Fritzing is an open-source electronic design automation (EDA) tool focused on maker and educational use. It provides three interconnected views (breadboard, schematic, PCB) for circuit design, with features including component placement, wiring, autorouting, ngspice simulation, microcontroller code editing/upload (Arduino, PICAXE), and export to Gerber, PDF, SVG, and other formats. The application is built as a monolithic Qt/C++ desktop app with a modular internal architecture: model layer (ModelPart, ModelBase), view layer (SketchWidget subclasses), command pattern for undo/redo, and dedicated subsystems for parts management, SVG rendering, and design rule checking. It relies on external libraries such as Boost (graph algorithms), Clipper (polygon operations), QuaZip (ZIP handling), libgit2 (parts repository updates), and ngspice (simulation). The codebase is actively maintained with ongoing Qt6 migration, though some legacy patterns and workarounds remain.