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.
Gnu Circuit Analysis Package is a general purpose circuit simulator. It performs nonlinear DC and transient analysis, fourier analysis, and AC analysis. Spice compatible models for the MOSFET (level 1- 7) and diode are included. This project is not based on Berkeley Spice, but some of the models have been derived from the Berleley models. It was formerly known as 'Al's Circuit Simulator'.
TkGate is an event-driven digital circuit simulator with a TCL/Tk-based graphical editor. It supports a wide range of primitive circuit elements and user-defined modules for hierarchical design. The distribution comes with a number of tutorial and example circuits which can be loaded through the "Help" menu, and the example circuits include a simple CPU, programmed to run the Animals game. TkGate has multi-lingual support for English, Japanese, French, German, Spanish, Welsh, and Catalan.
The Eagle EDA software is composed of tightly integrated modules for PCB design, including Schematic Capture, Board Layout, and Autorouter. There is a free full-function (only board size limited) non-commercial license available for hobby and educational use as well. Windows, DOS, and of course, Linux versions are available.