Comparison

Caustic vs AudioKit Digital D1 Synth

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

Head to head
About

Caustic

Create music with a virtual synthesizer and sampler rig. Build your sound by adding up to 14 machines, including synths and drum machines. Features a mixer, effects, and a song sequencer for real-time audio production.

Highlights
  • Virtual analog subtractive synthesizer
  • Multi-sample wave synthesizer
  • Sampling drum machine
  • Effects rack with 20 effect types
  • Mixer desk with EQ and effects
  • Song sequencer
  • AudioBus and AudioCopy/Paste support
Features
Read full description

Caustic 3 is a music creation tool inspired by rack-mount synthesizer/sampler rigs. Everything is real-time and optimized for mobile devices. Create your rack by adding up to 14 machines from a choice of: * Subsynth - Virtual analog subtractive synthesizer * PCMSynth - Multi-sample wave synthesizer * BassLine - 303-like monosynth * BeatBox - 8-channel sampling drum machine * PadSynth - Harmonic table pad synthesizer * 8BitSynth - 8bit equation solver synthesizer * Modular - Fully configurable and routable synthesizer * Organ - Tonewheel organ with rotary speaker * Vocoder - 8-band harmonic vocoder * FMSynth - DX-style 3-operator fm synthesizer * KSSynth - Karplus-Strong string modeling synthesizer * SawSynth - Supersaw-type synthesizer The app also includes: * Effects rack supporting 2 effects per machine (20 effect types). * Mixer desk with EQ, panning and global Delay/Reverb effects. * Master section with effect slots, parametric EQ and limiter. * Song sequencer AudioBus support for Input and Output slots. AudioCopy Paste + AudioShare support for import and export. Supports automation recording on most controls and includes powerful editors for modifying automation curves. Users can record their own WAV files for use in the PCMSynth, BeatBox, and Vocoder or import files through iTunes file sharing, ACP, AudioShare, or the built-in FTP server. Supports all uncompressed WAV files (8-16-24-32bit, any sampling rate). The PCMSynth can also load SoundFont files (.sf2), SFZ and FL/Xewton instruments (.instr, .ZIP) "Open In.." import support for all preset types, .WAV, .SF2 and .MID. (MIDI (.mid) files can be imported as raw sequencer note data.) Supports CoreMIDI and virtual MIDI for note, velocity and CC data. (be sure to set "Enable background audio" in advanced options to use virtual MIDI) See the in-app help section for dozens of informative tutorial videos and full online manual. There is also a FREE (full version) PC/Mac version available for download on the product website. Come visit www.singlecellsoftware.com to download more presets, request features, share your tracks and hear what others are creating with Caustic 3. Works on iPhone/iPod but iPad is recommended.

About

AudioKit Digital D1 Synth

This app is a virtual analog and PCM synthesizer for iPad, inspired by the digital synthesizers of the 80s and 90s. It offers a vast library of presets, advanced synthesis features, and built-in effects for creating rich, retro-inspired sounds.

Highlights
  • 64-voice hybrid digital poly synthesis
  • 1GB+ of original samples
  • Stand-alone, IAA, and AUv3 support
  • Vintage-style arp/step sequencer
  • 3 LFOs with fun routings
  • Dual independent per-layer filters
  • Built-in FX suite
Read full description

Epic 64-voice Virtual Analog / PCM iPad Synth Inspired by the Digital Synths of the 80s and 90s - ** TOP 3 iOS MUSIC APPS OF 2018 *** - Music Radar Awards (Computer Music & Future Music Magazine) - * Featured By Apple in "New Apps We Love!" ** "Fans of the D-50, JD-990, 01/W, Wavestation... Rejoice!" - Music Radar FULLY LOADED w/ 500+ presets by Brice Beasley, Matthew Fecher, Red Sky Lullaby, Jakob Haq, Dean Daughters (Electronisounds), Sound of Izrael, Brian Funk, and more DIGITAL D1 is AWESOME: - 64-voice Hybrid Digital Poly Synthesis. - Full 1+ Gigabyte of original samples recorded from analog & fm synths over 30+ years old - Stand-alone iPad Synth, plus IAA & Audiobus - Basic AUv3 Plugin support. Works best with AUM. We're working on upgrading Audio Unit support. - Space-saving Compression - The whole app is under 200mb! - Dual layers per voice. Keyboard splits. Velocity Scaling. - Vintage-style Arp/Step Sequencer that can be routed to specific layers. - 3 LFOs. Fun Routings. LFOs can modify other LFOs. - Dual Independent per-Layer filters - Plus, per-voice Harmonic key-tracked Envelope filters. "Digital D1 Sounds and plays AMAZING!" - The Sound Test Room "Rad retro synth sounds" - Cult of Mac, App of the Week "AudioKit Digital D1 is a beautiful Synthesizer app that recreates the spirit of legendary synths" - Synth Anatomy ADDITIONAL FEATURES: - FX: Glorious Reverb, Phaser, Digital Delay, Distortion, Flanger, Chorus, Crush, and more. - Perfect with a MIDI Keyboard - Ableton Link - All kinds of awesome stuff - The Sound. Oh, the sound. You won't believe it. "Digital D1 synth is pure ‘80s and ‘90s digital lushness" - Computer Music/Music Radar "Beautiful. Lush. Modern and Amazing… An Instant Classic." REQUIREMENTS: Requires newer iPads for best performance. May be slow on iPad 4. IAA is being deprecated by Apple in iOS 13. We're moving to AUv3 as well. Please replace IAA with AUv3 in your projects. GarageBand Audio Unit (AUv3): You can run one instance of D1 as an AUv3 in GarageBand. With a host like AUM, you can run 3 or more instances at once. TROUBLESHOOTING: For iPad 4 - Open the "Settings" button (to the upper left above the keyboard). Turn the buffer to 512 or above. And turn the "CPU Efficient" toggle to on. If still having trouble, try closing other music apps and/or rebooting your iPad. Thanks! - * NOMINATED: Best iOS Music Apps of 2018 ** by Computer Music & Future Music magazine. Subscribe to access to premium app features; subscription details are the following: - Length: weekly or yearly - Free trial: only on selected subscriptions - Your payment will be charged to your iTunes Account as soon as you confirm your purchase - You can manage your subscriptions and turn off auto-renewal from your Account Settings after the purchase - Your subscription will renew automatically, unless you turn off auto-renew at least 24 hours before the end of the current period - The cost of renewal will be charged to your account in the 24 hours prior to the end of the current period - When canceling a subscription, your subscription will stay active until the end of the period. Auto-renewal will be disabled, but the current subscription will not be refunded - Any unused portion of a free trial period, if offered, will be forfeited when purchasing a subscription Terms & Conditions: [https://magic-cake-e95.notion.site/AudioKit-Digital-D1-Synth-Terms-Conditions-14dcf6557a0880beb991f20561329664?pvs=4](https://www.notion.so/AudioKit-Digital-D1-Synth-Terms-Conditions-14dcf6557a0880beb991f20561329664?pvs=21) Privacy Policy: [https://magic-cake-e95.notion.site/AudioKit-Digital-D1-Synth-Privacy-Policy-14dcf6557a088042b2beee2382f5d62f?pvs=4](https://www.notion.so/AudioKit-Digital-D1-Synth-Privacy-Policy-14dcf6557a088042b2beee2382f5d62f?pvs=21) - * NOTE: This app has no official affiliation with AudioKit Pro, LLC. It was built using the free AudioKit source code.

Screenshots

Caustic4 screens

Verdict

The call

The clearest difference is price: AudioKit Digital D1 Synth at Free against Caustic's $9.99. AudioKit Digital D1 Synth also leads on rating (4.8 vs 3.5) and update cadence (every 3 weeks vs every 4 months). Caustic's advantage is in-app purchases (none vs 6) and ads (none vs shown).

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

AudioKit Digital D1 Synth is free to download; Caustic costs $9.99 up front. AudioKit Digital D1 Synth sells 6 in-app purchases, starting at $4.99 per 7 days. Caustic asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

AudioKit Digital D1 Synth holds the better App Store score, 4.8 against 3.5. That said, the two scores are not equally well evidenced: AudioKit Digital D1 Synth has 2K ratings behind it against 176, so its average is the more settled of the two. Written reviews point the same way: 58% of Caustic's written reviews are positive against 76% of AudioKit Digital D1 Synth's.

UpkeepUpdate frequency

Caustic ships an update every 4 months, AudioKit Digital D1 Synth every 3 weeks. The most recent releases landed on October 16, 2026 and October 13, 2026 respectively.

Scorecard10 real differences · 0 level
Caustic versus AudioKit Digital D1 Synth: the parameters behind the verdict, then further details
ParameterCausticAudioKit Digital D1 Synth
Price$9.99Free — better
Rating3.5 (176 ratings)4.8 (2K ratings) — better
Positive reviews57.8% of reviews76.1% of reviews — better
Number of ratings1762K — better
Update frequencyEvery 4 monthsEvery 3 weeks — better
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationPaid — betterSubscription
DevicesiPhone, iPad, iPod — betteriPad
Requires iOS7.0 — better13.0
Further details — not scored
Size52 MB636 MB
Age rating4+4+
DeveloperRejean PoirierAudiobus Pty Ltd

Customer experience

Caustic

All ratings176 ratings
Positive60.2%
Neutral8.5%
Negative31.3%
Written reviews218 reviews
Positive57.8%
Neutral7.8%
Negative34.4%

AudioKit Digital D1 Synth

All ratings2,007 ratings
Positive95.4%
Neutral1.7%
Negative2.9%
Written reviews243 reviews
Positive76.1%
Neutral7.4%
Negative16.5%

User reviews

Caustic

From 176 App Store ratings

What we love

  • 🚀 Powerful and feature-rich
  • 👍 Intuitive workflow
  • 🎨 Excellent sound quality
  • 💸 Great value for money

Room to improve

  • 🐛 Compatibility issues with newer iOS versions
  • 🔇 No Bluetooth audio support
  • 📁 Difficulty accessing/exporting files
  • 🔧 Needs more updates and bug fixes

AudioKit Digital D1 Synth

From 2K App Store ratings

What we love

  • 🎨 Excellent sound quality
  • 🎹 Versatile and inspiring presets
  • 👍 Intuitive and user-friendly interface
  • 💰 Great value for the price
  • 🔥 Cutting-edge digital synthesis

Room to improve

  • 🐛 Occasional crashes and stability issues
  • 🔋 High battery consumption
  • 🔒 Lack of Audio Unit (AUv3) support
  • 🤔 Some presets not easily usable
  • 🕰️ Slow loading times in certain DAWs

Bugs and requests

Caustic

Reported bugs

3 issues
  • Crashes and freezes on newer iPhones
  • Interface scaling problems on larger screens
  • Unresponsive controls in certain scenarios

Requested features

4 requests
  • Bluetooth audio support
  • Improved file management and export options
  • More synth/instrument options
  • Expanded effects and mixing capabilities

AudioKit Digital D1 Synth

Reported bugs

4 issues
  • Presets not loading correctly
  • MIDI note dropouts and latency
  • Crashes when used with certain DAWs
  • Compatibility issues with newer iOS versions

Requested features

5 requests
  • Add Audio Unit (AUv3) support
  • Improve MIDI integration and responsiveness
  • Implement a built-in recording/sampling feature
  • Expand preset library with more genres and styles
  • Add more sound design controls and modulation options

In-app purchases

None

Caustic

No in-app purchases

6 purchases

AudioKit Digital D1 Synth

Subscriptions4
  • Weekly premium$4.997 Days
  • Weekly premium7 Days trial$4.997 Days
  • Yearly premium7 Days trial$9.991 Year
Show 1 more
  • Yearly premium$9.991 Year
One-time2
  • D1 PCM Expansion-01Free
  • Platinum Expansion PCM EXP-01Free

Questions

Is Caustic free?
Caustic costs $9.99, with no in-app purchases.
Is AudioKit Digital D1 Synth free?
AudioKit Digital D1 Synth is free to download, with in-app purchases available.
Which has better reviews, Caustic or AudioKit Digital D1 Synth?
AudioKit Digital D1 Synth is rated higher. Caustic averages 3.5 out of 5 from 176 ratings, while AudioKit Digital D1 Synth averages 4.8 from 2K ratings.
Do Caustic or AudioKit Digital D1 Synth have ads?
AudioKit Digital D1 Synth shows ads; Caustic does not.
Which is updated more often, Caustic or AudioKit Digital D1 Synth?
Caustic ships an update every 4 months, and AudioKit Digital D1 Synth every 3 weeks. Most recently, Caustic was updated on October 16, 2026 and AudioKit Digital D1 Synth on October 13, 2026.

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