midi vs Octal
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
midi
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midi-sink models a tray of water with ink floating on it. Every gesture is an exact, area-preserving transformation of the whole sheet — Aubrey Jaffer's mathematical marbling — so the rings stay crisp after a thousand strokes. Two modes. MARBLE MODE is the tray under your hands: tap for a drop, drag to comb, twist two fingers for a vortex, pinch to fold, draw with the Pencil and a wake follows the tip. Plug in a MIDI instrument and it plays into the same water: an MPE controller's strike, pressure, glide and slide become drop, feed, comb and hue; a wind controller draws a single calligraphic line; any keyboard plays drops on the circle of fifths. PLAY MODE turns the iPad into an MPE instrument. A pitch lattice — chromatic grid, Jankó or piano grid — sits under your fingers; every touch is a joystick (sideways bends in semitones, push to feed ink, pull back to stir). The Apple Pencil plays legato across the keys with real force as velocity, its barrel roll deepens vibrato and the Pencil Pro's squeeze is the sustain pedal. A floating strip carries pitch, mod, two assignable wheels and sustain on the MPE master channel. The stream goes out over a virtual CoreMIDI source (also to a USB-tethered Mac), the MIDI network session and Bluetooth LE MIDI, so any DAW or synth records a standard MPE performance while the water paints it. Made for MPE controllers — ROLI Piano and Seaboard, Expressive E Osmose — the ROLI Airwave's gesture CCs, wind controllers (Roland Aerophone, Odisei Travel Sax) and classic keyboards. midi-sink makes no sound of its own: it is a visualizer and a controller. Free software (AGPL-3.0). Collects nothing.
Octal
This app transforms your phone into a musical instrument with eight intuitive buttons that always create harmonious chords or notes. Easily record loops, layer beats, and arrange them into full songs. Explore a variety of sounds and share your creations.
- Eight-button chord/note interface
- Loop recording and editing
- Song arrangement
- Diverse sound library
- Undo/history functionality
- Audio file sharing
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Octal turns your phone into an instrument. The eight buttons play chords or notes that always go together, so whatever you press sounds like music. The bead under your other thumb changes their mood or behavior as you play. MAKE A LOOP Press record and play a few bars. Open the wheel, pick drums or a bass, and play over the top. Swipe over to the Loop Deck to see your loop and change it bar by bar. TURN LOOPS INTO A SONG Pinch the Loop Deck and chain your loops into a song. SOUNDS Synths, keys, drum kits, textures and acoustic instruments, a tap away on the wheel. NEVER LOSE AN EDIT Every edit is kept. The history tool lets you wind back to any of them. SHARE IT Send the mix as an audio file, or send the loop or song itself to a friend who has Octal. Making music in Octal is free, with four saved loops and one song. THE FULL VERSION One purchase, no subscription. MIDI and stems to finish your song in a DAW, MIDI out to play other synths, the bead lab to make and keep sounds of your own, and as many loops and songs as you like. PRIVACY Octal collects no data. The microphone is only on while you record a sound or play a Vocoder.
Screenshots
Verdict
The clearest difference is in-app purchases: midi at none against Octal's 1. midi also leads on iOS requirement (16.0 vs 26.0). Octal's advantage is update cadence (daily vs every 5 weeks). On price, 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
Both are free to download. Octal sells 1 one-off in-app purchase. midi asks for nothing beyond the download.
midi ships an update every 5 weeks, Octal daily. Both last shipped on October 29, 2026.
| Parameter | midi | Octal |
|---|---|---|
| Price | Free | Free |
| Rating | — | 5.0 (2 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 2 — better |
| Update frequency | Every 5 weeks | Daily — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | — | Free with in-app purchases |
| Devices | iPhone, iPad — better | iPhone |
| Requires iOS | 16.0 — better | 26.0 |
| Further details — not scored | ||
| Size | 8 MB | 36 MB |
| Age rating | 4+ | 4+ |
| Developer | Vibetuned | RYAN JAMES,GALANG ELLIS |
In-app purchases
midi
No in-app purchases
Octal
- Octal, the full version$9.99








