C.ARP vs Operabook
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
Operabook
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Operabook is the industry’s reference tool for opera professionals worldwide, representing 75,000+ artists performing in 60,000 productions in 600+ companies, festivals and competitions, brought to you by Opera Europa and Opera America. 15 YEARS OF COMPREHENSIVE ARCHIVES Productions: seasons, casts, dates, venues Artists: careers, collaborations Roles: complete repertoire by voice type and specialty International coverage: Europe, Americas, Asia APP FOR CASTING PROFESSIONALS Interface optimised for on-the-go consultation of artists performance data ADVANCED SEARCH ON THE WEBSITE Sophisticated multi-criteria filters Search by artist, roles Artistic collaboration history Career analysis and cast evolution tracking Collaborative tools for production rentals and co-productions Developed by and for opera professionals, this application centralizes the scattered information of the global opera industry. Save valuable time in your casting research, programming, and creating new collaborations. Professional authentication required.
Screenshots
Verdict
The clearest difference is price: Operabook at Free against C.ARP's $9.99. C.ARP's advantage is update cadence (monthly vs every 5 months) and chart position (#101 vs unranked). On ads, in-app purchases, device support and iOS requirement 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
Operabook is free to download; C.ARP costs $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.
C.ARP ships an update monthly, Operabook every 5 months. The most recent releases landed on October 12, 2026 and October 6, 2026 respectively.
| Parameter | C.ARP | Operabook |
|---|---|---|
| Price | $9.99 | Free — better |
| Rating | 4.3 (114 ratings) — better | — |
| Positive reviews | 74.6% of reviews | — |
| Number of ratings | 114 — better | — |
| Update frequency | Monthly — better | Every 5 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Best chart rank | #101 — better | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 — better | 15.1 |
| Further details — not scored | ||
| Size | 46 MB | 29 MB |
| Age rating | 4+ | 4+ |
| Developer | Paolo Giorgi | IT4Culture |
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
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- 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
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- 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
Operabook
Not enough reviews yet to summarise bugs or requests.
In-app purchases
C.ARP
No in-app purchases
Operabook
No in-app purchases









