MIDIRack vs Porthole Audio
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
MIDIRack
Design custom MIDI control surfaces with a variety of instruments and sequencers. Unlock advanced features like a visual MIDI processing graph for complex routing and generative music creation. Use it standalone, as an AUv3 plugin, or to control desktop DAWs.
- Customizable touch surface design
- KB-1 keyboard suite with MPE support
- Advanced step and matrix sequencers
- Visual MIDI processing graph
- Built-in instruments and samplers
- Connects to desktop DAWs via USB or Bluetooth
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MIDIRack is a MIDI toolkit for iPad. Build a custom touch surface from the KB-1 keyboard suite, an all-new sequencer suite, knobs, faders, buttons and more — then unlock a visual MIDI processing graph (one time in-app purchase) and wire it into anything, from a simple custom controller to a full-on groovebox or a self-playing generative composer. Play it on its own and send MIDI anywhere, as an AUv3 plugin in your favourite host or a standalone instrument. THE BASE APP — PERFORMANCE SURFACE Design a custom control surface on a snapping grid: • The KB-1 keyboard suite — piano, diatonic chord pads, scale-locked keyboard, MPE Seaboard ribbon, MPE Strings grid (4ths), and a 4×4 GM drum-pad grid. Each is its own routable node with latch and octave shift. Successor to the KB-1 Expressive Keyboard Suite. • A suite of sequencers — drum, melody, chord, analog and CC step grids and a Matrix note grid, with a moving playhead, swing and microtiming. Per-step velocity, probability, tie and trigger conditions; pattern chaining and 4-pad scene switching for full arrangements; a knob-per-step analog machine that re-roots live as you play. • Knobs, faders, XY pads, buttons and live visualizers — bind to raw MIDI CC or graph parameters. On its own: a rich custom control surface builder — send MIDI and CC to any synth, app or hardware, no graph required. WITH YOUR DESKTOP DAW Expressive MPE hardware costs hundreds. MIDIRack turns the iPad you already own into a controller for Logic, Live, Bitwig, Cubase or any desktop DAW: • Two MPE surfaces — the Seaboard ribbon and the Strings grid send per-note pitch bend, slide and pressure to any MPE-capable instrument on your desk. • A controller that changes per track — MPE ribbon for the lead, drum pads for the beat, chord pads for the progression, faders mapped to CC for a mix move. Rearrange in seconds; save a surface per project. • Sequence it too — clock the step lanes to your DAW and drive its tracks. • Easy to connect — one USB cable to a Mac via IDAM (Inter-Device Audio and MIDI), or wirelessly over Bluetooth MIDI. No driver, no helper app. UNLOCK — MIDI GRAPH (in-app purchase) Wire MIDI In → processors → MIDI Out on a visual canvas: • 60+ node kinds — arpeggiators, scale/key quantizers, transposers, chords, echoes, swing, humanize, euclidean rhythms, random/generative melodies, LFOs, CC tools, an analog knob-per-step sequencer, a Matrix sequencer and a Counter. • Built-in instruments — Synth, Drums, a Sampler and a loop Slicer make sound right in the graph; no external synth required. • Emergence generators — Conway's Game of Life, Turing machine, Wolfram rules, Markov, bouncing balls, Lorenz attractor — for evolving, living patterns. • Presets — factory patches grouped by category (control surfaces, generators, keyboards, utilities): Amen Engine, Starfield, Conway Choir, Turing Bass, Cellular Drums… Save your own. ROUTING & MPE • MIDI Out exposes all 16 channels plus an MPE connector — multitimbral, multi-instrument setups. The built-in synth responds to MPE. • Every keyboard is its own node — process and route each one independently. PLAYS OUT OF THE BOX • Built-in polyphonic synth, drum kit, sampler & slicer or send MIDI to your gear via CoreMIDI and an always-on virtual port.
Porthole Audio
This app captures system audio from your device and routes it into audio plug-ins. It allows you to host AUv3 plug-ins and use the app itself as an instrument within other music applications.
- Capture system audio
- Route audio to plug-ins
- Host AUv3 plug-ins
- Use as an AUv3 instrument
- Cross-app audio capture
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Porthole captures audio from other apps and sends it directly to AUv3 samplers. No screen recordings, video trimming, or file transfers required. AUv3 Hosting Open a compatible sampler inside Porthole and capture audio directly into it. AUv3 Instrument Load Porthole in AUM, Loopy Pro, GarageBand, or another compatible host. Direct Audio Capture Record audio playing in other apps without creating video files or extracting audio afterward.
Screenshots
Verdict
The clearest difference is in-app purchases: Porthole Audio at none against MIDIRack's 1. Porthole Audio also leads on rating (5.0 vs 4.8) and price ($4.99 vs $7.99). MIDIRack's advantage is review sentiment (67% vs 50%) and update cadence (every 4 days vs every 11 days). On ratings volume, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
MIDIRack costs $7.99 and Porthole Audio $4.99 up front. MIDIRack sells 1 one-off in-app purchase. Porthole Audio asks for nothing beyond the download.
Porthole Audio holds the better App Store score, 5.0 against 4.8. Both are backed by a comparable volume of ratings — 9 and 4 respectively. Written reviews complicate that: 67% of MIDIRack's written reviews are positive against 50% of Porthole Audio's, so the app with the better star average is not the one people write more warmly about.
MIDIRack ships an update every 4 days, Porthole Audio every 11 days. The most recent releases landed on October 28, 2026 and October 26, 2026 respectively.
| Parameter | MIDIRack | Porthole Audio |
|---|---|---|
| Price | $7.99 | $4.99 — better |
| Rating | 4.8 (9 ratings) | 5.0 (4 ratings) — better |
| Positive reviews | 66.7% of reviews — better | 50.0% of reviews |
| Number of ratings | 9 — better | 4 |
| Update frequency | Every 4 days — better | Every 11 days |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases — better | Paid |
| Best chart rank | — | #177 — better |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.0 — better | 27.0 |
| Further details — not scored | ||
| Size | 28 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | Kai Aras | Feras Alnatsheh |
Customer experience
MIDIRack
Porthole Audio
In-app purchases
MIDIRack
- Graph Editor Unlock$7.99
Porthole Audio
No in-app purchases









