An Icarus Verilog developer creates, tests, and debugs digital design circuits using the Icarus Verilog simulation and synthesis tool. They write code in Verilog, a hardware description language, to define and simulate electronic circuits. The developer also conducts functional and timing simulations to validate design functionality and performance. They use Icarus Verilog to convert the Verilog code into a form that can be used for FPGA or ASIC design. The developer collaborates with design teams, understands design specifications, and ensures compliance with coding standards. Lastly, they troubleshoot any issues that arise during the design process.