Tuner

Chromatic, with presets for guitar, bass, ukulele and violin.

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How it works

It uses your device's microphone: the sound is not recorded or sent anywhere.
Notes are detected with the YIN algorithm, accurate to a few cents; in a noisy room, bring the instrument closer.
You can change the reference A (432 or 442 Hz, say) and choose C D E or Do Re Mi names.

Everything happens on this device: no file is uploaded and nothing leaves the browser.