Various technologies and techniques are disclosed that provide an integrated debugger simulator. A debugger is provided that allows a user to debug an application in a live mode. A simulator is provided to read recorded data from an earlier point in time in an execution of the application. An integrated debugger simulator is provided by multiplexing the debugger between the application in the live mode and the simulator that reads the recorded data. A simulation mode is provided to allow the user to interact with the recorded data using the debugger. In this simulation mode, the user is able to interact with the recorded data using commands and data views available in the debugger. The user can multiplex between the live mode and the simulation mode from within the debugger.