Yenka
Solve Elec
simavr
Emulino
Pspice
Circuit Simulator
SimulAVR
PICsim
Circuit Tree
CircuitLab
Logisim
Synopsys VCS
Riviera-PRO
LTspice
BOOLR
Atanua
Circuit Tree is an automation engine that autonomously designs a circuit board design with given user inputs. Using Components define as proprietary models in its database it creates schematic, component placement and routing on the fly. This means that the automation engine auto selects various types of components for a circuit and knows where to place and route these components on board.
Circuit Tree design engine has been designed by engineers who have experience of more than 20 years designing all types of first time right designs.
Yenka Circuit TreeSolve Elec - Solve Elec is a free educational program to draw and analyze electrical circuits.
CircuitLab - Sketch, simulate, and share your circuits, entirely in your browser -- no install required.
simavr - a lean and mean Atmel AVR simulator for linux
Logisim - Logisim is an educational tool for designing and simulating digital logic circuits.
Emulino - an emulator for the Arduino platform by Greg Hewgill
Synopsys VCS - HDL Simulator of System Verilog, Verilog, and VHDL for ASIC design and verification.