Voting machines are privately manufactured and developed and, as with other many other IT systems, the code is typically proprietary. The Open Source Election Technology Foundation is pushing for an election system that is owned “by the people of the United States” One major election technology company, Dominion Voting Systems, develops its systems in the U.S. and Canada but also has an office in Belgrade, Serbia. Dominion says it takes measures “to ensure the accuracy, integrity and security of the software we create for our products””]
Source: https://www.csoonline.com/article/3128032/one-election-system-vendor-uses-developers-in-serbia.html