Cocoa Delay is a free, open-source delay plugin in VST format. It focuses on clean design, easy operation, and a warm, lively sound. Notable features: Delay time drift, for giving the wet signal a slight wow/flutter effect Adjustable wet level ducking based on the input signal Static, ping-pong, and circular pan modes Drive section based on open-source Airwindows saturation code Cocoa Delay is free and open-source! If you’re a programmer type, you can check it out on GitHub.
You can also read a manual here.https://github.com/tesselode/cocoa-delay/blob/master/manual.md