Horsham is a market town formerly trading in cattle, sheep and corn. Its prosperity was built on industries that included brewing, brickmaking, iron-smelting and printing. Although some of these survive, with the exception of iron smelting they are on a small scale and no longer employ large numbers of workers. In 2014 the important industries are financial services, pharmaceuticals and technology. Horsham is a commuter town serving London, Gatwick Airport and the South East Coast.
St Mark’s Court registered office of the RSA Insurance Group

RSA Insurance Group, an insurance company, has its registered office in Horsham. Sun Alliance merged with Royal Insurance in 1996 to form Royal & Sun Alliance Insurance Group, then renamed RSA Insurance Group in 2008. The company first came to the town in 1965 as Sun Alliance, becoming the town’s biggest employer, at its peak it employed 2,500 people, plus the specialised computer centre called Lennox Wood, sited in Southwater country park to which many of the original Horsham computer department staff were relocated. At its peak, the company occupied several smaller premises on the Carfax, Springfield House near St John the Evangelist Roman Catholic Church, the building that is now a study centre in Hurst Road, Parkside and the whole of the St Mark’s complex, and print and security centres in industrial estates sprinkled around Horsham, plus Tricourt House closer to the Carfax and now occupied by a housing association. Parkside has recently been partially occupied by West Sussex County Council after Royal Sun Alliance vacated the building.

There are several web design companies in Horsham as well.