Filene is one of Callahan's top rivals. Filene's headquarters is in Madison, Wisconsin, and was founded in 1989. Filene operates in the Business Support Services industry. Filene generates 66% of Callahan's revenue.
Gartner has been one of Callahan's top competitors. Gartner was founded in 1979 in Stamford, Connecticut. Gartner is in the Management Consulting Services industry. Gartner generates $3.4B more revenue than Callahan.