A free app for Android, by Single Minded Productions LLC.

Music Speed Changer is the ultimate music player to make your music sound cooler, with the ability to change the tempo and pitch in real time. It also offers an option to change the pitch and speed together, as well as a great looper to make your music more fun to practice.

The Superpowered SDK is an open-source library that allows you to make your Android phone or tablet more powerful. It is built to work with the hardware capabilities of the device, and will not harm the device if used in an application.

It is built for Android devices but may work on other devices with a compatible audio player.