Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Dialogflow - Conversational UX Platform. (ex API.ai)
Expensive Chat - Chatroom where you pay per letter
Hie Chat - Know what your friends are doing and chat without typing
Botpress - Open-source platform for developers to build high-quality digital assistants
Subreply - A super simple web app where content is king, its a text only social network that has a strong focus on the value of comment threads.