Centerline vs DaTuner

Centerline is a chromatic tuner for identifying played notes and seeing whether their pitch is flat or sharp. Its chromatic range is 62–800 Hz and follows the nearest note, including sharps and flats. Players can choose Simple, Trail, Strobe, or Workbench displays; Trail shows six seconds of pitch history. Guitar mode detects a string automatically or lets users select one, and includes standard tuning, All Strings progress, and a headstock view. Tuning works offline, and pitch analysis takes place on the device: microphone audio is not recorded, saved, transmitted, or shared. The free Chromatic plan includes the core tuning functions and guitar views. Centerline Complete costs $3.99, paid once and adds alternate and custom six-string tunings, capo settings, A4 calibration from 432–446 Hz, and reference tones. The app is available for Android, iPhone, and Mac. It has no ads or account system; optional usage analytics are disabled until enabled and then exclude audio and pitch data.

DaTuner is an Android chromatic tuner and metronome for tuning instruments, including guitar, bass, violin, ukulele, banjo, cello, piano, and mandolin. It works offline and is designed for noisy environments. Auto-sensitivity can start tuning without manual setup, and users can adjust sensitivity themselves. The display turns green when a pitch is within the optimal tuning range. Screen lock can hold a chosen note, while filter lock isolates a particular note range. Reference frequency can be adjusted manually or set with an external reference for orchestra tuning; the stated sample-rate range is 8kHz to 48kHz. The PRO version adds a strobe display with up to four overtones, transposition, custom temperaments, notation options, a harmonic pitch pipe, and an enhanced tuning algorithm. Google Play says the app may collect and share app information, performance data, and device or other IDs, and that data cannot be deleted. The privacy policy says microphone audio is processed on-device and not stored on company servers.