About TUNEZOID

TUNEZOID is a chromatic tuner for guitar and bass that runs in a browser tab. There is nothing to install, no account to make, and no audio ever leaves your device.

How it hears you

When you allow microphone access, the page reads the incoming audio and works out the fundamental frequency of the note you are playing, many times a second. That frequency is compared against the string you are aiming for, and the needle shows how far off you are in cents. All of it happens inside the browser tab, using the Web Audio API. No recording is made and nothing is uploaded.

Eighteen tunings, checked three ways

A tuner that names the wrong note is worse than no tuner at all, so the tuning data is checked more carefully than most of what we build. Each tuning is stored as a list of semitone offsets. The label you read on screen, something like OPEN G: D G D G B D, is written out separately by hand rather than generated from those offsets, and a test checks the two agree. Written the other way round they would agree by construction and a typo would simply rewrite the label to match itself.

Labels carry no octave, so a third check writes every tuning out in scientific pitch and asks an independent music theory library which MIDI number each written pitch is. Without it, an offset mistyped by exactly twelve semitones would have read as correct everywhere. Both checks were made to fail on purpose before they were trusted.

Every tuning has a page of its own, with each string's note and frequency: see all tunings.

Install it

TUNEZOID is a progressive web app. Add it to your home screen and it opens full screen and works with no connection at all, because the files it needs are cached on your device the first time you visit. One consequence worth knowing: an installed copy can be one version behind until you next launch it.

Who makes it

TUNEZOID is one of a small family of music tools built by an independent developer. The others are a metronome, a guitar chord reference and a piano chord reference. They share a look and a set of ideas but each is its own site.

Questions, corrections and bug reports are welcome at [email protected]. See the contact page for what is useful to include.