A system includes persistent storage containing predefined user interface (UI) component templates and a representation of a web page that includes a runtime UI component configured to reserve an empty portion of the web page to be populated by UI components generated at runtime. The system also includes a processor configured to perform operations, including receiving, from a client device, a request for the web page, and determining, based on the request, that the web page includes the runtime UI component. The operations also include determining runtime parameter values associated with the request, and determining, based on the runtime parameter values and the predefined UI component templates, context-specific UI components to populate the empty portion of the web page. The operations further include generating a context-specific representation of the web page based on the context-specific UI components, and transmitting, to the client device, the context-specific representation.