VocalTuner is a free iPhone app developed by Kiichi Itoh. It falls under the category of Multimedia, specifically Music & Radio. This app serves as a tuner that allows users to visualize the pitch of sound input through the iPhone's microphone. The pitch is displayed as a track line, providing users with a clear view of their accuracy, hiccups, vibrato, and more.

One of the main features of VocalTuner is the ability to play the sound of accurate pitch by tapping the piano keys on the screen. This makes it a useful tool not only for singers but also for tuning and practicing instruments. The app covers a wide range of pitches, from C0 to B7, making it suitable for whistling or vocal bass as well.

In terms of additional features, VocalTuner offers an in-app purchase option to remove ads. Users can also provide feedback and make requests through the app's feedback function or by leaving reviews on the App Store.

Overall, VocalTuner provides a convenient and accessible way for singers and musicians to monitor their pitch accuracy and improve their performance. It's a useful tool for both beginners and experienced performers.