Polyrhythm - Rhythm Trainer is a free Android app developed by Autumn Rock Software Development. It falls under the category of multimedia and specifically music and radio. The app is designed to help musicians master polyrhythms, a technique that involves playing two or more rhythms simultaneously.

The app's core features include an easy-to-use polyrhythm metronome that allows you to select various types of polyrhythms. The playback is accompanied by a visual representation of the rhythm you have selected. Additionally, you can turn on/off specific beats to help you practice syncopated rhythms. The "TAP" button is available to quickly change tempo. Overall, Polyrhythm - Rhythm Trainer is an excellent tool for musicians who want to improve their polyrhythmic skills.