He wrote his first antivirus program 1988, two years after the appearance of the first computer virus. He entered business began with his friend Eduard Kučera at the end of the communist regime in 1989, when he founded Alwil. In the early 1990s, the company was renamed Avast Software, based on its best known product, Avast Antivirus. It soon faced intense competition, especially from Symantec, which used an aggressive pricing policy in a bid to lead the market. In response Baudiš and Kucera took a radical defense strategy, offering its product for free. As a result, Avast ultimately emerged as the largest anti-virus firm in the world.