KiCad

A complete open-source electronics design suite covering the whole path from schematic to manufacturing: schematic editor, component assignment, PCB layout with interactive routing, design rule checking, and a 3D view of the finished board. Unlike the free editions of commercial tools, it places no limit on board area or layer count — which is the main reason it became the default in academic projects and open hardware. Component libraries ship with it, and manufacturer libraries can be added.