C.ARP vs Pentatone
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
C.ARP
This app offers a unique approach to music creation, inspired by vintage instruments. It allows users to play chords and melodies with intuitive touch controls, apply real-time audio effects, and utilize a dynamic rhythm section. Advanced features include sampling, MIDI output via Bluetooth, and an iPad-optimized interface.
- Chord and melody playing
- Real-time audio effects
- Dynamic rhythm section
- Sampling and looping
- MIDI output via Bluetooth
- iPad optimized interface
- In-app tutorial
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C.ARP is a totally different keyboard. Inspired by old keyboards, omnichords and tape effects, it lets you play chords and melodies as well. Its design makes everything easier for a musician who just wants to play on mobile. Just hold on a button and then swipe or tap on the right section. But if you prefer, you can access chords and notes directly on the notes grid. Pitch them, harmonize, use mod wheel and apply real-time audio effects too. Rhythm section follows you every chord you choose: pick up the style you prefer, adjust BPMs, mute other instrument, change different midi settings, change drums and play them with drum pads. Do arpeggios with different sounds and rhythmic fractions, create different sound environments with delay, reverb and rotation. The design has also been updated for iPads, so you can enjoy the buttons and sections rearranged for the screen size. Record your voice or everything else as a sample, adjust its length, reverse or loop it, make chords and melodies with it and explore other cool features on this 4th version. There's also a tutorial inside! And finally: we added bluetooth out. It means you can connect your iPhone to your Mac and send midi notes right in your preferred DAW. Just follow the guide inside. Thanks to everyone who helped me: Giacomo, Virginia, Mattia, Andrea, Giulia, Cristiano, and the others. Thanks to the masters Suriani, Frankie and Calcutta. For every question or suggestion don't hesitate to write to me
Pentatone
This music app offers a unique pentatonic keyboard and built-in synthesizer, inspired by instruments like the kora and mbira. It features a sophisticated scale selection system and is optimized for touchscreen devices, providing an expressive and easy-to-play musical experience.
- Easy-to-play 'strummable' pentatonic keyboard
- 9 selectable pentatonic scales
- Custom FM synthesizer engine
- 25 preset sounds with macro controls
- Polyphonic touch and aftertouch response
- AUv3 functionality for host apps
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"Beautiful, fun and inspiringly expressive" - The Arithmophone Pentatone is a music app featuring an easy to play pentatonic keyboard and a built-in synthesizer. Instead of using piano keys or a grid-based interface, Pentatone takes a fresh approach, optimised for the ergonomics of touchscreen devices and inspired by instruments like the kora and mbira. The app also has a sophisticated scale selection system that includes all the common pentatonic scale types and unlocks some more unusual ones. Pentatone features: - An easy-to-play and 'strummable' keyboard, split for two handed playing - An original pentatonic scale system with 9 selectable scales, in just intonation or standard tuning - A custom synth engine (binaural 2x2 op FM with stereo detune, resonant filter, delay and reverb) - 25 preset sounds with macro sliders for tone and ambience - Initial touch and aftertouch response, both polyphonic - AUv3 functionality for use within host apps like GarageBand, Koala Sampler and Loopy Pro Pentatone user feedback: "Amazing! Love the simple UI and the musical keyboard. Also the sounds are lovely!" "This is very cool - beautiful interface and instantly musical." "This really is a joy to play and the tones are really expressive in fun ways that invite different types of creativity." "This app is such a brilliant idea!" "This is amazing. So fun to play. So easy to play with my daughter and my niece. The tones are wonderful." "This is an inspiringly expressive instrument! Really a joy to interact with." "This thing is AWESOME! It’s so easy to make up new stuff with it!" *** Pentatone is part of the Arithmophone project An Arithmophone is a thing that turns numbers into sounds, or math into music. Its name is derived from the ancient Greek words arithmos (number) and phone (sound). Any iPhone or iPad is itself an Arithmophone, because it routinely turns lists of binary numbers into sounds, for example when you use it to listen to music. But this app is a bit more 'arithmophonic' still, because it takes pure and simple harmonic ratios like 3:2 and 5:4 and uses these to build musical scales. You can use it as an easy-to-play instrument, a source of melodic and harmonic inspiration or a tool for learning about music and exploring the deep connection it has with numbers. Keep an eye out, future plans for the Arithmophone on iOS include: - PENTATONE JR., a simplified and text-free version of Pentatone, optimized for young/beginning musicians - DIATONE, the diatonic companion to Pentatone, featuring a 7-note-per-octave keyboard with all the familiar major and minor scales and modes - MIDI / MPE versions of Pentatone and Diatone - TONEHIVE, a microtonal keyboard synth for 7 limit just intonation - HUYGENS, a microtonal keyboard synth for 31 EDO To stay posted, join the community at reddit.com/r/arithmophone or subscribe to the Arithmophone youtube channel: https://www.youtube.com/@arithmophone
Screenshots
Verdict
The clearest difference is price: Pentatone at Free against C.ARP's $9.99. Pentatone also leads on rating (5.0 vs 4.3) and review sentiment (100% vs 74%). C.ARP's advantage is ratings volume (114 vs 13) and iOS requirement (13.0 vs 15.6). On update cadence, ads, in-app purchases 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
Pentatone is free to download; C.ARP costs $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Pentatone holds the better App Store score, 5.0 against 4.3. That said, the two scores are not equally well evidenced: C.ARP has 114 ratings behind it against 13, so its average is the more settled of the two. Written reviews point the same way: 74% of C.ARP's written reviews are positive against 100% of Pentatone's.
C.ARP ships an update every 4 weeks, Pentatone every 5 weeks. The most recent releases landed on September 22, 2026 and August 27, 2026 respectively.
| Parameter | C.ARP | Pentatone |
|---|---|---|
| Price | $9.99 | Free — better |
| Rating | 4.3 (114 ratings) | 5.0 (13 ratings) — better |
| Positive reviews | 74.3% of reviews | 100.0% of reviews — better |
| Number of ratings | 114 — better | 13 |
| Update frequency | Every 4 weeks — better | Every 5 weeks |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.0 — better | 15.6 |
| Further details — not scored | ||
| Size | 45 MB | 16 MB |
| Age rating | 4+ | 4+ |
| Developer | Paolo Giorgi | Chiel Zwinkels |
Customer experience
C.ARP
Pentatone
Bugs and requests
C.ARP
Reported bugs
40 issues- Sound doesn't work
- No sound
- App crashes when opening
- App crashes when trying to open
- App auto-quits on start
Show 35 moreShow fewer
- Chord panel smaller after update
- System setting always out
- App crashes after using only once
- App crashes when pressing a button
- MIDI Send is broken
- Can't open the app on Mac
- Can't close the menu
- App crashes if sample button is pressed
- Sample button crashes the app
- Strumming doesn't work
- App crashes when sample or reverse is pressed
- App is not stable / crashy
- Sampling function is DOA
- Sampler doesn't work / crashes
- Crash problem
- Send midi function greyed out
- App crashes when pressing the red sample button
- Sampler crashes the app 100%
- App crashes when attempting to use record feature
- Sample button keeps crashing the app
- Record, loop, or reverse buttons cause crash
- Bugs related to recording/sampling
- Sampler may crash
- Audio panel covers gear button
- E chord is extremely low octave and sounds muddled
- App crashes when trying to start an audio recording
- Certain audio glitches with recording and looping
- Buttons crash the app
- App crashes when pressing the sample button
- Sample and reverse buttons crash the app
- MIDI out doesn't seem to work
- Latency is a killer
- Chord doesn't trigger if not hit perfectly
- Sliding finger doesn't sound chord
- Sound can be tinny/harsh
Requested features
18 requests- Rearrange layout to be chromatic
- AUV3 support
- Inter-app-audio / GarageBand integration
- MIDI out functionality
- Save last state
Show 13 moreShow fewer
- Contextual help menus
- More sound design options
- Make it an Auv3 midi controller
- Support iPad
- Add "midi out" option
- Make it an audio app extension for GarageBand
- Add a way to use this app as a Bluetooth midi controller
- Add a visual distinction for individual buttons
- Add velocity on the strum bar
- Allow autoplay chord to hold like a drone
- Transpose reverb of strummed notes
- Add midi connectivity with external devices and other apps
- Add custom colors for themes
Pentatone
Not enough reviews yet to summarise bugs or requests.
In-app purchases
C.ARP
No in-app purchases
Pentatone
No in-app purchases





