The wide variation in features and capabilities of mobile devices lead to difficulties in the development of the same application on different platforms. Therefore we propose an online model-driven integrated development environment to provide developers with a platform-independent GUI design for mobile applications. Our proposed system transforms an abstract platform-independent GUI into a platform-dependent GUI on a target platform. The generated project is entirely in the form with which an experienced developer on the platform is already familiar. Furthermore, as the generated application is not a web-based one, it can access naturally native features of a platform. The proposed flexible architecture enable the capability to handle and update different abstract UI and non-UI controls needed to design GUIs for mobile applications. Experimental results with volunteers show that our proposed solution can save up to 25-51% time to create GUIs of an application to three different platforms of Android, iOS and Windows Phone.