Comparison

Pure Acid vs ButterSynth

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

Head to head
About

Pure Acid

This app is a high-quality bassline synthesizer and drum machine inspired by classic 80s hardware. It offers a retro analog sound with modern features for fast and fun music creation. Explore various genres with factory presets and create unique rhythms and basslines.

Highlights
  • AUv3, Ableton Link, AudioBus, IAA support
  • Classic bassline waveforms (Saw, Pulse)
  • Distortion and filter LFO effects
  • 32-step sequencer with pattern editing
  • 16 independent drum parts with customizable sounds
  • Realtime master effects with XY-pad
Currently charting
Read full description

Pure Acid is a top quality bassline synthesizer and drum machine in one app! Inspired by classic hardware bassline synthesizers and rhythm machines, which changed musical world back in 80's, like the legendary TB-303 synthesizer, TR-808 / 707 / 909 rhythm boxes and their numerous replicas, Pure Acid is designed to bring back the feeling of retro analog gear in every detail in terms of sound, as well as to provide new functions previously unavailable in the original devices to make your music creation workflow fast and fun! A large number of factory preset patterns will immerse you into an exciting world of Acid House, Techno, Hardcore and Big Beat music genres, which will inspire you to create your own basslines and rhythms for your compositions! You can use Pure Acid app as a ready-to-go realtime musical instrument (groove box) in your jam sessions together with Ableton Link to synchronize it with the rest of your music gear. Its bassline editing system and randomization options will be handy to create unique groovy basslines easily. Realtime master effects with XY-pad controls can add expression to your live performance. You can also use Pure Acid with AudioBus, AUM or other IAA-supporting apps to create complex and interesting sound setups. Features: • supports AUv3, Ableton Link, AudioBus, Inter-App Audio, Core Midi, Virtual Midi In/Out, Bluetooth Midi • AudioBus state saving support • 64-bit sound engine • Midi Learn • Export to midi file • includes Multiple Output AUv3 plugin with 6 audio output busses Bassline Section: • 2 classic bassline waveforms: Saw and Pulse • classic knobs: Tune, Cutoff, Resonance, Env Mod, Decay and Accent • Distortion effect with amount, HPF and Boost knobs • filter LFO with rate and depth knobs Sequencer Section: • up to 12 bassline patterns can be stored in one preset • up to 32 steps per each bassline pattern • patterns can be chained together to create more complex patterns • pattern Tempo and Swing parameters • Gate parameter, which allows you to adjust bass note lengths • Pattern Editor allows you to copy, transpose patterns, shift notes left/right, insert or delete a note, variate (randomize all note properties expect pitch), shuffle (randomize notes order only), reverse and compose patterns using Bassline Composer function • onscreen keyboard allows you to enter bassline notes in a comfortable way. You can also record basslines in realtime. Drums Section: • 16 independent drum parts • 35 different classic drum sounds with ability to tune your own drum kit • each drum part sound has its own parameters: Tune, Decay, Attack/Snap/Color, FX A send, FX B send, Boost, Pan, Level • up to 12 drum patterns and 4 drum fill patterns per preset • 16 steps per each drum pattern, with ability to add 16 "backbeat" steps between main steps (32 steps per drum pattern in total) • patterns can be chained together to create more complex patterns • Swing and Flam features • Total Accent part with adjustable total accent value can give you ability to "highlight" specific steps in your drum pattern • new: step conditions for drum steps Mixer Section: • 2 mixer channels: Bassline and Drums • Drive effect for each channel • 2 send effect pedals: FX A and FX B • 14 send effect types • send effect can be routed to either master output, MFX or another send effect (FX A -> FX B), which allows to chain several effects one after another • MFX pedal with 22 effect types to choose from • FX A and FX B send amount knobs for each mixer channel • XY-pad on each effect pedal to control their parameters • Master Limiter effect to prevent sound clipping and more: • Unlimited number of user presets • 84 factory presets • Audio export to wav file (16, 24 or 32 bit) • Preset / Bank Share function • Selectable UI color schemes with ability to adjust colors manually • Can work either as a standalone app, or as AUv3 audio unit plugin • Designed for both iPad and iPhone

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
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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

Pure Acid4 screens
ButterSynth4 screens

Verdict

The call

The clearest difference is price: Pure Acid at $7.99 against ButterSynth's $19.99. Pure Acid also leads on rating (4.9 vs 4.0) and review sentiment (94% vs 59%). ButterSynth's advantage is in-app purchases (none vs 2). On ratings volume, ads, 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

CostPrice · In-app purchases · Ads · Monetization

Pure Acid costs $7.99 and ButterSynth $19.99 up front. Pure Acid sells 2 one-off in-app purchases. ButterSynth asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Pure Acid holds the better App Store score, 4.9 against 4.0. Both are backed by a comparable volume of ratings — 169 and 63 respectively. Written reviews point the same way: 94% of Pure Acid's written reviews are positive against 59% of ButterSynth's.

UpkeepUpdate frequency

Pure Acid ships an update every 3 weeks, ButterSynth every 2 months. Both last shipped on October 29, 2026.

Scorecard7 real differences · 4 level
Pure Acid versus ButterSynth: the parameters behind the verdict, then further details
ParameterPure AcidButterSynth
Price$7.99 — better$19.99
Rating4.9 (169 ratings) — better4.0 (63 ratings)
Positive reviews94.1% of reviews — better59.2% of reviews
Number of ratings169 — better63
Update frequencyEvery 3 weeks — betterEvery 2 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
Best chart rank#114 — better—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS13.0 — better14.0
Further details — not scored
Size44 MB468 MB
Age rating4+4+
DeveloperDmitrij PavlovArto Vaarala

Customer experience

Pure Acid

All ratings167 ratings
Positive97.0%
Neutral1.8%
Negative1.2%
Written reviews152 reviews
Positive94.1%
Neutral2.6%
Negative3.3%

ButterSynth

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

User reviews

Pure Acid

From 169 App Store ratings

What we love

  • 🚀 Powerful and feature-rich
  • 👍 Intuitive and easy to use
  • 🎶 Excellent sound quality
  • 🎛️ Great sequencing and programming capabilities
  • 🔌 Seamless integration with other apps and hardware

Room to improve

  • 🐛 Occasional audio cutoff or sync issues
  • 🔍 Lack of detailed documentation or tutorials
  • 🔀 Limitations in pattern length and drum sequencing

ButterSynth

From 63 App Store ratings

What we love

  • ✨ Deep sound design capabilities
  • 🎛️ Versatile modulation matrix
  • 🔊 Great sound quality
  • 💡 Innovative wavetable generator
  • 🌟 Serum-like experience

Room to improve

  • 📱 Fiddly on small screens
  • 🐛 Crashes frequently
  • 🐛 Disappears in Cubasis
  • 🐛 Spikes CPU usage
  • 🐛 Crashes on patch change

Bugs and requests

Pure Acid

Reported bugs

2 issues
  • GUI scaling issues on smaller devices
  • Crashes or freezes on certain devices

Requested features

4 requests
  • Ability to import MIDI files
  • Standalone drum machine mode
  • Expanded drum sample library
  • Knob/parameter automation recording

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

2 purchases

Pure Acid

One-time2
  • Ukrainian style color scheme$4.99
  • Ukrainian style app icon$4.99
None

ButterSynth

No in-app purchases

Questions

Is Pure Acid free?
Pure Acid costs $7.99, and also offers in-app purchases.
Is ButterSynth free?
ButterSynth costs $19.99, with no in-app purchases.
Which has better reviews, Pure Acid or ButterSynth?
Pure Acid is rated higher. Pure Acid averages 4.9 out of 5 from 169 ratings, while ButterSynth averages 4.0 from 63 ratings.
Do Pure Acid or ButterSynth have ads?
Neither Pure Acid nor ButterSynth shows ads.
Which is updated more often, Pure Acid or ButterSynth?
Pure Acid ships an update every 3 weeks, and ButterSynth every 2 months. Most recently, Pure Acid was updated on October 29, 2026 and ButterSynth on October 29, 2026.

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