Work by Authorize.net

Authorize.Net is a payment gateway service provider allowing merchants to accept credit card and electronic checks payments through their Web site and over an IP (Internet Protocol) connection. Authorize.Net claims a user base of over 305,000 merchants, which would make them the Internet's largest payment gateway service provider. In November 2007 Cybersource purchased Authorize.Net for $565 million. Authorize.Net was originally purchased in 2004 by Lightbridge for $82 Million.

http://www.authorize.net/