iMASSBAL is the internet version of the popular MASSBAL simulation sytem. iMASSBAL is a true open equation based simulation sytem. iMASSBAL consists of a downloadable graphical flowsheeting tool (GFT) with links to the MASSBAL.com server for simulation runs. The first month is free and then it is US0.02 per variable, per SUCCESSFUL run. Standard features of iMASSBAL include mass, energy and momentum steady state balances, dynamic simulation (in batch run mode), off-line data reconciliation and off-line optimization. Stand alone versions of MASSBAL are capable of being commissioned on-line for on demand and real time applications such as equipment performance monitoring and real time optimization.