Rhasspy (pronounced RAH-SPEE) is an open source, fully offline voice assistant toolkit for many languages that works well with Home Assistant, Hass.io, and Node-RED.

meSpeak.js (modulary enhanced speak.js) is a 100% client-side JavaScript text-to-speech library

Speech and natural language tools

TextBlob is a Python (2 and 3) library for processing textual data. It provides a simple API for diving into common natural language processing (NLP) tasks such as part-of-speech tagging, noun phrase extraction, sentiment analysis, classification, translation, and more.