Free simulation software

SPICE (Simulation Program with Integrated Circuit Emphasis) is a general-purpose, open-source analog electronic circuit simulator. It is a program used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.

circuit-design system

EPANET (Environmental Protection Agency Network Evaluation Tool) is a public domain, water distribution system modeling software package developed by the United States Environmental Protection Agency's (EPA) Water Supply and Water Resources Division. It performs extended-period simulation of hydraulic and water-quality behavior within pressurized pipe networks and is designed to be "a research tool that improves our understanding of the movement and fate of drinking-water constituents within distribution systems". EPANET first appeared in 1993.

OpenModelica is a free and open source environment based on the Modelica modeling language for modeling, simulating, optimizing and analyzing complex dynamic systems. This software is actively developed by Open Source Modelica Consortium, a non-profit, non-governmental organization. The Open Source Modelica Consortium is run as a project of RISE SICS East AB in collaboration with Linköping University.

FreeHAL was a volunteer computing project to build a self-learning chatbot. This project is no longer active.

KTechLab is an IDE for electronic and PIC microcontroller circuit design and simulation; it is a circuit designer with auto-routing and a simulator of common electronic components and logic elements.

Computer program for antenna modeling

computer program for efficiently reducing the complexity of digital electronic gate circuits

free software for transport simulation

CalculiX is a free and open-source finite-element analysis application that uses an input format similar to Abaqus. It has an implicit and explicit solver (CCX) written by Guido Dhondt and a pre- and post-processor (CGX) written by Klaus Wittig. The original software was written for the Linux operating system in 1998. Convergent Mechanical has ported the application to the Windows operating system.

Ngspice is an open-source mixed-level/mixed-signal electronic circuit simulator. It is a successor of the latest stable release of Berkeley SPICE, version 3f.5, which was released in 1993. A small group of maintainers and the user community contribute to the ngspice project by providing new features, enhancements and bug fixes.