About OpSim

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.

Key features


Free software and the GPL

OpSim is released under the GNU General Public License (GPL, or “free software”).

This license grants people a number of freedoms:

  • You are free to use OpSim, for any purpose
  • You are free to distribute OpSim
  • You can study how OpSim works and change it
  • You can distribute changed versions of OpSim
  • The GPL strictly aims at protecting these freedoms, requiring everyone to share their modifications when they also share the software in public. That aspect is commonly referred to as Copyleft.

Your Work

What you create with OpSim is your sole property. All your work – models, simulations or scripts – including the .opsim files and other data files OpSim can write, is free for you to use as you like. That means that OpSim can be used commercially by engineers, by engineering companies to make commercial simulations, by scientists for research, and by students in educational institutions. OpSim’s GNU GPL license guarantees you this freedom. Nobody is ever permitted to take it away, in contrast to trial or “educational” versions of commercial software that will forbid your work in commercial situations


Who uses OpSim?

Currently OpSim is still under heavy development. This means that OpSim cannot yet be used in academic or commerical environments.

Independent Sites

If you are an independent user / site that references to OpSim and you would like to be mentioned here, please contact the community to add your site here.


Support is given by the community and by the developers.


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.


There are several ways to get in touch with the community. You can;

  • place comments on posts on the OpSim website
  • post on the OpSim google group forum
  • post on the OpSim users mailinglist

Other Useful Links

There is a lot of usefull information to be found on the internet, that OpSim benefits from.

Chemistry databases

  • NIST Chemistry WebBook provides thermochemical, thermophysical, and ion energetics data compiled by NIST under the Standard Reference Data Program.

Other simulators

  • OllinTS is a thermodinamical server (also the Sim42 sources can be found here)
  • DWSIM is An Open Source Process Simulator written in VB.NET and C#
  • COCO (CAPE-OPEN to CAPE-OPEN) is a free-of-charge CAPE-OPEN compliant steady-state simulation environment.
  • ChemSep is a column simulator for distillation, absorption, and extraction operations.