Comparison

Kauldron Synthesizer vs Agonizer

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

Head to head
About

Kauldron Synthesizer

This app combines classic analog synth warmth with AI-powered sound design. It offers intelligent preset generation, extensive modulation options, and a powerful arpeggiator for creating rich synth textures.

Highlights
  • AI-powered preset generation (SPAWN²)
  • Analog modeling oscillators
  • Extensive modulation matrix
  • Dual XY-pads for control
  • Powerful arpeggiator
  • AUv3 plugin support
  • Over 900 presets
Read full description

Kauldron is where classic warmth meets Artificial Intelligence. One of our toniest and punchiest synths, Kauldron features a completely new analog modeling technology. The full spectrum of rich synth textures is bolstered by the groundbreaking SPAWN intelligent preset generation system that allows new patches to be created at the touch of a button. Abounding with pure hard-hitting tones, Kauldron requires little to no FX or production gimmicks to sound big. Kauldron is designed with modulation and fine dynamic control in mind. The two fully-featured LFOs and the mod envelope combine with a wide variety of MIDI learnable controls to manipulate multiple parameters. Everything is easily set up in a clearly laid out ‘mod matrix.’ The dual XY-pads can be used for controlling modulation or a wide range of synth parameters. MIDI aftertouch can be routed via the matrix for even greater control over expression and tonality. Kauldron also debuts the next generation of our Artificial Intelligence preset creation system, SPAWN². Completely reimagining the groundbreaking SPAWN algorithms in our hugely popular Magellan, the new SPAWN² gives you unprecedented control over generating presets. In the expert mode, you can accomplish anything from subtle ‘variations on a theme’ to bold new sounds. In the basic mode, where Kauldron does all the thinking, you get preset after usable preset with just a touch. This is not simple randomization: it is the power of A.I. put to benevolent use! Kauldron also includes its AUv3 plugin version so that you can seamlessly run multiple instances in your favorite DAW. Powerful arp with both live & program modes; comprehensive MIDI features with effortless MIDI learn; over 900 presets; recording, sharing, these are just some of the features brewing inside Yonac’s Kauldron. Selected specs include, SYNTH • 3 analog modeling oscillators w/ multiple waveforms & true PWM • FM via Osc 2 • Maximizer module with drift, spread & voice count for huge, stereophonic all-synth sounds • New vAnalog filter design w/ ‘dirt’ overload for even warmer, harmonically complex tones • Dedicated filter ADSR envelope • Filter tracking, contour & more • Pink/white noise generator • Osc. phase reset & sync • Retro & modern glide algorithms • Virtual VCA envelope with 2 attack types • Poly/mono operation • Legato mode for buttery smooth passages • Extensive modulation options via the ‘mod matrix’ • 2 LFOs w/ BPM sync, keytracking, trigger mode & more • Assignable mod envelope • 23 mod targets • 11 mod controllers, including aftertouch, velocity & keytracking • 2 XY-Pads for controlling mod targets or synth parameters • Arpeggiator with live & program modes, 11 algorithms, gate, swing, note value, octaving & more • Stereo mod effect with chorus & flanger modes • BPM-syncable stereo delay • Studio quality reverb w/ 7 room types, damping, time & mix • 900+ presets in a wide variety of styles & sounds SPAWN² • Automatic preset generation via artificial intelligence • Generate infinite new, usable presets at the touch of a button • Expert mode lets specify Variation & Autonomy for each major synth module • 3 unique A.I. algorithms • Auto arp programming in any listed scale PRO FEATURES • AUv3 - use as Audio Unit instrument plugin on iPad & iPhone • Fullscreen AU mode • Extensive MIDI: MIDI learn, aftertouch, MIDI CC map save/share, KB mapping, program changes & more APP • iPhone & iPad Compatibility • Powerful YPAT2 preset management system • Classic or ribbon key controller • Ribbon controller: Poly aftertouch into Kauldron • Ribbon controller: Settable musical key & scale • Classic KB: Velocity w/ sensitivity setting • Tapedeck: Record, loop & share • Metronome • Tap BPM

About

Agonizer

This app is a monophonic synthesizer focused on bass sounds, developed with a synth bass expert. It features dual wavetable oscillators, a mangle section, and built-in stereo effects. It supports MPE controllers and various audio/MIDI connectivity options for standalone or app-to-app use.

Highlights
  • Monophonic synth engine for bass
  • Dual wavetable oscillators
  • Built-in stereo effects
  • MPE controller support
  • Standalone and AUv3 operation
  • 140+ factory presets
Features
Currently charting
Read full description

Agonizer is a monophonic synthesizer designed in collaboration with YouTuber and synth bass expert Jakob Haq of haQ attaQ Overview: * Monophonic Synth Engine with focus on Bass * Built-in stereo effects * 140+ fine tuned factory presets designed by Jakob Haq * Supports ROLI Seaboard and other MPE controllers out of the box * Standalone operation with support for USB audio interfaces, wired, network & bluetooth MIDI * Audio Unit v3 Extension * Inter App Audio support * Audiobus support * Ableton Link Synth Voice: * Dual Wavetable Oscillators with 40+ Wavetables, Morphing & X-Mod * Dedicated sub osc & noise source * Mangle Section with pre-filter Drive, Bitcrush, Lift and Push controls * VA Ladder filter * Wobulator (Highly tweak-able Sequenced LFO) * LFO with Key and BPM Sync * Variable Slope AD & ADSR Envelopes * Tube based master drive Effects: * 2x stereo effect units * Vintage Chorus * Digital Delay Presets: * Factory bank including 140+ presets designed by Jakob Haq * Preset Management with Templates & Categories * Shared User Presets between Standalone and AUv3 versions * Preset Export & Import Connectivity: * Standalone * AUv3 Instrument * Inter-App Audio Instrument * Audiobus Instrument Requirements: * iOS12+ * iPad Air 2 or newer

Screenshots

Kauldron Synthesizer4 screens
Agonizer4 screens

Verdict

The call

The clearest difference is in-app purchases: Kauldron Synthesizer at none against Agonizer's 3. Agonizer's advantage is update cadence (every 5 months vs every 49 months) and chart position (#178 vs unranked). On rating, review sentiment, ratings volume and ads 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

Kauldron Synthesizer costs $9.99 and Agonizer $7.99 up front. Agonizer sells 3 one-off in-app purchases. Kauldron Synthesizer asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Agonizer holds the better App Store score, 4.8 against 4.6. Both are backed by a comparable volume of ratings — 136 and 203 respectively. Written reviews complicate that: 80% of Kauldron Synthesizer's written reviews are positive against 78% of Agonizer's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

Kauldron Synthesizer ships an update every 49 months, Agonizer every 5 months. The most recent releases landed on October 26, 2026 and October 27, 2026 respectively.

Scorecard6 real differences · 5 level
Kauldron Synthesizer versus Agonizer: the parameters behind the verdict, then further details
ParameterKauldron SynthesizerAgonizer
Price$9.99$7.99 — better
Rating4.6 (136 ratings)4.8 (203 ratings) — better
Positive reviews79.7% of reviews — better78.0% of reviews
Number of ratings136203 — better
Update frequencyEvery 49 monthsEvery 5 months — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
Best chart rank—#178 — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.611.0 — better
Further details — not scored
Size32 MB362 MB
Age rating4+4+
DeveloperYonac Inc.Kai Aras

Customer experience

Kauldron Synthesizer

All ratings136 ratings
Positive88.2%
Neutral6.6%
Negative5.1%
Written reviews74 reviews
Positive79.7%
Neutral9.5%
Negative10.8%

Agonizer

All ratings203 ratings
Positive95.6%
Neutral1.5%
Negative3.0%
Written reviews82 reviews
Positive78.0%
Neutral6.1%
Negative15.9%

User reviews

Kauldron Synthesizer

From 136 App Store ratings

What we love

  • ✨ Warm and rich sound
  • 👍 Easy to use interface
  • 💡 Great presets included
  • 🚀 Powerful sound engine
  • 🌟 High quality emulation

Room to improve

  • 🐛 Buggy AUv3 implementation
  • 🔊 Shrill noise issue
  • 🔇 No Bluetooth speaker support
  • ⚠️ Strange behavior/no reset
  • 📉 Lacks oomph/personality

Agonizer

From 203 App Store ratings

What we love

  • 🎵 Excellent sound quality and unique bass tones
  • 🎨 Intuitive and well-designed user interface
  • ⚙️ Powerful modulation and sound design capabilities
  • 🎛️ Wobulator feature for creative bass manipulation
  • 📦 Great presets included with the app

Room to improve

  • 🐛 Keyboard legato/mono-synth behavior inconsistent
  • 🐛 Frequent crashes in host applications (AUM, Cubasis, Audiobus)
  • 🐛 No sound output in GarageBand and some AU hosts
  • 🐛 App freezes on splash screen with iOS 18.3
  • 🐛 UI responsiveness issues and knob lag

Bugs and requests

Kauldron Synthesizer

Reported bugs

15 issues
  • Oscillators cannot be set to -1 octave
  • Shrill noise
  • No Bluetooth speaker output
  • Fails to reload with Logic projects
  • Cannot load into Logic Pro
Show 10 more
  • Starts and quits on latest iOS
  • AUv3 bug: receives notes regardless of track selection
  • AUv3 implementation flaky, random crashes
  • AUv3: plays all instances simultaneously
  • Bug with Garageband: duplicates patterns
  • MIDI learn functions not saved
  • Sometimes glitchy
  • XY pad movements not recorded as automation
  • CPU killer on iPad 4
  • No function to share sounds

Requested features

11 requests
  • Bring synths/effects to macOS
  • Mac App version
  • More comprehensive FX section (distortion/saturation)
  • MIDI-out for arpeggiator
  • Drum machine, PAD launcher, DAW
Show 6 more
  • Browser download feature
  • Sequencer in Kauldron
  • Effects tool
  • Version history
  • More developer responses/support
  • Dark mode option

Agonizer

Reported bugs

16 issues
  • Keyboard does not properly handle legato/mono-synth note priority
  • Crashes in Audiobus, AUM, and Cubasis host applications
  • No sound output when used as AUv3 plugin in hosts
  • No sound in GarageBand integration
  • App freezes on splash screen with iOS 18.3
Show 11 more
  • Stuck notes and failed note triggering
  • Scream button malfunction when switching presets
  • Cutoff knob lag in AUv3 scenarios
  • UI jitter and text cutoff on iPhone
  • Favorite preset feature not working on iPhone
  • Program change not working properly in hosts
  • Always opens with init preset in host applications
  • Modulation matrix sensitivity too high (2% movement = large range)
  • Audio output peaks in red with no sound
  • Permanent clipping/damaged audio output
  • Misleading IAP pricing display (showing 'FREE' for paid content)

Requested features

10 requests
  • Polyphony mode or toggle between mono and poly
  • Envelope drawing capability instead of preset selection
  • Menu-based waveform selection instead of cycling
  • Arpeggiator function
  • Preset browser search and favorites filter
Show 5 more
  • Extended automation control for all knobs
  • Keytracking for filter
  • Reverb effect
  • Accelerometer/gyroscopic velocity sensitivity
  • Customizable number of keyboard keys

In-app purchases

None

Kauldron Synthesizer

No in-app purchases

3 purchases

Agonizer

One-time3
  • Neon Nightmare Pack$1.99
  • Chrome Oasis Pack$1.99
  • Circuit Bender Pack$1.99

Questions

Is Kauldron Synthesizer free?
Kauldron Synthesizer costs $9.99, with no in-app purchases.
Is Agonizer free?
Agonizer costs $7.99, and also offers in-app purchases.
Which has better reviews, Kauldron Synthesizer or Agonizer?
Agonizer is rated higher. Kauldron Synthesizer averages 4.6 out of 5 from 136 ratings, while Agonizer averages 4.8 from 203 ratings.
Do Kauldron Synthesizer or Agonizer have ads?
Neither Kauldron Synthesizer nor Agonizer shows ads.
Which is updated more often, Kauldron Synthesizer or Agonizer?
Kauldron Synthesizer ships an update every 49 months, and Agonizer every 5 months. Most recently, Kauldron Synthesizer was updated on October 26, 2026 and Agonizer on October 27, 2026.

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