Master Key

A piano-learning app for Android. Plays a MIDI file as a falling-note highway descending onto a drawn keyboard, optionally alongside the real engraved score, and is built for someone who is learning to read music rather than someone who already can.

What it does Falling-note highway. Notes descend to a key line where a piano keyboard is drawn. Note height is duration, so held notes are visibly long. Right hand is amber, left hand is teal, and that colour means the same thing everywhere — on the falling note, on the notehead in the score, and on the key it lands on.

It picks the keyboard range for you. Drawing all 88 keys wastes most of the screen on a piece that uses two octaves, and makes the keys too narrow to line up with the notes above them. Master Key analyses the score, snaps the range to white keys (black keys straddle the seam between two whites, so a black endpoint would leave a half key hanging off the edge), widens tiny exercises to a usable minimum, and pans smoothly between sections when a piece is genuinely too wide for one window — only ever at a rest, never mid-phrase.

Sheet music, in sync. If you supply the MusicXML alongside the MIDI, the real engraved score appears above the highway with the current bar highlighted and the sounding noteheads lit in the hand colours. The whole measure is highlighted rather than a thin cursor line, because losing your place happens at the bar level, not the note level.

Reading aids that are designed to be switched off. Note names, fingering, landmark notes, hand colouring and the keyboard mini-map are grouped under one dial that runs Max → Guided → Minimal → Off. The research is consistent that annotated notation helps beginners, but only when it is an explicit transitional scaffold — left on permanently it becomes a crutch. So it is arranged as a visible path towards reading unaided, and note names can fade as you improve.

Getting around a long piece. Drag anywhere on the falling notes to scroll the music past the key line, hearing it as it goes. A narrow strip down each edge does the same thing much faster: half the height of the pane is the whole song, so a single sweep gets from the first bar to the last without letting go.

Practice tools. Tempo from 25% to 125% with no pitch change, loop any bar or range, hands separate, count-in and metronome, and a tempo drill that alternates fast and slow rather than ramping monotonically upward — which is what the evidence actually supports.

Edit the notes by touch. Downloaded MIDI files are full of wrong notes, missing ties and passages nobody would play that way. Edit mode lets you fix them on the falling notes themselves: tap a note to select and hear it, drag its body to move it in time and pitch, drag either end to lengthen or shorten it, press and hold an empty lane to add one. Every drag sounds as it lands, so you hear the fix rather than only seeing it. A snap grid from 1/4 down to 1/32 — triplets included, or off entirely — decides how a note lands, pinch zooms the timeline in until a 1/32 is a comfortable target, and the nudge buttons move the selection by exactly one step or one semitone when a fingertip is not precise enough. Undo and redo throughout.

Turn on Select and a drag across empty space sweeps up everything it touches, so a whole passage can be moved, transposed an octave, reassigned to the other hand or deleted in one go — and taken back with one press of Undo. A hand you set by hand stays set, even on a song whose sheet music says otherwise.

The piece does not have to start where it starts: scroll up past bar 1 into the empty space in front of it and put a note there — drawn, dragged or nudged back out of the first bar — and the music shifts along to make room for the pickup or the introduction you wanted.

Saving rewrites the song's MIDI, so playback, the highway and the library all agree about what the notes are. The file you imported is kept, and Revert brings it back at any time — which matters, because a rewritten file carries the notes and nothing else: sustain pedal, other instruments and any text in the original are not preserved. The engraved sheet music also goes on showing the score you imported rather than your edits, and edit mode says so on screen.