This is a simple web-based voicebot built against api.ai backend. It implements a static client app, as well as a simple web service for doing math.
I used to provide an online functional demo version of this project, but this is no longer available. The API keys contained in the code are no longer working. The code remains available as an educational resource. To run it, you should replace the API keys with your own, and host it on your own.
This is a static web application. Run it with any local or cloud-based web server that can serve static files.
Due to browser voice API microphone security/permission requirements, it’s best to run it over HTTPS, not plain HTTP. From Google docs:
Pages hosted on HTTPS do not need to ask repeatedly for permission, whereas HTTP hosted pages do.
Blog post: How to build a simple web-based voice bot with api.ai