Micro-Cap 12 is a free closed-source simulator.
Boasts multipage schematic editor, native digital simulation, Monte Carlo analysis, 33,000 parts in library, worst-case and smoke analysis and Smith charts. Can incorporate spreadsheets. Built-in designer is for active and passive filters. Supported models for active devices include recent MOSFET models. Can read almost any regular Spice or IBIS model. Can export Spice files. More than 2,000 standard digital parts include 7400 families, CD4000 CMOS and ECL. Can view simulation, change component values and watch results update right away. Can create 3-D plots. Outputs netlist for PCB programs including Protel, Accel, Orcad, and PADS. Over 18,000 components in library have packages available. Includes package editor.