gEDA is a suite of electronic design automation (EDA) tools. Currently, the project offers a mature suite of free software applications for electronics design, including schematic capture, attribute management, bill of materials (BOM) generation, netlisting into over 20 netlist formats, analog and digital simulation, and printed circuit board (PCB) layout.
HDLmaker generates hierarchical Verilog and VHDL code, PCB netlists, simulation and synthesis scripts/projects/make files, and schematics. It can translate Verilog/VHDL and HDLmaker projects into HTML, including extensive hyperlinking between the modules. It can also translate PADS PCB netlists into Verilog and VHDL and can do some simple VHDL to Verilog translations. HDLMaker synplifies the development of complex FPGAs and ASICs, and has extensive support for most Xilinx FPGAs.
Ngspice is a mixed-level/mixed-signal circuit simulator based on three open source software packages: Spice3f5, Cider1b1, and Xspice. Spice3 is the most famous and widely used circuit simulator. Cider is mixed-level simulator that includes Spice3f5 and adds DSIM, a device simulator. Cider couples the circuit level simulator to the device simulator to provide greater simulation accuracy (at the expense of greater simulation time). Xspice is an extension to Spice3 that provides code modeling support and simulation of digital components through an embedded event driven algorithm.
XCircuit is a UNIX/X11 program for drawing publishable-quality electrical circuit schematic diagrams and related figures, and producing circuit netlists through schematic capture. XCircuit regards circuits as inherently hierarchical, and writes both hierarchical PostScript output and hierarchical SPICE netlists. Circuit components are saved in and retrieved from libraries which are fully editable. XCircuit does not separate artistic expression from circuit drawing; it maintains flexiblity in style without compromising the power of schematic capture.