From The Apple Wiki
Original author(s)Apple Inc.
Developer(s)Apple Inc.
Stable release
Operating systemiOS
Available inEnglish
LicenseClosed source

AirPlayTester is an app that is present on InternalUI builds. Its purpose is to test AirPlay functionality for audio devices and AirPlay compatible screens. AirPlay is the marketing name of Apple's technology for streaming audio and video between iTunes and iOS devices. It is an evolution of AirTunes that was limited to streaming audio from iTunes to Airport Express base stations.