Unlike board-level designs composed of discrete parts, it is not practical to breadboard integrated circuits before manufacture.

The SPICE simulators help to predict the behavior of the IC under different operating conditions, such as different voltage and current levels, temperature variations, and noise.

[15] SPICE source code was from the beginning distributed by UC Berkeley for a nominal charge (to cover the cost of magnetic tape).

[18] Since then, the open-source or academic continuations of SPICE include: XSPICE,[19] developed at Georgia Tech, which added mixed analog/digital "code models" for behavioral simulation; CIDER[20] (previously CODECS), developed by UC Berkeley and Oregon State University, which added semiconductor device simulation; Ngspice,[21][22] based on SPICE 3f5; WRspice,[23] a C++ re-write of the original spice3f5 code.

Berkeley SPICE inspired and served as a basis for many other circuit simulation programs, in academia, in industry, and in commercial products.

[27] Today a few IC manufacturers, typically the larger companies, have groups continuing to develop SPICE-based circuit simulation programs.

[29][30] Other companies maintain internal circuit simulators which are not directly based upon SPICE, among them PowerSpice at IBM, TITAN at Infineon Technologies, Lynx at Intel Corporation, and Pstar at NXP Semiconductors also.

[31] SPICE became popular because it contained the analyses and models needed to design integrated circuits of the time, and was robust enough and fast enough to be practical to use.

Parametric sweeps were added to analyze circuit performance with changing manufacturing tolerances or operating conditions.

Harmonic balance or time-domain steady state analyses were added for RF and switched-capacitor circuit design.

However, a public-domain circuit simulator containing the modern analyses and features needed to become a successor in popularity to SPICE has not yet emerged.

Also, application of transient analysis with default simulation parameters can lead to qualitatively wrong conclusions on circuit dynamics.

SPICE3 retains the netlist for circuit description, but allows analyses to be controlled from a command-line interface similar to the C shell.

[38] So one may obtain electrical power dissipation, resulting in self-heating causing parameter variations, and cooling system efficiency in a single simulation run.

Again this is achieved by mapping mechanical onto the electrical elements (torque → voltage, angular velocity → current, coefficient of viscous friction → resistance, moment of inertia → inductance).

[39] So again the final model consists of only SPICE compatible lumped circuit elements, but one gains mechanical together with electrical data during simulation.

[40] Electromagnetic modeling is accessible to a SPICE simulator via the PEEC (partial element equivalent circuit) method.

[41] Maxwell's equations have been mapped, RLC, Skin effect, dielectric or magnetic materials and incident or radiated fields have been modelled.