Duo Security, Inc. provides two-factor authentication as a service to prevent account takeover and data theft. The company’s solutions support authentication via phone calls, SMS-delivered pass codes, mobile applications, push notifications to iPhone, and hardware tokens. It also provides its security platform to help customers protect access to their sensitive data residing in cloud-based applications, including Salesforce, Google Apps, Microsoft Office 365, and Box. The company offers its solutions for VPNs, servers, and Websites. Duo Security, Inc. was founded in 2009 and is based in Ann Arbor, Michigan.