pcb
PCB is an interactive printed circuit board editor for Unix, Linux, Windows, and Mac systems. PCB includes a rats nest feature and schematic/netlist import, design rule checking, and can provide industry standard RS-274X (Gerber), NC drill, and centroid data (X-Y data) output for use in the board fabrication and assembly process, as well as photorealistic and design review images. PCB offers high end features such as an autorouter and trace optimizer which can tremendously reduce layout time. For custom requirements, PCB offers a plug-in API for inserting new functionality and using that functionality from within the GUI as well as in scripts.