I don't think I could release my app without this tool. It single handedly creates all the output sizes I need to release my app to the Apple App Store and Google Play Store, from one design. I haven't come across another tool that even comes close!!
It's easy to use with a lot of templates. As an app developer screenshots plays a big role for conversion. App Screens makes it easy to generate and try out with different kinds of screenshot.
AppScreens