http://browsersync.io/ - at least the server side seems to be open.

Nope. This is a chrome feature that just happens to have the same name as that site. There is no connection.

No, it's http://browsersync.io/ - the readme links directly to that site: https://github.com/google/web-starter-kit#features

I stand corrected. This is a design-time tool. I mistook it for the consumer feature of the same name.