A Logisim developer designs and simulates digital logic circuits using Logisim, an educational tool for designing and simulating digital logic circuits. They use built-in components such as logic gates, flip-flops, and input/output pins to create complex circuits. They also test and debug these circuits to ensure they function correctly. Additionally, a Logisim developer may teach or guide others in understanding digital logic design principles. They are often involved in academic or educational environments for teaching computer architecture or digital design courses. Their work is crucial in prototyping and validating digital systems before they're physically built.