Comparison

SWAM Viola vs ButterSynth

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

SWAM Viola

This virtual instrument uses physical modeling to generate realistic string performances in real-time, responding dynamically to your playing style. It offers advanced spatial control with a built-in room simulator and can be used standalone or as an AUv3 plugin. Designed for expressive control, it's suitable for various musical styles and accessible to visually impaired users.

Highlights
  • Physical modeling sound generation
  • Real-time dynamic response
  • Built-in Room Simulator (Ambiente)
  • Standalone and AUv3 plugin support
  • Intuitive interface for all users
  • MPE and MIDI controller support
  • Customizable timbre, vibrato, and dynamics
Read full description

SWAM Viola for iOS: Unmatched Realism and Expressive Power in Your Hands Experience the cutting-edge Physical Modeling technology of SWAM Viola for iOS, now featuring the revolutionary Room Simulator "Ambiente"! Unlike sampled libraries, this virtual instrument doesn’t play pre-recorded sounds but generates authentic string performances in real-time, responding dynamically to your every nuance, just like a real violist. These instruments are NOT sample libraries. Unlike sampling, which uses recordings to replicate the sound of an instrument, physical modeling doesn’t generate a sound as such but creates the conditions for the system to create it according to an external input (like someone playing on a keyboard). This means every note is unique, and the instrument responds dynamically to your playing style. With SWAM Viola, you can unleash your creativity across any musical style—from classical to modern, film scoring to microtonal music. Whether you're performing live or producing music on the go, SWAM Viola is your ultimate companion. New Features and Key Benefits: Room Simulator "Ambiente": Take advantage of advanced spatial control with the built-in Room Simulator "Ambiente," which allows you to position the instrument in a realistic acoustic space, interact dynamically with other SWAM instruments in the same virtual room, and create truly immersive performances. Additionally, the legacy Reverb, EQ, and Compressor effects are available for fine-tuning your sound. Standalone and AUv3 Plugin: Perform in real time or integrate SWAM Viola seamlessly into your mobile production workflow. Intuitive, Inclusive Interface: Designed for everyone, including blind and visually impaired users. Expressive Control: Play with unmatched expressivity using the exclusive virtual bowing surface, MPE controllers, keyboards, breath controllers, or other MIDI devices. Top Features at a Glance: Access a library of presets, create your own, or import presets from the desktop version. Customize every detail of your sound, including timbre, vibrato, and dynamics. Micro-tune the instrument with the Pitch Manager, supporting devices like MAQAM for advanced tuning systems. Add built-in effects like EQ, and Compressor. Play with different viola bodies to explore unique tonal variations. Use AUv3 to integrate with your mobile DAW (Logic, Cubasis, AUM) or apps like Camelot PRO for live performances. Who is SWAM Viola for iOS Designed For? Wind Controller Players: Looking for a mobile setup to perform live without needing a computer while still achieving an incredible sound. Keyboard Players: Frustrated by the limited expressive capabilities of normal sample-based plugins? SWAM Viola unlocks the full range of expression. Music Producers: Need a mobile setup to produce music from anywhere without carrying around expensive gear? SWAM Viola is the solution. Musicians Seeking Expressivity: Looking for a virtual instrument that allows you to express the full range of your musicality easily on your iPhone or iPad. IMPORTANT: To fully harness the expressive power of SWAM Viola, a controller capable of continuous expression (such as a breath controller, expression pedal, MPE device, or wind controller) is required. Just like a bow is essential for a real violist, SWAM Viola needs expressive input for maximum realism. With SWAM Viola for iOS, you have the freedom to create lifelike string performances on your iPhone or iPad. Redefine your music with unparalleled realism and expressive depth—anytime, anywhere.

About

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.

Highlights
  • 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
Features
Read 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

SWAM Viola4 screens
ButterSynth4 screens

Verdict

The call

The clearest difference is price: ButterSynth at $19.99 against SWAM Viola's $29.99. ButterSynth also leads on ratings volume (63 vs 6). SWAM Viola's advantage is review sentiment (100% vs 59%) and rating (4.3 vs 4.0). 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

CostPrice · In-app purchases · Ads · Monetization

SWAM Viola costs $29.99 and ButterSynth $19.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

SWAM Viola holds the better App Store score, 4.3 against 4.0. That said, the two scores are not equally well evidenced: ButterSynth has 63 ratings behind it against 6, so its average is the more settled of the two. Written reviews point the same way: 100% of SWAM Viola's written reviews are positive against 59% of ButterSynth's.

UpkeepUpdate frequency

SWAM Viola ships an update every 5 weeks, ButterSynth every 2 months. The most recent releases landed on October 25, 2026 and October 27, 2026 respectively.

Scorecard4 real differences · 6 level
SWAM Viola versus ButterSynth: the parameters behind the verdict, then further details
ParameterSWAM ViolaButterSynth
Price$29.99$19.99 — better
Rating4.3 (6 ratings) — better4.0 (63 ratings)
Positive reviews100.0% of reviews — better59.2% of reviews
Number of ratings663 — better
Update frequencyEvery 5 weeks — betterEvery 2 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.014.0 — better
Further details — not scored
Size103 MB468 MB
Age rating4+4+
DeveloperAudio ModelingArto Vaarala

Customer experience

SWAM Viola

All ratings6 ratings
Positive83.3%
Neutral0.0%
Negative16.7%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

ButterSynth

All ratings63 ratings
Positive73.0%
Neutral7.9%
Negative19.0%
Written reviews71 reviews
Positive59.2%
Neutral11.3%
Negative29.6%

Bugs and requests

SWAM Viola

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 more
  • 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 more
  • 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

None

SWAM Viola

No in-app purchases

None

ButterSynth

No in-app purchases

Questions

Is SWAM Viola free?
SWAM Viola costs $29.99, with no in-app purchases.
Is ButterSynth free?
ButterSynth costs $19.99, with no in-app purchases.
Which has better reviews, SWAM Viola or ButterSynth?
SWAM Viola is rated higher. SWAM Viola averages 4.3 out of 5 from 6 ratings, while ButterSynth averages 4.0 from 63 ratings.
Do SWAM Viola or ButterSynth have ads?
Neither SWAM Viola nor ButterSynth shows ads.
Which is updated more often, SWAM Viola or ButterSynth?
SWAM Viola ships an update every 5 weeks, and ButterSynth every 2 months. Most recently, SWAM Viola was updated on October 25, 2026 and ButterSynth on October 27, 2026.

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