LTspice IV is a high performance Spice III simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators.
Gnucap is a general purpose circuit simulator started by Albert Davis in 1993. It is part of the GNU Project. The latest stable version is 0.35 from 2006. The latest development version (as of June 2014) is from April 2013 and is usable.
oregano - An electrical engineering tool for GNOME
oregano is an application for schematic capture and simulation of electronic circuits. The actual simulation is performed by Berkeley Spice, or GNUcap or the new generation ngspice which is required for simulation, but not neces.Discontinued
The last version is from December 2015.
Ngspice is a mixed-level/mixed-signal circuit simulator. Its code is based on three open source software packages: Spice3f5, Cider1b1 and Xspice. Ngspice is part of gEDA project, a full GPL'd suite of Electronic Design Automation tools.
Software for Simulating Voltage and Currents of a text file net-list of a electronics components such as Resistors, Capacitors, inductors, transisters, Diodes, Voltage and Current Sources, etc.
As IC geometries continue to shrink, the need for an accurate circuit simulator is critical. Designers require a highly accurate circuit simulator to precisely predict the timing, power consumption, functionality, and yield of their designs.