Technologies such as Amazon Alexa, Google Voice and Siri have dramatically lowered the bar for voice-based interaction with software. However, a more conversational style of input (voice or text) can be hard to build on top of many existing APIs, especially when it comes to a more stateful style of interaction where a follow-up interaction needs to be aware of the overall conversational context. In this style of interaction, for example, we'd like to inquire about trains from Manchester to Glasgow and then being able to ask "What time is the first departure?" without having to give the context of the conversation again. Normally this context would be present in the initial response we send back to a browser, but in the case of voice interfaces we need to handle this context elsewhere. Conversationally aware APIs can be an example of the backend for front-end pattern where the front-end is a voice or chat platform. This type of API can handle the specifics of this style of interaction by managing conversation states while calling underlying services on behalf of the voice front-end.