Authorize.Net was founded in 1996, in Utah, by Jeff Knowles.
In September 2004, Authorize.Net's servers were hit by a Distributed Denial of Service (DDoS) attack. The DDoS attack lasted for over one week and caused a virtual shut down of the payment gateway's service. The attackers demanded money from Authorize.net in exchange for stopping the attack.
On July 2, 2009, 11pm, the entire web infrastructure for Authorize.net (main website, merchant gateway website, etc.) went offline and stayed down all morning July 3, 2009. None of the over 200,000 merchants who use Authorize.net payment gateway were able to process credit cards. Authorize.net's phone numbers were closed July 3 because of the July 4th holiday as previously announced on their website (though the website was down at the time). Other companies that have nearby offices have reported to the media that there was a fire. Authorize.net started a Twitter account that morning, but did not update their phones to give notice to customers until July 5 when they reopened phones.