Stibel left graduate school to start Simpli, a search and marketing company that was sold to NetZero in 2001 and again to ValueClick in 2004. He started Simpli with professors from Brown University (James A. Anderson, Steve Reiss), MIT (Dan Ariely) and Princeton University (George A. Miller), as well as entrepreneurs David Landan, Andrew Duchon, Paul Allopenna, Peter Delgrosso and Carl Dunham. He later helped form United Online, a public company that acquired NetZero and Juno in 2001 and later bought Classmates.com and FTD. In 2005, he left United Online to become the CEO of Interland, a public company that was rebranded by Stibel and team as a new company called Web.com.