BanjoTuner is a free iPhone application developed by Hsing-Fu Hsueh. It falls under the category of Multimedia, specifically Music & Radio, and is designed to assist banjo players in tuning their instruments. The program supports 4, 5, and 6-string banjos, with a total of 18 tuning modes available.

The tuner feature of BanjoTuner allows users to adjust the A4 frequency within a range of 428 to 452 frequencies. It provides a visual scale for precision tuning, with each sub-bit representing 10 cents. When the pitch is accurate, a green arrow is displayed, turning white if the pitch difference exceeds a sub-bit. The complete function visually indicates whether the pitch is good or not, with a lighting arrow guiding users to easily adjust the string.

In addition to the tuner, BanjoTuner also includes a metronome feature. The operation screen is intuitive and easy to use, with all functions accessible on the same page. Users can choose from 18 beat modes, ranging from Grave to Prestissimo, with BPM values specified for each mode. The application supports "segment beat" function, allowing for double, triple, and quad beat subdivisions. It also offers a pendulum display mode and timing display to help users control their practice time. The Real Time Playback (RTP) mode ensures precise beat and supports dynamic shifting.

BanjoTuner is a versatile and user-friendly tool for banjo players, providing accurate tuning and metronome functions to enhance their playing experience.