If you've ever developed a web-based project in Visual Studio, you'll probably know about the need configuration transforms you can do with the web.config file. The downside is that these can't be applied to the app.config for a normal application. There have been several workarounds available including scripting changing the app.config file when a build is performed, but frequently they are not straightforward or easy to configure.there is an easy to configure new alternative though in the form of visual studio extension called SlowCheetah. SlowCheetah allows you to automatically transform the app.config when you press F5 in Visual Studio. Just like with the web.config file, it is possible to have a different transform for each build configuration. Have a read up on how to use SlowCheetah here in the Microsoft Visual Studio Gallery .