Rendering messages having an in-message application

A method for using an in-message application. The method includes: receiving a broadcast message; identifying, in the broadcast message, a reference to an external data provider; obtaining an identifier of the in-message application from the external data provider; using the identifier to identify a set of components of the in-message application, where placement of the set of components is defined by a visual structure of the in-message application, and where each of the set of components is a user interface (UI) element; associating data obtained from the external data provider with a component of the set of components; and serving the broadcast message and the data to a consumer client, where the consumer client renders the in-message application based on the visual structure.