Holon vs Fluss
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Holon
This app transforms your movement through cities into a dynamic, real-time musical score. It uses your physical location and activity to generate interactive synth music, encouraging outdoor exploration and turning listeners into performers.
- Human-powered music generation
- Encourages outdoor activity
- Zero UI for minimal distraction
- Environmentally responsive music
- Real-time synth music creation
- Optional AirPods and Apple Watch integration
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Holon makes the city your instrument. It turns your movement in the environment into a synthetic, interactive score that reflects your context, supports your activities and alerts you to changes in the surrounding area. Holon uses physical computing and a geospatial dataset to synthesize music on the iPhone in real time from your data - no streaming or AI involved, just pure DSP and logic. What Holon Does: * Human powered music. Every action generates dynamic, improvised synth music in real time. * Encourages outdoor activities. Holon doesn’t work in your apartment or by shaking your phone around. Move through streets, parks, and transit systems to make the music happen. * Stays out of your way. Zero UI means less screen time, no distractions. * Uses places and spaces to modify the music you make. The environment isn’t background - it’s the score. * The more and further you move, the more things happen in the music. Use your musical agency instead of skipping and swiping. Why Holon Exists: Music has been reduced to a commodity and a background activity for consumerism. Holon isn’t here to help you chill when you swipe, scroll and buy more stuff, or improve your focus when working for the Man. Holon is here to break away from the static, one-way relationship of streaming services and to put the human in the loop - yourself. Forget emoting celebrities with their false sincerity, throw overproduced passive soundscapes and statistical algorithms on the dung heap of history. Holon turns listeners into performers and unlocks the musical potential of places. How to Use: * Go outside - Holon needs space to function, just like you. Different districts, parks, bridges, shops, street furniture - all contribute to the musical output. Strolling around your apartment or shaking your phone won’t do. * Put the phone in your pocket or on your dashboard. * Walk, run, drive - the world is now the interface, space is the machine. * Use the big button in the middle to power Holon off when not in use - Auditory AR can be a battery-intensive process! * Optional Apple AirPods support for head-controlled musical interactions! * Optional Apple Watch support for heart rate-synced music (biofeedback) *the Watch app may take a moment to install* Requirements: * Available in over 1000 regions in more than 100 countries. * Check coverage or request a new area at holonic.systems/holon. * Best experienced with headphones. Ensure adequate battery level for extended use. * A data plan is required to access our geospatial engine but use of data is low. Holon: Become part of the circuit and… Become Sound™
Fluss
Explore granular synthesis with a tactile interface. Import, record, or live-process audio to create unique sound textures, drones, and echoes. Features kinetic sliders for dynamic modulation and a unique shimmer feedback effect.
- Granular synthesis engine
- Import, record, or live process audio
- Kinetic sliders for modulation
- Shimmer feedback effect
- MIDI playable
- Oberheim Xpander inspired filter
- Microtonal experiment support
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Fluss is a sonic playground designed by Bram Bos and Berlin-based musician Hainbach to let you explore granular synthesis in a hands-on way. The playful touch UI invites anything from live performance, experimentation to learning and mastering the granular concept. Multiple plugins: Import, Record or Live Process You can import your own WAVs (standalone & AUv3 Instrument plugin), Record audio (Record effect plugin) or live-process sound (Process effect plugin) to create anything from drones and granular echoes to moving microtonal audio textures. Designed for touch: Kinetic Sliders All sliders and XY pads are linked to a physics model which lets you flick and throw them around. Minimise the friction for endless bouncing motion, as an innovative substitute for traditional LFOs and modulation. There was never a better reason for using a touchscreen for music. Shimmer Feedback effect Like a shimmer reverb, except it feeds the processed audio back into the grain engine. This lets you create an endless loop of pitch-shifting spaciousness, turning even the simplest of sounds into massive woolly mammoths. - 3 Voice grain engine, each with an independent playhead - Playable via MIDI (since version 1.1) - Filter inspired by the Oberheim Xpander, including its resonant Phase filter - Kinetic sliders and pads for playful interaction with the sound - Universal design (iPhone and iPad; iPad Air 2 or higher recommended) - Custom scales, unquantised mode and even Scala-import for microtonal experiments - Use WAVs (or other audio files), record audio or load the app as a live-processing audio effect - Real world tested as an instrument in numerous live performances by Hainbach - Offers light mode and dark mode UI
Screenshots
Verdict
The clearest difference is price: Holon at Free against Fluss's $13.99. Fluss's advantage is in-app purchases (none vs 2) and rating (4.8 vs 4.5). On review sentiment, update cadence, ads and monetization model 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
Holon is free to download; Fluss costs $13.99 up front. Holon sells 2 one-off in-app purchases. Fluss asks for nothing beyond the download.
Fluss holds the better App Store score, 4.8 against 4.5. That said, the two scores are not equally well evidenced: Fluss has 72 ratings behind it against 14, so its average is the more settled of the two. Written reviews point the same way: 75% of Holon's written reviews are positive against 78% of Fluss's.
Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on November 2, 2026 and November 7, 2026 respectively.
| Parameter | Holon | Fluss |
|---|---|---|
| Price | Free — better | $13.99 |
| Rating | 4.5 (14 ratings) | 4.8 (72 ratings) — better |
| Positive reviews | 75.0% of reviews | 78.0% of reviews — better |
| Number of ratings | 14 | 72 — better |
| Update frequency | Every 3 months | Every 3 months |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod, Apple Watch — better | iPhone, iPad, iPod |
| Requires iOS | 12.0 | 12 |
| Further details — not scored | ||
| Size | 144 MB | 453 MB |
| Age rating | 4+ | 4+ |
| Developer | Holonic Systems Oy | Bram Bos |
Customer experience
Holon
Fluss
Bugs and requests
Holon
Not enough reviews yet to summarise bugs or requests.
Fluss
Reported bugs
4 issues- Crashes with black screen
- No audible output
- App resets when put in background
- Cyan play head difficult to see on waveform
Requested features
20 requests- Adjustable layer field per grain
- Record from internal microphone
- More control over grain direction
- BPM settings
- Transition from clean to new sounds
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- AUv3 plugin version
- Scan speed multiplier (x2, x4)
- Draw lines on pitch XY pad
- Lock oscillators on pitch XY pad
- Assign play heads triggered by external controller
- Snapshots for pitch section
- More clock and tempo syncing options
- Visualization of buffer, playback head speed, modulation
- Quantizer visualization
- User-changeable pitch XY pad layout
- Global friction and separate sensitivity option
- Modulation to specific play head
- Proper sampling button (microphone access)
- Preset browser arrows
- More control over panning, filter, scan speed
In-app purchases
Holon
- Apple Watch supportFree
- Movesense SupportFree
Fluss
No in-app purchases









