Simple Mandolin Tuner is a must-have app for mandolin players. Developed by musician and electrical engineer Ullrich Vormbrock, this chromatic tuner offers fast and accurate tuning for standard mandolins. With its built-in mic, it recognizes all strings and provides easy and perfect fine-tuning.

The app boasts high usability and cutting-edge signal processing, thanks to Vormbrock's expertise in both music and technology. It features an aesthetic user interface and is optimized for the iPhone X.

Key features of Simple Mandolin Tuner include a default G3-D4-A4-E5 tuning, tone accuracy within +/- 1.0 cents, and a large frequency range from 22 Hz to 1000 Hz. The app also provides a gauge view of the detected tone and octave, allowing for precise tuning by ear.

In addition to the free version, Simple Mandolin Tuner offers in-app purchases for enhanced functionality. These include unlimited duration of reference tone for each string, string protection to prevent over-tightening, calibration options, sensitivity settings, and displays of exact frequency and spectral views of the input signal.

Overall, Simple Mandolin Tuner is a highly recommended app for mandolin players who want a fast, accurate, and user-friendly tuning experience on their iPhone.