Download of ZenTuner 0.3.0 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This free Mac app was originally developed by JP Simard. 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. The application lies within Audio & Video Tools, more precisely Music Production.
From the developer:
Zen Tuner is a minimal chromatic tuner. It works well with any instrument, whether it's woodwinds, brass, strings or voice. The app provides large current note representation and a high marker that changes from red to green when the note is in tune. It comes with an easily accessible dropdown that lets you easily tune all instruments. You just click the main note to adjust preference.
You may want to check out more Mac applications, such as Resound, SoundByte or Lounge Lizard Session, which might be similar to ZenTuner.