CircuitMaker is described as 'is the best free PCB design software by Altium for Open Source Hardware Designers, Hackers, Makers, Students and Hobbyists. From the about page of the website:' and is an app in the education & reference category. There are more than 25 alternatives to CircuitMaker for Windows, Linux, Mac and Online / Web-based. The best alternative is KiCad, which is both free and Open Source. Other great apps like CircuitMaker are Fritzing, LibrePCB, Autodesk EAGLE and Circuit Simulator (CircuitJS1).
This electronic circuit simulator is highly interactive giving the feeling of playing with real components. It's very helpful for experimentation and visualization. It's a desktop version of the Circuit JS.
The gEDA project has produced and continues working on a full GPL'd suite and toolkit of Electronic Design Automation tools. These tools are used for electrical circuit design, schematic capture, simulation, prototyping, and production.