http://localhost:35729/
is the URL to the live reload server. It is only used for managing live reload, not serving your actual website.
Typically, one would use grunt-contrib-connect to serve static sites with grunt. Then view their site by going to localhost:8000 or wherever you've configured it to reside. But depending on your needs, it could be apache, nginx, etc serving files as well.
There is a livereload
option on grunt-contrib-connect as well. This only injects the <script src="//localhost:35729/livereload.js"></script>
tag into your HTML and nothing else.