1. A computer-implemented method comprising: obtaining, by a server for each of multiple words or sub-words, audio data corresponding to multiple users speaking the word or sub-word; training, by the server for each of the multiple words or sub-words, a hotword model for the word or sub-word based on the audio data for the word or sub-word, wherein the hotword model for the word or sub-word is a model that is used to detect an utterance of the word or sub-word in audio input data without transcribing the word or sub-word from input audio data; storing each of the trained hotword models as a pre-computed hotword model; receiving, by the server, a candidate hotword from a computing device; identifying, by the server, one or more of the stored pre-computed hotword models that correspond to the candidate hotword; and providing, by the server, the identified, one or more of the stored pre-computed hotword models to the computing device.