Ensures credit card numbers are keyed in correctly. Includes checks that the length is correct, the first four digits are within accepted ranges, the number passes the Mod 10 Checksum and that you accept that card. Processes American Express, Australian BankCard, Carte Blache, Diners Club, Discover/Novus, JCB, MasterCard and Visa.

• Free

This script validates user input. It holds all variables submitted by a form and generates XHTML compliant date and time form elements. Offers a complete email contact form to thwart spammers by adding one line of code.

• Free

Contains common data validation routines, such as is_email(), url_responds(), is_country(), etc. for use in your code.

• Free

Use this class to validate your database inputs or mail forms. In the first version it is only possible to validate simple text, numbers (with decimals), (US) dates and email addresses. Invalid form fields will be reported inside a detailed error message. If all form fields are valid you can use the boolean to submit your form.

• Free

Formats addresses to US Postal Service standards and generates XHTML state lists.

• Free

PHP:Form will help you create HTML forms with inbuilt validators, JS validation, automatic refilled fields, and more.

• $4.99
• $599

This function checks card numbers against the MOD10 algorithm, as well as checking card specific features for Mastercard, Visa, American Express and more.

• Free