Perhaps surprisingly, each company is thriving 15 years later. ESET, for instance, still makes the annual Deloitte Fast 500 EMEA list of rapidly growing I.T. companies, and averaged sales growth of 303 percent over the last five years.
When asked about the success stories, local business leaders in the Slovak capital of Bratislava cited the strong education provided under communist rule.
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"I think socialism had a couple of very good things—the health care system and the education system," said Tomas Martinec, the head of boutique asset management firm Metatron, in a statement that was echoed by others.
Luckily for aspiring programmers, I.T. and cryptography, as well as physical sciences, were strengths of Czechoslovak universities, with the Soviet Union mindful of the skills needed to the fight the Cold War.
"We have an excellent history in maths, physics and I.T.," the head of the Slovak Investment and Trade Development Agency, Robert Simoncic, told CNBC. "IBM employs more people in Slovakia than in Poland."
One beneficiary of the education system was Miroslav Trnka, who studied at the Slovak University of Technology before setting up ESET in Bratislava. His rivals at avast! meanwhile, were based at Prague's renowned Mathematical Machines Research Institute.
Or not rivals, but old friends, according to Trnka. He met avast!'s founders in Czechoslovakia's fledgling programing scene of the 1980s and 90s, when young enthusiasts attended lectures, clubs and competitions together.
"I have known both the founders of these companies, AVG and avast!, for a very long time," he told CNBC.
"I met the owners of avast! even before they established the company. They also started making programs before the revolution--we cooperated at the time."