Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
upverter - Upverter makes it easy to design and share electronics on the web.
QUCS - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit.
Ktechlab - KTechLab is an IDE for microcontrollers and electronics.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite