OpSim is an open source Chemical Engineering Process Simulator with a user friendly drag-and-drop graphical user interface (GUI) and an underlying high performance simulation engine.

OpSim is cross-platform and runs equally well on Linux, Windows and Macintosh computers.

As a community-driven project under the GNU General Public License (GPL), the public is empowered to make small and large changes to the code base, which leads to new features, responsive bug fixes, and better usability.