iDefense was founded in May 1998, driven by the fact that information sharing and detailed cyber threat analysis is key to protecting any critical information infrastructure.

Since then, iDefense has been a comprehensive provider of security intelligence to governments and Fortune 500 organizations. The company's goal is to assist customers in avoiding or mitigating threats to their information assets, computers, networks, Internet functions and proprietary information before a crisis occurs, minimizing any potential disruption to network and business operations. Intelligence and analysis are timely, relevant, actionable and fully customizable, delivered round the clock, every day of the year, giving customers intelligence that is specific to their respective environments.

In July 2005, iDefense became an official VeriSign Company, a partnership that combines iDefense intelligence with the resources and innovation of VeriSign.