An Altium developer is responsible for designing and developing electronic circuits and systems using Altium Designer software. They create schematic symbols and PCB footprints, design multi-layer PCB layouts, and perform signal integrity analyses. They also work on debugging and testing prototypes, ensuring compliance with industry standards and client requirements. Additionally, they collaborate with other engineers and designers to optimize designs for manufacturability and cost-effectiveness. Their role often involves managing component libraries and developing custom scripts to automate design tasks. They need to stay updated with new technologies and trends in electronics design and Altium software.