macOS · Live performance
The MIDI brain between you and your rig.
Secondo is a live-performance MIDI processor and Audio Unit host for macOS. It sits between you, your controller, and your sound sources — adding splits, chord mirroring, automatic sustain, harmonies, and performance macros in real time.
The stage surface — splits, layers, and macros programmed per song.
Features
Programmable musical behavior, live.
Hand splits
Split the keybed anywhere. Each zone gets its own sound, octave, and behavior — pads left, lead right, and the split moves per song.
Chord mirroring
Play a chord with one hand and Secondo mirrors it where you need it — full voicings from a single grip while the other hand stays free.
Automatic sustain
Sustain that follows your playing instead of your foot. Zones can hold pads underneath while runs on top stay clean.
Harmonization
Add harmony lines in real time — intervals and voicings applied to what you play, per zone, without a second keyboardist.
Routing & AU hosting
Secondo hosts your Audio Units and routes every zone to the right instrument or hardware. One controller, a whole rig behind it.
Performance macros
One press reshapes the rig mid-song: swap splits, layers, and sounds together, built into setlists so every song loads ready.
How it works
Between the controller and the sound.
Plug in
Connect your MIDI controller to your Mac. Secondo sits in the middle — between the keys and everything that makes sound.
Program the behavior
Set splits, layers, mirroring, sustain, harmonies, and macros per song, and line the songs up in a setlist.
Play
On stage, Secondo shapes every note on its way to your Audio Units and hardware. Next song, next preset — one press.
About
Built for the stage, not the studio.
Most MIDI tools are built for producers at a desk. Secondo is built for the moment the count-in ends: a native macOS app whose engine — written in Rust — owns the MIDI path, Audio Unit hosting, setlists, and performance state, with a stage surface designed to be operated mid-song.
It grew out of a working live rig, and every feature earns its place the same way: by surviving a real set.
Native macOS
A real Mac app — no plugin chain gymnastics, no laptop-in-a-browser.
Rust engine
The performance path — routing, hosting, state — lives in Rust.
Setlists first
Songs, presets, and macros organized the way a gig actually runs.
Operator-facing UI
A stage surface you can read and work between phrases.
Secondo is in development.
Leave your email and hear about it once — when it's ready.