Insight Maker is described as 'Explore powerful simulation algorithms for System Dynamics and Agent Based Modeling in a truly cohesive environment. Use System Dynamics to gain insights into your system. Use Agent Based Modeling to granularly break apart the details'. There are five alternatives to Insight Maker, not only websites but also apps for Windows, Linux and Mac. The best alternative is Xcos, which is both free and Open Source. Other great sites and apps similar to Insight Maker are Minsky (Free, Open Source), Simulink (Paid), EMSO simulator (Free, Open Source) and GAMS (Paid).
Minsky enables the simulation of models (particularly from economics) defined in terms of coupled ordinary differential equations. The models are defined using a drawing canvas (rather like VisSim), and a double entry bookkeeping system known as a Godley table.
EMSO simulator is an equation-oriented process simulator with a graphical interface for modeling complex dynamic or steady-state processes. It is CAPE-OPEN compliant. EMSO stands for Environment for Modeling, Simulation, and Optimization.
The General Algebraic Modeling System (GAMS) is a high-level modeling system for mathematical optimization. GAMS is designed for modeling and solving linear, nonlinear, and mixed-integer optimization problems.