You open a .mid file right here in your browser and it becomes sheet music moving across the screen. Pick the tempo — anywhere from 30 to 160 beats per minute — and play along, reading the melody as it goes by. Then open the chords and plant them where they belong: bar by bar, half bar or beat by beat. And the song stays: every file you import lands in My songs, and one tap reopens the piece with its chords, just as you left it. Nothing is uploaded anywhere — it all happens inside your browser, and the file never leaves your device.
This is not a converter. No PDF comes out, no MusicXML, and there is no way to edit or print the score. And the chords are yours: you choose every one of them — the app does not guess the harmony in the file.
Sheet music from a book, moving on screen
Paper does not move. To read a piece at the tempo it is actually played, with the timeline sliding under your eyes, paper cannot help: you are the one who decides when the page turns. A MIDI file is the route that exists for carrying a piece that sits still into a format that moves — and that is what this screen does with whatever file you bring. To try it first with a piece that is already here, the read-and-play sheet music game comes with one.
MIDI does not carry the chords — that is why you plant them
A MIDI file records which note sounded, when, and for how long. It does not record the clef, it does not record the key signature and it does not record the chord symbols: the chord written above the staff in the book does not survive the crossing. Planting a chord, then, is not arranging anything — it is putting back what the format lost on the way. And what ends up on screen, melody below and chord above, is what the world calls a lead sheet.
There are three modes, and the third one exists because of the chords. In Practice, the score stops at every note and waits for you to play the right one. In time, it runs with a metronome and measures your playing — the right notes, and how precisely you attack each one. In Play along, it scrolls in time and measures nothing: that is the mode for someone playing the harmony, which is made of notes the melody never wrote down. You answer on the on-screen piano, on your computer keyboard, on a MIDI keyboard connected to your computer, or by playing into your microphone.
The list is called My songs and it belongs to this device: it holds 60. When it fills up the piece still plays — the screen tells you it did not fit, and nothing old is deleted to make room. Deleting a song from the list does not delete its chords either: identity is the content of the file, not its name, so importing the same .mid again brings the chart back. To carry your repertoire from the computer to your phone, you can export everything — files and chords — into a single file; importing on the other side adds to what is already there, without deleting anything. Saving is local, like the reading: nothing is uploaded to any server, and clearing the site data in your browser takes the songs with it. That is what the export is for.
The file goes through a gate before it becomes a score. Anything that does not fit a grid of note values is refused, with the reason written on the screen, rather than being drawn crooked: a live recording, carrying the human timing of whoever played it, is not a score, and tuplets are left out. The limit is 512 KB per file. And the reading is a single line: where the file has a chord, the top note is the one that goes in. It runs right in your browser, on a computer, tablet or phone, with nothing to install.