OMNeT++ is a component-based, modular and open-architecture discrete event simulation framework. The most common use of OMNeT++ is for simulation of computer networks, but it is also used for queuing network simulations, and other areas as well.
OMNeT++ is licensed under the its own Academic Public License, which allows GNU Public License-like freedom but only in noncommercial settings.[1]
OMNeT++ is not a simulator in itself but rather a simulation framework. Instead of containing explicit and hardwired support for computer networks or other areas, it provides the infrastructure for writing such simulations. Specific application areas are catered by various simulation models and frameworks, most of them open source. These models are developed completely independently of OMNeT++, and follow their own release cycles.