DesignSpark PCB is described as 'The World’s Most Powerful Free Schematic and PCB Layout' and is an app in the Education & Reference category. There are more than 25 alternatives to DesignSpark PCB for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Android. The best alternative is KiCad, which is both free and Open Source. Other great apps like DesignSpark PCB are Fritzing (Paid, Open Source), QUCS (Free, Open Source), LibrePCB (Free, Open Source) and Autodesk EAGLE (Free Personal).
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.
TINA Design Suite is a powerful circuit simulation package for analyzing, designing, and real time testing of analog, digital, VHDL, MCU, SMPS, RF, communication, optoelectronic and mixed electronic circuits and their PCB layouts.
With Solve Elec you can : - draw and analyze electrical circuits functioning in direct or alternating current - get literal formulas and values for current intensities and voltages defined in the circuit. - verify circuit related equations. - draw graphs.
PCBWeb is a 100% free Windows desktop CAD application for designing and manufacturing electronics hardware. Features include schematic capture, PCB Layout with gerber output, and Bill of Materials manager.