Comparison

KeyStage vs NuRack Auv3 FX Processor

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

Head to head
About

KeyStage

This app acts as a master controller, AUv3 host, and audio mixer for keyboard players. It allows simultaneous control of multiple hardware and software instruments via MIDI, with advanced mapping, scripting, and audio mixing capabilities.

Highlights
  • Connect multiple MIDI controllers to instruments
  • Load AUv3 instruments, effects, and MIDI processors
  • Create complex keyboard splits and layers
  • Advanced MIDI mapping and scripting
  • Audio mixer with volume and pan control
  • Play and automate audio files
  • View PDF and JPG files
Read full description

TRY THE FREE LITE VERSION: https://apps.apple.com/us/app/keystage-lite/id1437899019 KeyStage is a master controller, AUv3 host, and audio mixer app designed mainly for keyboard players. With KeyStage, you can simultaneously control any number of hardware and software instruments using any number of MIDI controllers in an organized way. Each project consists of sections (which corresponds to sections of a song). In each section you can change sounds and sound parameters of connected instruments, create complex splits and layers of your keyboard(s), change the functionalities of sliders/knobs/pedals of your MIDI controllers by creating advanced MIDI mappings, write your own scripts, view PDF and JPG files (e.g. sheet music) and lyrics, and much more. LIST OF FEATURES • Connect any number of MIDI controller to any number of MIDI instruments by creating tracks. • Load AUv3 instruments, effects, and MIDI Processors. • Assign any region of your keyboard(s) to any connected instrument. • Change velocity curve and velocity limits, and create velocity splits and layers. • Transpose notes and restrict notes to any key using pitch shifter. • Create mixer units to combine audio signals, turning KeyStage into an audio mixer. • With the player units, you can play wav, mp3, and m4a files, add marker points, automate actions (like play, stop, move to a marker etc.) using custom translators, or trigger certain events (like changing sections) when the player reaches a certain marker. • Input units allows you to use the microphone input, or the hardware inputs of a connected audio interface. • The Main Mixer view allows you to control volume levels and pans of all tracks, connect effect units, and connect units to mixer units. • Create instrument presets to easily change sounds of instruments by choosing patch names from patch lists. • KeyStage can also import Cubase Patch Scripts to automatically create instrument presets for your MIDI instruments. • KeyStage automatically detects new MIDI connections and recommends matching instrument presets from a database. • Simulate auto-sustain on any connected instrument. • KeyStage has a multi-track recorder, which lets you record any number of tracks simultaneously. • Change or filter any MIDI signal using custom translators. Use “Relative Control” switch to smoothly change the parameters of your instruments without any jumps. • Use XY control unit to send control change and pitch bend messages to any connected MIDI instrument. • Create setlists, quick access all the songs in a setlist from a setlist bar, move to previous/next songs from live console or using external MIDI. • Create virtual MIDI inputs/outputs for KeyStage. • Use virtual MIDI piano controller to play connected instruments. • View PDF and JPG files. Link any page or region of any file to any section. • Backup and restore your songs and global properties to Dropbox. • Map special actions (like changing octaves, switching sections, changing pages of a PDF file) to notes and controllers using custom translators. • You can write your own scripts in custom translators, which opens up endless possibilities. • Use MPE routing to control any MIDI instrument using MPE controllers like Seaboard. Use custom translators to change the functionalities of each MPE dimension. • KeyStage supports smooth transitions between sections. Pressed notes will continue to sound when you switch sections. You can access demo videos and video tutorials on my Youtube channel.

About

NuRack Auv3 FX Processor

Design custom audio and MIDI effects racks with over 80 building blocks. Route audio in series or parallel and create unique interfaces for your sound processing needs.

Highlights
  • Design custom effects racks
  • Over 80 audio and MIDI building blocks
  • Full routing control (series/parallel)
  • Customizable interface builder
  • Seamless effect switching
  • 3 independent audio racks mode
  • Extensive automation options
Currently charting
Read full description

NuRack is an AUv3 based multi-channel audio and MIDI effects processor with a difference, it actually allows you to design your own custom effects using the 80+ building blocks provided. You have full control over routing which allows you to create complex audio paths in series or parallel. You can choose whether to use the stock interface or create your own custom interface using the built in Interface Builder which allows you to concentrate your audio components into a single customized effect. NuRack can run in one of two modes. The first providing 3 customizable effects racks which can be switched (manually or via MIDI), providing seemless switching (i.e. delay trails linger whilst another set of effects are faded in). The second mode allows you to route audio through 3 independent audio racks. A generaous number of over 80 audio and midi building blocks are provided covering 12 different categories of effects. Here are just some of those included in NuRack: Modulation Effects: Chorus, Flanger, Phaser, Tremolo, Vocal Doubler, TalkBox, UniVibe, Leslie & Vocoder. Time Based Effects: Stereo Delay, Tape Delay, Reverb and Reverse Delay. Spectral Effects: Parametric EQ, Graphic EQ, PitchShift, Auto-Pan, Bit-Crusher, Tube Overdrive, Distortion, Harmony, Harmonic Exciter and SlowMo. Dynamic Effects: VelocityControl, Compressor, Multi-Band Compressor, Noise Gate, Gate, and Limiter. Filter Effects: MultiFilter, LP/HP Filter, Frequency Splitter, MultiBand Splitter, Classic Filters, Formant Filter, Ring Modulation and Shelf Filter. MIDI Effects: MIDI Harmony, MIDI Velocity, MIDI Randomizer, MIDI Monitor, MIDI Mixer, MIDI Pads, MIDI Control, Strummer, MIDI Recorder, MIDI Modulation, MIDI Remap, CC Monitor, CC Generator, PitchBend, MIDI Time Clock, and ChordToMidi. Generator Modules: Noise, Audio Clip Launcher, SoundFont Player, Virtual Flute, Virtual Clarinet, Virtual Brass, FM Organ, FM Rhodes and Analog Sawtooth Synth. Automation: TouchPad, AutoMate, Pattern Automation, and Visual LFO. You also provide the ability to split and combine audio signal using splitters and mixer modules as well as a number of visual elements such as VU Meters, LED Meters, Scopes, Graphs etc. Some effects such as phaser and flanger are usually controlled by an LFO, but this can be detached and automated remotely. There are a number of modules that allow auomation based on direct touch (X/Y Pads), Visual LFO, Pattern Automation, MIDI input (CC data), or peak/rms level detection. These automation modules can remotely control knobs and sliders throughout your rack. Simply create a new rack and start adding modules to it. These modules are generally wired up automatically but these connections can be manually routed. Once you have your sound as you wish you can use it 'as is', or switch to Interface Builder mode where you can combine all your modules into a single interface. Elements can be dragged, dropped, resized and coloured as required. Add your own labels, image logos and custom backgrounds before saving your custom component. Use the X/Y Pad to control your modulation effects by detaching their LFO's. Use MIDI CC data to automate knobs. Use the velocity of an incoming signal to control the cutoff/resonance of a filter (wah) or volume level of a gain control (swell), as NuRack expands, so do the possibilities. Features: ○ Over 80 categorised modules. ○ 3 Input / Output busses supported. ○ Audio & MIDI effect. ○ Lots of audio & MIDI automation options. ○ Seemless transition between racks. ○ Manual audio path routing. ○ Open in presentation mode (auto hides controls). ○ Interface Builder to customize your rack. ○ AUv3 plugin runs in MIDI and none MIDI mode. ○ Add your own Text/Heading and Image/Logos and backgrounds to your design. ○ Compatibility options for DAW's not supporting multi-channels. ○ Dark/Light Modes Checkout the YouTube channel 'Paul the MusicMan' for demos and tutorials of NuRack.

Screenshots

NuRack Auv3 FX Processor4 screens

Verdict

The call

The clearest difference is price: NuRack Auv3 FX Processor at $7.99 against KeyStage's $29.99. NuRack Auv3 FX Processor also leads on in-app purchases (none vs 7) and update cadence (every 3 weeks vs every 3 months). 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

KeyStage costs $29.99 and NuRack Auv3 FX Processor $7.99 up front. KeyStage sells 7 one-off in-app purchases. NuRack Auv3 FX Processor asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 4.7 for KeyStage against 4.7 for NuRack Auv3 FX Processor. Both are backed by a comparable volume of ratings — 37 and 42 respectively. Written reviews are what separate them: 91% of KeyStage's written reviews are positive against 84% of NuRack Auv3 FX Processor's.

UpkeepUpdate frequency

KeyStage ships an update every 3 months, NuRack Auv3 FX Processor every 3 weeks. The most recent releases landed on September 18, 2026 and October 15, 2026 respectively.

Scorecard6 real differences · 5 level
KeyStage versus NuRack Auv3 FX Processor: the parameters behind the verdict, then further details
ParameterKeyStageNuRack Auv3 FX Processor
Price$29.99$7.99 — better
Rating4.7 (37 ratings)4.7 (42 ratings)
Positive reviews91.0% of reviews — better84.4% of reviews
Number of ratings3742 — better
Update frequencyEvery 3 monthsEvery 3 weeks — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchases — betterPaid
Best chart rank—#197 — better
DevicesiPadiPhone, iPad, iPod — better
Requires iOS13.013
Further details — not scored
Size61 MB26 MB
Age rating4+4+
DeveloperAli Gokturk4Pockets.com

Customer experience

KeyStage

All ratings37 ratings
Positive91.9%
Neutral2.7%
Negative5.4%
Written reviews67 reviews
Positive91.0%
Neutral3.0%
Negative6.0%

NuRack Auv3 FX Processor

All ratings42 ratings
Positive92.9%
Neutral2.4%
Negative4.8%
Written reviews32 reviews
Positive84.4%
Neutral6.3%
Negative9.4%

In-app purchases

7 purchases

KeyStage

One-time7
  • Instrument UnitsFree
  • Effect UnitsFree
  • Player, Input, and Mixer UnitsFree
Show 4 more
  • MIDI UnitsFree
  • Small Tip$0.99
  • Medium Tip$3.99
  • Large Tip$9.99
None

NuRack Auv3 FX Processor

No in-app purchases

Questions

Is KeyStage free?
KeyStage costs $29.99, and also offers in-app purchases.
Is NuRack Auv3 FX Processor free?
NuRack Auv3 FX Processor costs $7.99, with no in-app purchases.
Which has better reviews, KeyStage or NuRack Auv3 FX Processor?
KeyStage and NuRack Auv3 FX Processor are both rated 4.7 out of 5 on the App Store, from 37 and 42 ratings respectively.
Do KeyStage or NuRack Auv3 FX Processor have ads?
Neither KeyStage nor NuRack Auv3 FX Processor shows ads.
Which is updated more often, KeyStage or NuRack Auv3 FX Processor?
KeyStage ships an update every 3 months, and NuRack Auv3 FX Processor every 3 weeks. Most recently, KeyStage was updated on September 18, 2026 and NuRack Auv3 FX Processor on October 15, 2026.

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