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Free simulation software

OpenSIMPLY is an open source discrete-event simulation software.

It is free simulation software with no restrictions on number of simulation events.

It runs on Windows and Linux on 32-bit and 64-bit platforms as a graphical or terminal application.

OpenSIMPLY is a modeling software with very high simulation performance.

Free download simulation software.

Download executable demos containing classical queuing system models.


As open source software, the project currently supports Delphi and Lazarus/Free Pascal dialects.

Computer simulation with OpenSIMPLY is intuitive and easy.

You only need a few lines to run a model. Look at the simulation examples.

The OpenSIMPLY package contains a step-by-step tutorial based on runnable examples to get started quickly, detailed documentation, and pop-up help for the Delphi and Lazarus IDEs.

Simulation levels

The OpenSIMPLY as a simulation modeling software offers two subsystems which provide the discrete-event simulation approach at different levels.

The high level, block simulation, provides a palette of ready-to-use simulation components (blocks) representing queue, server, router, etc., which are connected in the required order. Any simulation block can be extended in terms of parameters and functionality.

Using a low, Simula-like level, much faster simulation models can be created. Even the models in the Simula programming language (with some adaptation) can be run with OpenSIMPLY.

Both simulation levels can be used together. Simulation blocks may describe the general behavior of a model. The time-critical section can be implemented using low level simulation technique.

Learn more about the simulation styles.

Notable features

The OpenSIMPLY provides global, selective and deferred statistics gathering modes. The latter mode allows the user to take into account the steady state of the model in order to avoid a significant decrease in the accuracy of the results.

The project provides full flexibility to describe the behavior of the model providing the dynamic model feature. The blocks may be relocated during the simulation, so the model configuration can be changed on runtime.

Areas of use

Scientific research

One run of the model of the system under study gives a single point of the characteristic of interest. For the simplest (linear) function, two points are sufficient. Usually, most characteristics require at least several points for the function curve plotting. In practice, quite a lot of such points are required in order to cover the range under study without making a mistake (for example, for non-monotonic functions). For an acceptable error of the simulation results, the number of entities in the model should be large enough to run, especially for complex systems. Therefore, the simulation software should run very fast so that you don't have to wait years to get results.

OpenSIMPLY is very fast simulation software and capable of automatically performing multi-run simulations of the same model with different input data. Built-in flexible formatted output is suitable for both approximation tables and visualization. Learn more.


OpenSIMPLY is great for educational purposes. With a clear and simple approach to simulation, beginners make fewer mistakes but can focus more on modeling. Learn more.

Some applications

Traffic simulation Initially, the project was developed for traffic analysis with a clear and simple modeling ideology. Using the built-in traffic theory routines, the simulation results can be verified for some degenerate cases. Even some complex models can be checked too. Learn more.

Network simulation A fairly complex and large networks can be simulated with OpenSIMPLY as well. Simulation blocks for network routers, packet filters, broadcasts, and more simplify the creation of network architecture models. The entire network route of any packet can be saved and analyzed. Learn more.

Licenses and special requirements

OpenSIMPLY is free computer simulation software. Learn more about the using.

For extra features or for special license write a message.