Two clocks, on purpose

The piece and the groove run on separate clocks. The piece streams at its own speed — slow Satie stays slow — while the drums, bass and your loop run at a groove tempo you set in BPM. The ⇄ Sync button guesses a sensible groove from the piece's pulse; the sliders are yours from there. Layers land on the groove's bar line, so nothing you press can be early or late.

Play on top, keep the loop

The keyboard at the bottom is a performance instrument: mouse or the A–L letter rows, octave up and down on Z/X, and scale lock snaps every note into the detected key so jamming over the piece cannot go wrong. Hit ⏺ Rec and everything you play is captured into a 1, 2, 4 or 8-bar loop — quantized to the sixteenth if you like — and cycles until you clear it. Overdub by recording again on top. Loops are stored in groove time: change the BPM later and your loop keeps its shape.

A groovebox that reads music

Every pad instrument on the web plays canned loops — a fixed key, a fixed tempo, someone else's music. This one is different because it can read. Load any piece from the library and the pad analyses the actual notation: the pulse comes from the piece's own grid, the key from a pitch-class profile of its notes, and the bass figures are pitched, bar by bar, from the piece's own bass line. Launch a layer and it follows the harmony wherever the music goes.

Everything you press is quantized to the next bar — the groovebox promise: you cannot be early, you cannot be late, you can only make it groove. The tempo slider reschedules the notes rather than stretching audio, so 50% and 200% are both artifact-free. Swing pushes every off-beat late, like a human would.

The rows

Drums — a full 4×16 step matrix you edit live, with four classic grooves as starting points. Bass — root pulse, octave pump, fifth walk and a bass arp, all pitched from the bar you are actually in. Texture — chords and arpeggios from each bar's own harmony, a shimmer that echoes the melody an octave up, and a drone on the detected key. Perform — momentary tricks: stutter, tape-stop, a riser that peaks on the next bar line, and a one-bar break. Scenes A–D snapshot the whole machine — matrix, layers, mixer, both tempos — and recall on the bar, so a performance is scene changes, not menu diving. The mixer gives every voice its own level.

The key readout says what the analysis heard — it can be wrong on chromatic music, and it says so honestly rather than hiding. When you find a combination you love, learn the piece for real: every melody here lives in the letter-notes library, and the Flow Piano will let you play it with zero wrong notes today.