MIDIRack: Build Custom MIDI Surfaces & Graph on iPad

Numerical has released MIDIRack, a comprehensive MIDI toolkit for iPad. It combines the entire KB-1 Expressive Keyboard Suite with a full suite of sequencers and a customizable control surface. Moreover, it includes an optional visual MIDI graph editor for deep signal routing.

What Is MIDIRack?

MIDIRack is a standalone app and AUv3 plugin. It lets you place keyboards, sequencers, knobs, faders, XY pads, and buttons on a snapping grid. You can then bind these controls to MIDI CC and send data to any synth, app, or hardware via CoreMIDI. Additionally, built-in synth and drum sounds mean it works out of the box.

All six KB-1 keyboards are included: a velocity-sensitive piano, diatonic chord pads, a scale-locked keyboard, an MPE Seaboard ribbon, an MPE Strings grid, and a drum pad grid. Each keyboard is a routable node, allowing for complex signal paths.

Sequencers and Control Surface

The app offers tap-to-edit drum, melody, chord, analog, and CC step sequencers. You also get a Matrix note grid. Per-step velocity, probability, tie, trigger conditions, and microtiming provide deep control. Pattern chaining and a four-pad scene launcher make arranging easy.

For connectivity, MIDIRack works with Logic, Live, Bitwig, and Cubase over a single USB cable or Bluetooth MIDI. The two MPE surfaces respond with per-note pitch bend, slide, and pressure. The layout can be rearranged and saved per project.

Graph Editor Unlock

An optional one-time purchase adds a visual MIDI graph editor. This allows you to wire MIDI In through processors to MIDI Out using 60+ node types. These include arpeggiators, quantizers, Euclidean generators, LFOs, and generative nodes like Game of Life and Turing machines. Instrument nodes such as Synth, Drums, Sampler, and Slicer are also included.

Every keyboard on the surface becomes a node in the graph. Furthermore, surface knobs can bind to graph parameters. For instance, an LFO modulating a patch will physically move a knob on the surface. Factory graph patches run for free; editing and saving require the unlock.

Features

Six touch keyboards, including MPE surfaces
Step, chord, analog, CC, and matrix sequencers
Customizable control surface with knobs, faders, XY pads
Visual MIDI graph editor (unlock) with 60+ nodes
Built-in polyphonic synth and GM drum kit
Supports AUv3 and standalone use
Runs as MIDI processor or generator
CoreMIDI out and always-on virtual port
Pattern chaining and scene launcher
Per-step probability, microtiming, trigger conditions

Pricing and Availability

MIDIRack is available now on the App Store for iPad (iPadOS 18 or later). The base app costs $7.99 at launch (regular $14.99). The Graph Editor unlock is also $7.99 at launch (regular $14.99). This introductory pricing lasts through August 31, 2026. There is no subscription; both are one-time purchases.

iPhone and Mac (Apple silicon) versions are in development. Overall, MIDIRack offers a flexible, powerful MIDI toolkit for iPad producers.