Insight Maker is a powerful simulation tool that runs right in your web browser. Best of all, it's completely free! Insight Maker supports the following features and more:

Building Models
Use Insight Maker to start with a conceptual map of your Insight and then convert it into a complete simulation model. Insight Maker supports extensive diagramming and modeling features that enable you to easily create representations of your system.
System Dynamics Modeling
Causal Loop Diagrams
Stock and Flow Models
Graphical Inputs
Ghosting Primitives
Vectorizing Primitives
Extensive Units Support
Agent Based Modeling
States and Transitions Diagrams
Custom Actions
Spatial Relationships
Network Relationships
Diagraming and Rich Pictures
Extensive Styling Features
Custom and Built-in Library of Pictures
Folding and Unfolding of Portions of Diagram
Loop Identification
Run Models
Insight Maker supports powerful simulation methods that rival many commercial programs. With Insight Maker you can use System Dynamics modeling, Agent Based Modeling or integrate the two methods seamlessly.
Times Series and Scatterplots/Phase-Planes
Maps and Network Diagrams
Tables Data Export to CSV
Time Machine Analysis
Functions and Programming
Large Library of Built-In Functions
User Created Macros and Functions
Imperative Programming
Functional Programming
Object-Oriented Programming
Simulation Algorithms
Euler's Method
4th Order Runge-Kutta Method
Sensitivity Testing
Model Scripting
Built-In Optimizer
Sharing Models
Insight Maker has extensive capabilities for sharing your models with others. Just send them a link or embed your model in your website or blog. Also, you can give others access to your models, so they can work on them collaboratively with you right in their own browsers.
Send Model Link
Embed Model in a Web Page
Access Control
Enable Shared Editing
Make Insights Private or Public
Cost Free!