Roostbox vs Grasswhistle
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Roostbox
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Roostbox is a groovebox that looks like a retro arcade cabinet and plays like one. It makes techno and other electronic music live, by hand: fly a ship through a beat, ride the faders, flick the stick, and every gesture you make is recorded and loops with the beat. It is a different way to play electronic music live. There is no step grid to program and no timeline to edit. Everything on screen is a control, you play it with two thumbs, and the loop keeps what you played. Two kits are in the box, and everything is free: both kits, the whole performance surface and the AUv3 plugin. No purchase, no account, no ads. Play it standalone on iPhone or iPad, or load it as an instrument inside AUM, Loopy Pro, Cubasis, Drambo or Logic Pro for iPad. TWO KITS IN THE BOX SPACE: fly a ship through a beat. Where the ship goes picks the groove: four-on-the-floor, backbeat, offbeat, broken, sixteenths. The cockpit page holds the mixer, a stick for filter and grit, overdrive, pump, tape, delay, reverb, crush and a DJ filter. A 303-style acid bass and a drum synth make the sound. PLIVKA: a four-track techno box. Kick, bass, snare and hat, each with a pattern control and a hit control, laid out over five pages: Rhythm, Sound, Perform, FX and Mix. The bass line is a Turing machine that mutates as much or as little as you let it. UNDER THE HOOD - Euclidean rhythm generators, a Turing machine sequencer and a trigger sequencer drive the patterns. - A drum synth and a 303-style acid bass synth make the sound. No samples. - Every fader move is recorded as motion and loops with the beat. Undo and redo if you change your mind. - Scenes: snapshot the whole kit and switch on the next sixteenth, beat, bar or pattern. - Master effects: delay and reverb sends, filter, crush, tape, compressor, sidechain pump and a limiter. - MIDI learn: map any control to a hardware controller. - Landscape only. Made for two thumbs. AUv3 The plugin is the same instrument as the app, with the same two kits, and it is free. It follows the host tempo and transport. Jam in the standalone app; record into your DAW with the plugin. WHAT 1.0 IS Two kits, built to be played. Building your own kits is not part of this version. Roostbox is made by one person. If something is broken, tell me: reach.freefall.studio@gmail.com
Grasswhistle
Create unique melodies from chord progressions with a customizable arpeggiator. Offers randomization, performance options, and over 50 presets. Use it as a standalone instrument or a MIDI effect to sequence other devices.
- Customizable arpeggios
- Chord progression sequencing
- Randomization features
- Performance options
- 50+ factory presets
- Standalone instrument
- MIDI effect
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Customizable arpeggios, right at your fingertips. Grasswhistle is a free arpeggiator from Aqeel Aadam Sound. Build a sequence of notes to arpeggiate your chord progressions in brand new ways. Grasswhistle adapts to whatever chord you throw at it, creating a seamless and recognizable melody from any chord progression. Find instant inspiration with robust randomization features, performance options, and 50+ factory presets. Grasswhistle can be loaded as an instrument or as a MIDI effect. As an instrument, it has a built-in synth voice for quick and easy playback. As a MIDI effect, you can sequence your favorite devices with endlessly inspiring arpeggios. Grasswhistle is completely free, though you can choose to send a tip inside of the standalone app. This is completely optional, but always appreciated! This donation does not unlock any additional functionality. Also available for macOS and Windows in VST3 / AU / AAX formats from Aqeel Aadam Sound.
Screenshots
Verdict
The clearest difference is rating: Grasswhistle at 5.0 against Roostbox's 4.5. Grasswhistle also leads on update cadence (every 2 days vs every 3 weeks). Roostbox's advantage is in-app purchases (none vs 2). On price, review sentiment, ratings volume and ads 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. Grasswhistle sells 2 one-off in-app purchases. Roostbox asks for nothing beyond the download.
Grasswhistle holds the better App Store score, 5.0 against 4.5. Both are backed by a comparable volume of ratings — 2 and 3 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
Roostbox ships an update every 3 weeks, Grasswhistle every 2 days. The most recent releases landed on November 13, 2026 and November 15, 2026 respectively.
| Parameter | Roostbox | Grasswhistle |
|---|---|---|
| Price | Free | Free |
| Rating | 4.5 (2 ratings) | 5.0 (3 ratings) — better |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 2 | 3 — better |
| Update frequency | Every 3 weeks | Every 2 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | — | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.0 | 13.0 |
| Further details — not scored | ||
| Size | 71 MB | 18 MB |
| Age rating | 4+ | 4+ |
| Developer | ARTEM VOVSIA | Aqeel Aadam |
Customer experience
Roostbox
Grasswhistle
In-app purchases
Roostbox
No in-app purchases
Grasswhistle
- Small coffee$3.00
- Large coffee$5.00





