EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
Multisim - Multisim is industry standard SPICE simulation and circuit design software for analog, digital, and power electronics in education and research.
Ngspice - Ngspice is a mixed-level/mixed-signal circuit simulator.
Proteus - Proteus - Proteus is a great electrical suite for circuit simulation purposes. You can simulate a single processor or multiple ones at the same time. The application is a great alternative for Virtual System Modelling.
Actran - Actran is a finite element-based simulation software to analyze the acoustic behavior of mechanical systems and parts.