Techniques that enable a third party to author and add functionality to a target application. A third party may create or author a script that encodes the functionality to be added to the target application. The script may then be provided to and executed by the target application, where execution of the script causes the functionality to be added to the target application. In certain embodiments, the added functionality may be in the form of effects that are output via the target application when the script is executed by the target application. The effects may include audio-visual effects that are displayed or output by the target application and may also include displaying data provided by a third party.