A system and method for developing modularized applications are disclosed. In one preferred embodiment, a modularized application 12′ is implemented as a directory-hierarchy comprises a plurality of directories, with each directory 20 containing a module-implementation definition 22 for implementing an application module 14′ for performing one of the application's tasks. Directory relationship 26, such as parent-child, is used in defining modules association for inter-module communication. In one preferred embodiment, when executing a modularized application, modules' module-implementation definitions 22A 22B are used by application runtime, for running hardware processes 24A 24B performing the modules' intended tasks, and for conducting inter-module communication 28 between hardware processes 24A 24B of associated modules 14A″ 14B″.