|Original author(s)||Imagine That Inc.|
|Developer(s)||Imagine That Inc.|
|Operating system||Windows 10, 8.1, 8, 7 Service Pack 1, Server 2016, Server 2012, or Server 2008 R2|
|Type||Simulation & Optimization|
|License||Proprietary, Individual, Node-Locked, and Floating Licenses|
ExtendSim (formerly known as Extend) is a simulation program for modeling discrete event, continuous, agent-based, discrete rate, and mixed-mode processes. There are three ExtendSim packages: CP for continuous processes; DE which adds discrete event technology; and Pro which adds discrete rate and reliability block diagramming modules.
|1987||Original release for continuous modeling on the Macintosh|
|1989||Discrete event capabilities added|
|1992||Hierarchical modeling, Cloning, Animation, Interactivity|
|1994||Sensitivity Analysis, interface to Microsoft Excel|
|1995||Release for Microsoft Windows|
|1998||Scripting, Activity-Based Costing|
|2001||Optimizer, ActiveX/COM and ODBC support, source code debugger|
|2007||Changed product name from Extend to ExtendSim, internal database|
|2008||Discrete rate and 3D capabilities added|
|2010||Scenario Manager, Advanced Resource Manager|
|2013||ADO database support, Flow attributes|
|2018||Integrated reliability diagramming, cloud-based ASP|
Models are created by dragging blocks from a library into a model worksheet. Blocks are connected together to create the logical flow of the model. Data for the model resides in the parameters of the blocks and in a proprietary database. New blocks can be created by combining existing blocks into a single hierarchical block or by programming a block in ExtendSim's c-based language, ModL. The major libraries in ExtendSim are:
|Library name||Purpose||Sample blocks|
|Value||Mathematical calculations, remote data access, statistics collection||Math, Equation, Read, Write, Mean & Variance|
|Item||Models discrete event processes||Queue, Activity, Resource Pool, Item|
|Rate||Models discrete rate processes||Tank, Valve, Interchange|
|Reliability||Reliability block diagramming||Start Node, Component, End Node|
|Chart||Displays plots and charts||Bar, Scatter, Histogram|
|Report||Reporting model results||Reports Manager, Cost Stats, Item Log Manager|
|Animation3D||Animates the model state||Animate Item, Animate Value|
|Utilities||Model interface, debugging, and information||Buttons, Record Message, Memory Usage|
Sample applications include resource optimization for food logistics, six sigma process improvement for a hospital emergency department, communication systems, and manufacturing facility design 
- Discrete event simulation
- Computer model
- Process optimization
- Simulation software
- list of discrete event simulation software
- "Resource Optimization by Simulation Technique in Food Logistics" (PDF). Archived from the original (PDF) on 2011-07-20. Retrieved 2011-02-11.
- "Simulating Six Sigma Improvement Ideas for a Hospital Emergency Department" (PDF). Retrieved 2011-02-11.
- "NCW End-To-End (NETE) Model For Future C2 Architecture Assessments" (PDF). Retrieved 2011-02-14.
- "Facility Design: Simulation Methodology for Facility Design". Archived from the original on 2011-10-03. Retrieved 2011-02-14.