Abstract: This disclosure describes, in part, techniques implemented by a speech-processing system for providing an extensible skill-interface component to facilitate voice-control of third-party developer devices. The speech-processing system may provide the skill-interface component to third-party device developers using a web-based portal through which the skill interfaces may be created to voice-enable third-party devices having unique capabilities. For instance, a skill interface may define events, such as voice commands of a user, which map to directives configured to cause the third-party devices to perform an operation that is responsive to the event. In this way, the speech-processing system may receive audio data representing a voice command of a user in an environment of a third-party device, and return a directive to cause the third-party device to perform an operation responsive to the voice command.