The 1.0 version of oxDrone for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
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. This free software for Mac OS X is a product of Flexatone. OxDrone for Mac lies within Audio & Video Tools, more precisely Music Production.
From the developer:
An endless, polyphonic drone synthesizer with variable waveforms, dynamic low-pass filters, microtonal tuning, and a random parameter generator.