Methods and systems for debugging add-ins using a non-destructive approach. Add-ins are hosted, not stand-alone components, that run in a host application. The add-ins are loaded into an isolated environment so they can be debugged and stopped without affecting the host application. This prevents termination of the host application at arbitrary times. In addition, the host application can refresh itself when an add-in is stepped through in the debugger. The present invention also allows the add-in developer to interact with the host application during a debugging session even when the add-in is stopped at a breakpoint.