Exchange simulators mimic the behaviour of Exchanges/Trading Venues. They are used for end-to-end testing of trading strategies, trading algorithms, and other systems that connect to or interact with Exchanges.
Models and strategies can be fine-tuned and adjusted using one set of data and can be further tested against other market data sets across events or trading days of particular interest. Data can be replayed at varying speeds to test capacity or latency constraints.
Exchange simulators can also be used to test the connectivity layer of the user system with the exchange and can help identify issues at the protocol and/or network level.