The APE file extension is used for Monkey's Audio lossless format, a fast and easy way to compress digital music. APE file is the default audio song with Monkey lossless compression method.
The APE file extension is used by Audio Visualization Studio (AVS) plug-in in Winamp. APE stands for 'VS Plug-in Effect. APE file is saved in binary format. APE file contain extra effects for AVS, and this is distributed as a visualization plug-in with Winamp.