CZ App for iPad vs ButterSynth
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
CZ App for iPad
This music app recreates the functionality of classic Casio CZ-series synthesizers, offering a 4-part PD sound source with 36 waveforms for diverse sound creation. It allows users to play along with audio files, utilize multi-play modes for collaborative performance, and connect with external MIDI instruments.
- Phase Distortion (PD) sound source
- 36 waveforms for diverse sounds
- Play along to audio files
- Multi-play mode for collaborative performance
- External MIDI instrument support
- Inter-App Audio and Audiobus compatibility
Read full descriptionHide full description
【Recommended model】iPad mini 3、iPad Air、iPad Air 2 This app reproduces the functionality of Casio’s best-selling CZ-series models, such as the CZ-101 (first released in 1984), and also includes new functions. Featuring a built-in 4-part PD (phase distortion) sound source, its 36 waveforms are capable of generating an extensive and diverse range of sounds. The created tones can also be played on MIDI-compatible instruments. ======The PD sound source system======== Phase Distortion (PD) works by distorting a sine wave when it is read so that various different waveforms are produced.At the time, it was a ground-breaking system for generating waveforms other than simple sine waves. In the CZ series, 8 basic waveforms were generated by the PD sound source, with pairs of those 8 waveforms cascaded to provide a total of 33 waveforms. ----- An extensive parameter set to allow richly varied sound creation ----- Two block configuration systems are provided for each of the DCO, DCW and DCA ・ WAVE FORM (DCO1/DCO2) Parameters to set basic waveforms. 8 basic waveforms can be selected for each of the 2 sound sources. You can play with a wide range of sounds based on eight basic waveforms and 28 combinations of those basic waveforms—for a total of 36 types of waveforms. ・ KEY FOLLOW One Key Follow feature (DCW1/DCW2) controls waveforms based on the upper and lower extent of the keyboard's register while the other Key Follow feature (DCA1/DCA2) controls the envelope duration based on the keyboard's register. ・ DETUNE/LINE SELECT CZ-series synthesizers allowed users to choose from 4 types of line output (1, 2, 1+2 or 1+1) depending on the purpose. Using 2 DCOs allowed the use of detuning to fine-tune the pitch shift in the two systems to within ±4 octaves, which is useful not only in creating a chorus effect, but also for producing sounds with specific harmonics emphasized. ・ RING/NOISE MODULATION Ring modulation can be used to produce metallic tones that include non-integer harmonics, while noise modulation is effective in creating percussion-like sounds. ・ ENVELOPE GENERATOR An envelope generator is provided for each DCO, DCW and DCA core block in the two systems, which makes it possible to vary the tuning, tones and volume over time. -----Play along to your favorite audio files----- You can use the keyboard to play along to audio files on an iPad. -----Multi-play mode combines keyboard layouts to allow new ways of playing The new performance interface lets you can combine 2, 3 or 4 keyboards, or even flip the layout so that other people can play along with you. -----MIDI Player----- It is possible to play by reading the SMF. The maximum number of MIDI channels is 4. -----Supports external MIDI instruments and inter-app collaboration----- ・Inter-App Audio (iOS 7 or later) ・Audiobus compatible (input only) ・Playable using an external MIDI keyboard(via a third-party MIDI interface, an Apple Lightning-USB camera adapter* plus USB cable, or the Apple iPad Camera Connection Kit* plus USB cable) ・Virtual MIDI ・MIDI over Bluetooth
ButterSynth
This powerful synthesizer app offers a hybrid approach, combining wavetable, FM, and sample-based synthesis. Create unique sounds with a vast sonic range, advanced modulation, and a built-in effects rack. It caters to both experienced sound designers and beginners with extensive presets.
- Hybrid 6-oscillator synthesis (wavetable, FM, sample)
- Built-in wavetable editor
- FM engine with 4 operators
- Sample and Granulator engines
- 32-slot modulation matrix
- Internal FX rack with 16 modules
- Extensive preset library
Read full descriptionHide full description
ButterSynth is a hybrid 6-oscillator wavetable/FM/sample-based AUV3 and standalone synthesizer with a vast sonic range, from gentle pads to screaming leads and basslines. Mix any combination of wavetable, FM, sample and other synthesis engines for one truly massive sound. For the more advanced users, you'll love using ButterSynth's thoughtfully designed interface, incredibly powerful modulation matrix, fully-featured internal FX rack, factory waveform and sample libraries, and almost limitless scope for fun, experimentation and sound design. For less experienced synth programmers, ButterSynth includes a library of hundreds of ready-to-use presets, sparking your creativity to start making music right away. Headline features include - Mix and match any combination of 6 synthesis engines to either emulate your favourite synths of yester-year or build a synth ready for the future. - Dual-wavetable engines also feature 9 phase modes, wave folding, and deep unison controls modelled on vintage hardware synths. - Built-in wavetable editor gives you the ability to tweak, morph, and hand-draw your own custom wavetables, with each wavetable supporting up to 256 frames. - FM engine offers 4 operators with a selection of 12 modulation paths. Each operator can be loaded with any waveform from the factory or user library, and can also self-modulate via the feedback dial. - Sample and Granulator engines both let you load samples (either imported or from the factory library) and control precisely how they are chopped, triggered and layered. Both also feature the same powerful unison modes available in the WT engine. - Highly configurable 32-slot modulation matrix featuring precise mix/max ranges, self-modulation (via the amount target), plus configurable response curves and layer modes. Simply long-tap any parameter to set it as a Mod destination! - Full suite of versatile control sources which includes: 4x MSEG-style looping curve envelopes, 4x LFOs, 4x step sequencers, X/Y pad with motion recording, 8x Macro dials and a powerful arpeggiator inspired by Kirnu Interactive’s Cream. - The EFX rack lets you build your own insert effects chain using any combination of the 16 built-in FX modules. Modules available at launch include delay, reverb, distortion, chorus, OTT compression etc. Note - FX parameters can also be targeted by the mod matrix, unlocking the possibility to program ‘per voice’ modulated effects. - All presets, wavetables, samples and other settings are stored in the Files app, making bulk import/export, backup and community sharing quick and easy. - All of this is housed in an irresistibly designed 4-tab UI that makes synth programming quick and fun.
Screenshots
Verdict
The clearest difference is review sentiment: ButterSynth at 59% against CZ App for iPad's 35%. ButterSynth also leads on rating (4.0 vs 3.8) and ratings volume (63 vs 8). CZ App for iPad's advantage is price ($14.99 vs $19.99) and iOS requirement (8.0 vs 14.0). 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
CZ App for iPad costs $14.99 and ButterSynth $19.99 up front. Neither carries in-app purchases, so what you see is what you pay.
ButterSynth holds the better App Store score, 4.0 against 3.8. That said, the two scores are not equally well evidenced: ButterSynth has 63 ratings behind it against 8, so its average is the more settled of the two. Written reviews point the same way: 35% of CZ App for iPad's written reviews are positive against 59% of ButterSynth's.
Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on November 5, 2026 and November 11, 2026 respectively.
| Parameter | CZ App for iPad | ButterSynth |
|---|---|---|
| Price | $14.99 — better | $19.99 |
| Rating | 3.8 (8 ratings) | 4.0 (63 ratings) — better |
| Positive reviews | 34.8% of reviews | 59.2% of reviews — better |
| Number of ratings | 8 | 63 — better |
| Update frequency | Every 2 months | Every 2 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPad | iPhone, iPad, iPod — better |
| Requires iOS | 8.0 — better | 14.0 |
| Further details — not scored | ||
| Size | 33 MB | 468 MB |
| Age rating | 4+ | 4+ |
| Developer | CASIO COMPUTER CO., LTD. | Arto Vaarala |
Customer experience
CZ App for iPad
ButterSynth
Bugs and requests
CZ App for iPad
Not enough reviews yet to summarise bugs or requests.
ButterSynth
Reported bugs
39 issues- App crashing with AUM
- Disappears in Cubasis randomly
- Crashes all the time inside Logic
- Changing a patch spikes CPU to 99%
- Crashes on every patch change
Show 34 moreShow fewer
- No audio when rendering or freezing track
- Keyboard doesn't load on iPhone
- iOS18 broke ButterSynth (audio recording issues)
- Failed to load as Auv3
- Crashes as soon as a preset is selected
- Some patches hanging/sounding without input
- CPU spikes to 100% on preset switching
- Audio crackles on preset switching
- Sample module has consistent buzz
- LFOs are extremely simple (no phase offset)
- Square wave LFO is not square (has slew)
- Step sequencer always has glide/slew
- Cannot save custom presets
- No undo function in wave table editor
- AUv3 plugin resets when ButterSynth crashes
- Does not show up as auv3 in Cubasis, AUM, or Audio Evolution
- Crashes regularly even on newest iPad
- Preset changes every time play is pressed
- Not resizing appropriately on smaller screens
- Crashes with unison function in AUM
- White noise on crash with unison
- Sound continues after song stops in GarageBand
- Preset changes on stop, rewind, or play in GarageBand
- Keeps crashing in GarageBand (AUv3)
- Patches in standalone sound different as AUv3
- Crashes when hitting play with arpeggiator/sequencer on iPhone
- No keyboard appears in iPhone standalone mode
- Audio Unit Extension quit error on export
- Lots of crashes in standalone and hosted in AUM
- MIDI not working
- Automation still doesn’t work in Logic Pro
- Random LFO is great for recording sequences
- Preset browser closes each time a new preset is selected
- Works as AUv3 after starting in standalone mode
Requested features
20 requests- MPE popup possible on top of the auv3
- Button to hide built-in keyboard
- Buffer size option
- Additional MIDI mappings (e.g., arpeggiator toggle)
- Sustain pedal support
Show 15 moreShow fewer
- Longer LFO speed for evolving soundscapes
- Alternative skins/color themes
- Pinable preset browser
- Virtual keyboard to remain active while browser is pinned
- Make app take up whole screen (no black borders)
- Master detune
- Parameter lock
- More presets
- Fix square wave LFO to be truly square
- Fix step sequencer glide/slew for discrete steps
- Undo function in wave table editor
- Filter key follow button
- Adjust envelope curves (especially release)
- Easier way to adjust modulation matrix amount
- Phase distortion inclusion
In-app purchases
CZ App for iPad
No in-app purchases
ButterSynth
No in-app purchases









