Instrument Tuner
Standard tuning, at A = 440 Hz.
Turn on Audio, allow audio input, then pick your interface.
Help
Getting started: pick your instrument, then play near your phone or computer microphone, or plug into an audio interface. Turn Audio on, allow audio input when the browser asks, pick your input, then play one string or note at a time.
Strings: Auto works out which string you're playing. Pick a string to tune just that one; the reference buttons play each open string so you can tune by ear. Chromatic shows the nearest note, for voice, winds or any other instrument.
Nothing heard? Allow your browser to use the microphone in your computer's privacy settings (Mac: System Settings > Privacy & Security > Microphone; Windows: Settings > Privacy & security > Microphone). Chrome, Edge and Safari all work.
Privacy: the sound stays in your browser and is never recorded. Standard usage statistics are collected to improve the tuner. See the privacy policy.