1111
  • 4111-1111-1111-1111

Key Features

  • Luhn Algorithm Validation: Checks if the entered credit card number passes validation based on the Luhn algorithm
  • Card Type Identification: Automatically identifies the card brand (Visa, MasterCard, American Express, Discover, etc.) from the number pattern
  • Format Verification: Verifies if the card number length and pattern are correct
  • Real-time Validation: Results are displayed in real-time as you type
  • Visual Display: Visual representation of a credit card to see the information in a realistic format
  • Security Code Information: Displays the security code type (CVV/CVC) and length according to the card type
  • Valid Length Display: Shows the appropriate valid length for each card type
  • Secure Design: All processing happens in the browser; no data is sent to any server

Supported Card Brands

This validator can automatically identify the following major credit card brands:

  • Visa (VISA): Numbers that start with 4, 13-19 digits (example: 4111111111111111)
  • MasterCard (MASTERCARD): Numbers that start with 51-55 or 2221-2720, 16 digits (example: 5555555555554444)
  • American Express (AMERICAN_EXPRESS): Numbers that start with 34 or 37, 15 digits (example: 378282246310005)
  • Discover (DISCOVER): Numbers that start with 6011, 622126-622925, 644-649, or 65, 16-19 digits (example: 6011111111111117)
  • Diners Club (DINERS_CLUB): Numbers that start with 300-305, 36, or 38-39, 14-19 digits
  • JCB: Numbers that start with 3528-3589, 16-19 digits (example: 3530111333300000)
  • UnionPay (UNIONPAY): Numbers that start with 62, 16-19 digits
  • Maestro (MAESTRO): Numbers that start with 5018, 5020, 5038, 5893, 6304, 6759, 6761, 6762, or 6763, 16-19 digits
  • Elo (ELO): Card numbers with specific patterns used in Brazil
  • Mir (MIR): Cards used in the Russian national payment system
  • Hipercard (HIPERCARD): Cards with specific patterns used in Brazil
  • Hiper (HIPER): Cards with specific patterns used in Brazil

Use Cases

Development and Testing Environments

When developing e-commerce sites or payment systems, you can verify that various test card numbers are processed correctly.

// Test Visa number
4111111111111111 → Valid card number (Visa)

// Test American Express number
378282246310005 → Valid card number (American Express)

Debugging and Problem Solving

When troubleshooting payment errors reported by users, you can quickly check whether the entered card number is structurally correct.

// Verify a reported error card number
4111-1111-1111-1112 → Invalid card number (Luhn check failure)

Troubleshooting

Card Brand Shows "Unknown Card Brand"

This occurs when the first few digits of the credit card number do not match the defined patterns. Check the following:

  • Whether the number has been entered correctly
  • Whether the card brand is supported (if not, it will be displayed as "Unknown")

Understanding Validation Results

"Valid Card Number"

This is displayed when the card number meets all the following conditions:

  • Passes the Luhn algorithm check
  • Matches the required length for the identified card brand
  • Follows the pattern specifications of the card brand

"Incomplete Card Number"

This is displayed when:

  • A card brand can be identified (e.g., "35" at the beginning identifies as JCB)
  • But the number fails the Luhn algorithm check or has insufficient digits

"Invalid Card Number"

This could be due to the following reasons:

  1. Failed the Luhn algorithm check (incorrect check digit)
  2. Inappropriate length of the card number
  3. Card number pattern does not match the prescribed format
  4. Card brand cannot be identified

"Invalid Format" is Displayed

The card number may contain characters other than numbers (except spaces and hyphens). Use only numbers, spaces, and hyphens.

Notes

  • This tool operates entirely client-side. Your credit card information is never sent to any server
  • This validator only checks the structural validity of the card number and does not verify if the actual card is valid (expiration date, balance, etc.)

Test Credit Card Numbers

Here are examples of test credit card numbers (not actual card numbers):

  • Visa: 4111111111111111
  • MasterCard: 5555555555554444
  • American Express: 378282246310005
  • Discover: 6011111111111117
  • JCB: 3530111333300000

These numbers are structurally valid but cannot be used for actual transactions.