Modular operators can be regarded as maneuvers of platform development. In the context where system interfaces can be standardized and system components can be developed and marketed by a group of technologically and commercially interdependent firms, direct and indirect network effects are crucial to a platform’s success. In this article, we synthesize theories of modularity and network economics to provide a theoretical framework of platform development. The framework shows the applicability of modular operators in developing a platform, and helps the platform provider leverage the force of network effects by platform strategy-making.