Press Release - May 25, 2007

Authorize.Net to Present at the Cowen and Company 35th Annual SMid-Cap Technology Conference on May 31, 2007

MARLBOROUGH, MA, May 25, 2007 (MARKET WIRE via COMTEX News Network) — Authorize.Net Holdings, Inc. (NASDAQ: ANET), a leading e-commerce company, today announced that it will be presenting at the Cowen and Company 35th Annual SMid-Cap Technology Investor Conference being held in New York. Robert Donahue, Chief Executive Officer, and Timothy O'Brien, Chief Financial Officer of Authorize.Net, will be presenting on Thursday, May 31, 2007 at 8:45 AM ET. There will be a webcast of this presentation which can be accessed at www.authorize.net in the Investor Relations section and will be archived for 30 days.

About Authorize.Net

Authorize.Net provides secure, reliable, Internet Protocol (IP)-based payment gateway solutions that enable merchants to authorize, settle and manage electronic transactions anytime, anywhere, via websites, at retail, mail order/telephone order (MOTO) call centers and on wireless devices. In addition to its payment solutions, Authorize.Net offers extensive value-add products designed to help merchants manage their business, fight fraud, and improve profitability. Authorize.Net is sold through an extensive network of partners that offer its IP-based payment services to their merchant customers.

AUTHORIZE.NET and the Authorize.Net logo are registered trademarks of Authorize.Net Holdings, Inc. All other marks are the property of their respective owners.

Investor Contact
Timothy O'Brien
Authorize.Net
508-229-3215
Contact via http://www.marketwire.com/mw/emailprcntct?id=3B9B94DFF9D752D1

SOURCE: Authorize.net