A tuner that holds the note.

Press Start Listening and your browser will ask for the microphone. Play one note and the reading settles instead of jumping between neighbors.

Play a note

Press spacebar to start/stop • Microphone permission required

The microphone is only opened when you press start, and released when you stop or leave the page. A4 is fixed at 440 Hz; there is no calibration control and nothing is saved between visits. It runs in a browser, on a phone or tablet on the stand as well as on a desktop.

Why this tuner holds a note

A tuner that twitches is not measuring badly, it is usually measuring a signal the browser has already mangled, and then believing every frame of it.

The voice-call processing is off

Browsers open a microphone with echo cancellation, noise suppression and automatic gain control switched on, because most pages want a phone call. All three are wrong for an instrument: they duck sustained tones, chase the level, and treat a bowed or blown note as noise to clean up. This tuner asks for the microphone with all three disabled.

It waits before it commits

Pitch comes from the YIN algorithm with the microphone offset removed first. The frequency then goes through a Kalman filter, and the note itself through a lock that needs four frames in a row agreeing before the display commits to a name. Small bends hold the note you are playing; a real change unlocks it.

Low notes are in range

Detection runs from 27 Hz up to 2 kHz. That floor is below the low B on a five-string bass, so cello C, double bass and the bottom of a baritone sax are all comfortably inside it, where tuners built around a voice range give up. The cents readout is smoothed in cents rather than in hertz, because a hertz of wobble means very different things at the two ends of that range.

The audio never leaves the browser

The signal is analyzed frame by frame in the page and thrown away. Nothing is recorded, nothing is uploaded, and no account is involved, so there is nothing to sign in to and nothing stored about what you played. Stop, close the tab or navigate away and the microphone is released.

In tune but not in time? The metronome is on the next page.

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