Abstract: A system and method of developing software applications for mobile devices that (a) allows the application to be written once using a high-level application definition language and (b) deploys on devices running different operating systems (OS). The application definition language is agnostic to the operating system and that has constructs to define the complete application including its user interface, data sources, events and actions and business logic. The application definition language is interpreted by the App Virtual Machine at run-time and native Application Programming Interfaces (APIs) are called to create the user interface, display the data from different data sources and execute actions when events occur. The method aims to (a) increase the productivity of the app writers (b) reduce time and cost to develop such software programs for multiple operating systems (c) reduce the amount of source code needed to write an application.