A chronological list of free and open source software for power system analysis follows (the year in parenthesis indicates first release).

· UWPFLOW (1996). This is a research tool that has been designed to calculate local bifurcations related to system limits or singularities in the system Jacobian. The program also generates a series of output files that allow further analyses, such as tangent vectors, left and right eigenvectors at a singular bifurcation point, Jacobians, power flow solutions at different loading levels, voltage stability indices, etc. The program is written in C, and two versions for DOS (16-bit) and UNIX are available, including examples and a brief tutorial. The tool is maintained by Prof. C. A. Cañizares, University of Waterloo, Ontario, Canada.

· TEFTS (1996). This is a simple transient stability program to research Transient Energy Function (TEF) and voltage stability issues in dynamic models of AC-HVDC systems. The program is written in C, and two versions for DOS (16-bit) and UNIX are available, including examples and a brief tutorial. The application is hosted by University of Waterloo, Ontario, Canada.

· MATPOWER (1997). MATPOWER is a package of Matlab M-files for solving power flow and optimal power flow problems. It is intended as a simulation tool for researchers and educators that is easy to use and modify. MATPOWER is designed to give the best performance possible while keeping the code simple to understand and modify. It was initially developed as part of the PowerWeb project. Although MatPower is free and open source, it runs on Matlab, which requires a license. The application is developed by the E&CE group of the Cornell University, Ithaca, New York.

· PSAT (2002). The Power System Analysis Toolbox is a GNU/Octave-based toolbox for electric power system analysis. Main features of PSAT are: Power Flow; Continuation Power Flow; Optimal Power Flow; Small Signal Stability Analysis; Time Domain Simulation; Phasor Measurement Unit (PMU) Placement; User Defined Models; FACTS Models; Wind Turbine Models; Conversion of Data Files from several Formats; Export results to EPS, plain text, MS Excel and LaTeX files; and Interfaces to GAMS and UWPFLOW Programs. PSAT is maintained by Prof. F. Milano, University of Castilla-La Mancha, Ciudad Reaal, Spain.

· InterPSS (2006). The Internet Technology-based Open-source Power System Simulation System is an open-source development project aimed to develop an simple to use, yet powerful Internet technology based software system for design, analysis, and simulation of power systems. Its open and loosely coupled system architecture will allow components developed by others to be easily plugged into the system to augment its functionality, and equally important, allow its components to be integrated into other systems to provide certain power system simulation functionality or services. The project is currently under development by a team of developers living in the United States, Canada and China.

· AMES (2007). The AMES Market Package, developed entirely in Java by an interdisciplinary team of researchers at Iowa State University, is an extensible and modular agent-based framework for studying the dynamic efficiency and reliability of wholesale power markets restructured in accordance with guidelines issued by the U.S. Federal Energy Regulatory Commission. The AMES Market Package is a free open-source tool designed for the study of small to medium-sized systems. It also provides a graphical user interface and output reports through table and chart displays.

· DCOPFJ (2007). The DCOPFJ Package is a free open-source stand-alone solver for small to medium-sized DC optimal power flow problems having a strictly convex quadratic programming (SCQP) formulation. The DCOPFJ solver incorporates QuadProgJ, a dual active-set SCQP solver that has been shown to match or exceed the accuracy of the well-known proprietary QP solver BPMPD when tested on a public repository of small to medium-sized SCQP problems. The DCOPFJ solver has been successfully run on DC-OPF test cases commonly used for training purposes. DCOPFJ is a tool developed entirely in Java by a team of researchers at Iowa State University.