Facebook Messenger is a replacement for other chat clients, now that Facebook has deprecated its chat API. It provides the same Web experience right on your Desktop.
What’s new in version 1.0
Updated on Jun 05 2015
Version 1.0 (1.0-beta2):
Fix bug beep on first keypress
Fix login/logout opening in a new window
Hide image upload icon, only drag and drop supported
It's a pretty big faux pas on the part of a developer to give their own app a five-star rating, especially one that's just a desktop wrapper of a web app.
Free
Application is not under development & not supported.