SimPy is a process-based discrete-event simulation language based on standard Python and released under the GNU LGPL.

It provides the modeller with components of a simulation model. These include processes for active components like customers, messages and vehicles as well as resources for passive components that form limited capacity congestion points (like servers, checkout counters and tunnels). It also provides monitor variables to aid in gathering statistics. SimPy comes with extensive plotting capabilities.

The distribution contains in-depth documentation, tutorials, and a large number of simulation models.

Simulation model developers are encouraged to share their SimPy modeling techniques with the SimPy community. Please post a message to the simpy-Users mailing list

Subscribe to simpy-users mailing list: http://lists.sourceforge.net/lists/listinfo/simpy-users

Software developers are also encouraged to interface SimPy with other Python- accessible packages, such as GUI, database or mapping and to share these new capabilities with the community under the GNU LGPL.


SimPy requires Python 2.3 or above. Python 3 is not yet supported, but we are working on it.

You can install SimPy easily via PIP (or easy_install):

$ pip install SimPy
$ # or:
$ easy_install SimPy

You can also download and install SimPy manually:

$ cd where/you/put/simpy/
$ python setup.py install

If you want to upgrade an existing installation of SimPy, just add the -U option to pip or easy_install, e.g.:

$ pip install -U SimPy

Getting started

Run one or more of the programs under docs/examples/ to see whether Python finds the SimPy module. If you get an error message like ImportError: No module named SimPy, check if the SimPy packages exists in your site-packages folder (like /Lib/site-packages).

The tutorial and manuals are in the docs/html folder. Many users have commented that the Bank tutorials are valuable in getting users started on building their own simple models. Even a few lines of Python and SimPy can model significant real systems.

For more help, contact the SimPy-Users mailing list. SimPy users are pretty helpful.

Enjoy simulation programming in SimPy!