Methods, systems, and apparatus for determining that a software application installed on a user device is compatible with a new voice action, wherein the new voice action is specified by an application developer of the software application. One or more trigger terms for triggering the software application to perform the new voice action are identified. An automatic speech recognizer is biased to prefer the identified trigger terms of the new voice action over trigger terms of other voice actions. A transcription of an utterance generated by the biased automatic speech recognizer is obtained. The transcription of the utterance generated by the biased automatic speech recognizer is determined to include a particular trigger term included in the identified trigger terms. Based at least on determining that the transcription of the utterance generated by the biased automatic speech recognizer includes the particular trigger term, execution of the new voice action is triggered.