There are several free to use app frameworks available on the market. Adobe offers one product for mobile app dev called Flex. This open source app framework lets developers produce apps for mobile operating systems including BlackBerry, Android and iOS. It can also be used to develop for the Tablet operating systems for those brands. Flex also makes it possible to develop in classic environments for desktop applications and browser apps.
Enterprise-class programming
Flex built applications can utilize APIs and device specific options such as the camera, Geosynchronous data, the built in camera(s) and the accelerometer.
Cross-platform
Building with Adobe Flex gives end users the security of stable data and consistent functioning applications.
Server integration
Server integration is also available.