Make app icons of all the sizes you need in a blink! is a webpage for resizing the app icons to meet the requirements of iTunes and Google Play.

Designing an app icon is a thing, while actually using it is another. One of the most hateable requirements of iTunes or Google Play is that you need to prepare a whole set of icons in different sizes.

You can skip reading the guidelines and try which helps you to generate all the sizes you need. Take iOS app for example: Just drag and drop your icon image (best 1024*1024 pixels) to the “toast machine”, and it will create 10 icons for download automatically. Every icon size that iTunes asks for is among the 10 icon sizes. At the same time, you can preview your app icon among other icons on a mobile interface.

It's easy for a designer to adjusting the icon sizes by Photoshop, but since it's so easy, why not using to do it for you?