MIDIRack vs Billie Tracker
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.
Billie Tracker
Create music with a powerful groovebox featuring a step sequencer, synthesizers, and a sampler. Arrange patterns into songs, shape unique sounds, and export your finished tracks. Designed for intuitive music production on mobile devices.
- Step sequencer for notes and instruments
- Shapeable synth instruments
- In-app sampler for recording sounds
- Mixer with per-track controls
- Song arrangement and export options
- Hardware controller support
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Billie Tracker is a groovebox: a step sequencer, synth instruments, a sampler and a mixer, built as one instrument for your phone or tablet. You write music in a grid. Notes go into patterns, patterns chain into sections, and sections line up into a song, so a full track grows out of small pieces you can reuse and rearrange. Trackers have worked this way for decades. If you have used one, this will feel like home. If you haven't, a built-in tutorial walks you through your first pattern, and every screen has help one key away. It is not tied to one sound. Shape the synths from clean tones to heavy drive, sample anything and play it back as an instrument, and make whatever you want to make: techno, ambient, hip hop, pop, or the 8-bit styles trackers are known for. Rows hold up to eight notes, not just one. Every instrument is polyphonic, so a chord goes into the grid the same way a single note does. Hold one on a MIDI keyboard and it lands across the row's note lanes, quantized and in key. What you get: - A step sequencer for notes, instruments, volume and effects, with chains and a song view for arrangement - Up to eight note lanes on every row, so chords are typed in like single notes, on any instrument - Synth instruments you can shape: timbre, color, filter, drive, envelopes and LFOs - A sampler that records straight into the app, so your own sounds sit next to the synths - A mixer with per-track levels and sends - BOUNCE and STEMS, so a finished song leaves the app as audio - Bundles: a song and every sample it uses travel as one file - A control surface built for tracker speed. Hold one key, press another, fast. Rearrange the layout to fit your hands, or plug in a hardware keyboard or game controller - Themes, KEY and SCALE settings, and a HELP key that explains whatever you are looking at Your songs are ordinary files. There is no account and nothing to sign into. Send a song to a friend, email one to yourself, or move it around in your file manager. Nothing is uploaded to us and nothing is locked to us. Billie Tracker is made by Billie Workers' Co-op. The people using it steer what gets built, and the Discord is the fastest way to reach us.
Screenshots
Verdict
The clearest difference is price: Billie Tracker at Free against MIDIRack's $7.99. Billie Tracker also leads on in-app purchases (none vs 1) and review sentiment (100% vs 67%). On ratings volume, update cadence, 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
Billie Tracker is free to download; MIDIRack costs $7.99 up front. MIDIRack sells 1 one-off in-app purchase. Billie Tracker asks for nothing beyond the download.
Billie Tracker holds the better App Store score, 5.0 against 4.8. Both are backed by a comparable volume of ratings — 10 and 5 respectively. Written reviews point the same way: 67% of MIDIRack's written reviews are positive against 100% of Billie Tracker's.
MIDIRack ships an update every 4 days, Billie Tracker every 2 days. Both last shipped on October 31, 2026.
| Parameter | MIDIRack | Billie Tracker |
|---|---|---|
| Price | $7.99 | Free — better |
| Rating | 4.8 (10 ratings) | 5.0 (5 ratings) — better |
| Positive reviews | 66.7% of reviews | 100.0% of reviews — better |
| Number of ratings | 10 — better | 5 |
| Update frequency | Every 4 days | Every 2 days — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 17.0 | 15.1 — better |
| Further details — not scored | ||
| Size | 28 MB | 57 MB |
| Age rating | 4+ | 4+ |
| Developer | Kai Aras | Billie Cooperative |
Customer experience
MIDIRack
Billie Tracker
In-app purchases
MIDIRack
- Graph Editor Unlock$7.99
Billie Tracker
No in-app purchases









