Play one open string at a time. The dial fills green and the strobe stops drifting within 5 cents of pitch.
Tap a string to hear its reference pitch.
Detection runs a normalised square difference function over a 4096 sample window, so it tracks the fundamental rather than the loudest harmonic. Low E at 82.41 Hz resolves cleanly. The strobe drifts left when you are flat and right when you are sharp, at a speed set by the size of the error, so it settles before the dial does.
Clicks are scheduled ahead of time against the audio clock rather than the browser timer, so the pulse holds steady while the page is busy. The accent lands on beat one and its lamp turns green.
Tap the outer ring for a major key, the inner ring for a minor. The lit slices either side of your key hold the chords that sit closest to it.
Chords in this key
Tap any of them to hear it strummed. Roman numerals in capitals are major, lower case are minor, and the small circle is diminished.
Why the notes sit in this order
Count up seven semitones from C and you land on G. Do it again and you get D, then A, then E. Keep going and you pass through all twelve notes before you arrive back at C. That jump of seven semitones is a perfect fifth, and stacking fifths is what puts the notes in this order rather than the alphabetical one.
The order does something useful. Each step clockwise adds one sharp to the key signature, and each step anticlockwise adds one flat. C has none. G has one. D has two. Read the wheel clockwise and you are reading the key signatures in order.
What it tells you
Two keys next to each other share six of their seven notes. That single note of difference is why a song can slide between neighbouring keys without anyone flinching, and why a jump to the opposite side of the wheel sounds like a jolt. Distance round the circle is distance in sound.
The inner ring holds each major key's relative minor. A minor uses the same seven notes as C major and starts somewhere else, which is why swapping between them changes the mood without changing a single note.
How to use it
Pick your key on the outer ring for major or the inner ring for minor. The chord row underneath fills with the seven chords built on that key, numbered with Roman numerals: capitals for major, lower case for minor, a small circle for diminished.
Start with I, IV and V. Almost every song in a major key leans on those three. Add vi and you have the four chords behind a large slice of pop music, which is what the I–V–vi–IV button plays. When a song stops sounding interesting, borrow a chord from a neighbouring slice: it shares six notes with where you are, so it fits without sounding random.
One step clockwise takes you to the dominant. Moving there mid‑song is the most common key change in popular music, usually to lift a final chorus.
Neighbouring slices share six of seven notes, which is why a key and the two either side of it sound settled together. The inner ring holds each key's relative minor: same notes, different home. Move one slice clockwise and you have modulated to the dominant, the most common key change in popular music.
C chords
Tap any chord to open it full size, scroll through the ways to play it, and see what goes with it.
Shapes assume standard tuning. Each chord appears in open position where one exists, then as movable E shape and A shape barres, so the same fingering slides up the neck to any root. Blue dots are the root note.
C major
Drag the neck sideways for frets 8 to 15
Blue dots are root notes. Start and finish on one and the shape will sound like the key rather than a run of notes.
Fifteen frets in standard tuning. The pattern repeats every twelve frets, so anything you learn in the first position works again at the octave. Pentatonic shapes drop the two notes that most often clash over a chord, which is why they are forgiving under a solo.
Tap the neck
Tap any fret to name the note. Tap several and it works out the chord.
Drag the neck sideways for frets 8 to 15
Chord naming works from the set of pitch classes you pick, so an inversion comes back as a slash chord: the name of the chord over the note you put in the bass. Two notes are named as an interval instead. Some sets have more than one honest name, and where that happens the alternatives are listed underneath.
Intervals play the lower note first, then the higher one, then both together. Chords arrive as a strum. Roots are chosen at random inside the middle of the guitar's range, so you are naming the distance rather than memorising a pitch.
Lessons
One lesson is open in this preview. The rest are outlines of where the course goes next.
Every sound here is synthesised on the fly, so there are no samples to load. The kick is a sine wave dropping from 150 Hz to 48 Hz, the snare is filtered noise plus a tuned body, and the cymbals are noise through a high shelf. Jazz and blues run on a triplet grid so the shuffle is real rather than approximated. Patterns are generated for the bar you ask for rather than stored, so the kick keeps landing on the odd pulses and the snare on the even ones however long the bar is. The 8 signatures are compound, counted in dotted beats of three. In 7/8 the count is straight eighths grouped two, two, three, so the two swung styles play straight there.
Write
Tab out an idea before it goes.
Tabs live in this browser tab only. Close it and they are gone. Accounts and real saving come later.
New tab
Drag a note sideways to hold it across more beats. On a desktop, drag a box across the grid to select several at once.
Click any cell in the grid, then type a fret number. Two digits within a moment give you the twelfth fret rather than a one and a two. Arrow keys move, space steps forward, backspace clears.
Notes carry their length into playback, so a held chord rings while the lead moves over it. Shift with the left and right arrows stretches the selected note. Space plays and stops. The fretboard marks the notes in your key, which is a suggestion rather than a rule.
Colour
The wash behind everything.
Tuner face
How the tuner shows you the error.
Default tuning
What the tuner opens on.
Playback tone
The guitar you hear when the app plays a note back to you. Write keeps its own tone per track.
Location
Off unless you turn it on. Nothing is sent anywhere.
The country comes from your device's time zone, because the app makes no network calls and there is nothing to ask. The coordinates come from the browser and stay in it.
Reading the name
Chords that go with this
Fingers are numbered from the index at 1 to the little finger at 4. A T means fret that string with your thumb over the top of the neck, which is how a lot of players take the bass note of an F or a Cadd9.