NagBar 1.1.6 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this free Mac application is Volen Davidov.
The software lies within Productivity Tools, more precisely Office Tools. The most popular version among the application users is 1.1. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. You can install NagBar on Mac OS X 10.8 or later.
From the developer:
NagBar is a freeware Nagios, Icinga and Thruk monitoring client which runs in the status bar and give updates about the monitored services. NagBar is a Mac OS X native application created using the Cocoa framework.
The idea for NagBar came from the Nagios Checker plugin for Firefox and Nagstamon.
You may want to check out more Mac applications, such as pdf-DocPro, Simply Notes or Pads X, which might be related to NagBar.