Chord Randomizer vs MIDIRack
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Chord Randomizer
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Chord Randomizer is a powerful music theory practice tool from Nathaniel School of Music. Whether you're a beginner just learning your triads or an advanced musician drilling diatonic progressions, Chord Randomizer keeps your practice sessions fresh and effective. FEATURES - Randomised chord progressions so you never practice the same sequence twice - Three skill levels: Beginner, Intermediate, and Diatonic - Live audio playback with realistic instrument sounds: piano, guitar, harp, and cello - Arpeggio and block-chord playback modes, each with independent volume - Built-in metronome with configurable BPM from 40 to 240 - Playback speed multiplier: 1x, 1.5x, and 2x - Chord rate control: change chords every beat, every bar, or every two bars - Loop mode for continuous practice - MIDI export for use in any DAW - PNG export to share a clean chord chart with students or bandmates - Dark, professional UI optimised for practice sessions PERFECT FOR - Music students building chord recognition - Teachers generating practice exercises - Songwriters and composers exploring new progressions - Guitarists, pianists, and keyboardists of all levels Chord Randomizer runs entirely on-device. No account is needed, and no data is collected.
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.
Screenshots
Verdict
The clearest difference is price: Chord Randomizer at Free against MIDIRack's $14.99. Chord Randomizer also leads on in-app purchases (none vs 1) and iOS requirement (15.0 vs 17.0). On 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
Chord Randomizer is free to download; MIDIRack costs $14.99 up front. MIDIRack sells 1 one-off in-app purchase. Chord Randomizer asks for nothing beyond the download.
| Parameter | Chord Randomizer | MIDIRack |
|---|---|---|
| Price | Free — better | $14.99 |
| Rating | — | 4.8 (8 ratings) — better |
| Positive reviews | — | 66.7% of reviews |
| Number of ratings | — | 8 — better |
| Update frequency | — | Every 4 days |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | — | Free with in-app purchases |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 19 MB | 28 MB |
| Age rating | 4+ | 4+ |
| Developer | Jason Zachariah | Kai Aras |
In-app purchases
Chord Randomizer
No in-app purchases
MIDIRack
- Graph Editor Unlock$7.99





