In order to do so, this new version comes with a clearly defined API.
GNOME-tagger is a desktop application, writen in python and GTK3, developed as a GNOME application which is an alternative to the tagger web application. With it you can, add tags to packages, vote on tags (up vote or down vote), see the statistics about tags on the fedora package collection as well as see who is winning the tagger game. Pretty much all what you can do from the web application, but locally :-)
This is still a little bit work in progress as we still need to assess how we want to handle authentification and the blacklist of tags as well as anonymous tags but hopefully we will have this new version ready soon and you can start playing with gnome-tagger!
Note: The new tagger API supports rating apps as well, but at the moment this something integrated with gnome-software but not with tagger web application or gnome-tagger.