The Naemon project includes a GUI, but not the old Nagios CGI interface - instead we have a fast, modern and more useful replacement, Thruk. You can test the online demo of Thruk at demo.thruk.org.
We also bundle Livestatus, which is how Thruk communicates with the core.
We’d like for more relevant tools to join our project. As we’re about to be an independent entity, we want our name to be a guarantee that we are owned by our members who work together.