A Knowledge Engineering developer is involved in the design and development of artificial intelligence systems. They work on creating knowledge-based systems that can process information similar to how a human would. This involves designing knowledge databases, developing algorithms and systems to manipulate knowledge and solve complex problems. They may also develop models and systems for machine learning and artificial intelligence applications. Their work enables machines to mimic human intelligence, thereby improving efficiency and decision-making capabilities. They often collaborate with data scientists, AI researchers, and other professionals to implement AI technologies in various sectors.