RASA

Open source machine learning tools for developers to build, improve, and deploy text-and voice-based chatbots and assistants. (cit. RASA github home).

RASA is probably the most important tool to develop "task-oriented" conversational application. Despite the RASA official statement, is not originally developed to manage voice interaction, but chatbots. RASA consist in two main components:

• RASA NLU is based upon DIET, a a refined state of the art intent/entities classifier
• RASA Core (now called RASA Dialog Manager), based on TED, a machine learning algorithm, to manage multi-turn dialogs, escaping the traditional state-machine based way, but instead allowing conversation developers to insert "stories", set of sequences of intents-actions examples. In a sense, developers define the conversational agent dialog manager giving examples (the stories).

RASA own a huge open community of developers and researchers. It's probably the biggest open source project to develop on-premise "production-ready" complex dialog systems. All the development ecosystem is around the Python programming language.

References

home page: https://rasa.com/

github: https://github.com/RasaHQ/

community forum: https://forum.rasa.com/