WretchUp vs In Theory
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
WretchUp
This app offers a unique audio manipulation experience, allowing users to create sonic mayhem with pitch-shifted delays, filters, and sampling. It's designed for live performance and studio use, enabling musicians and sound enthusiasts to generate wild noises and unique effects.
- Pitch-shifted delay with feedback and filter
- Live performance-oriented controls
- Gesture-based play
- Record vocals and instruments
- Sample and manipulate loops
- Inter-App-Audio and Audiobus support
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An effect instrument anyone can play - sonic anarchy in the palm of your hand. iOS Mars: "Barely controlled chaos“, "sonic extremes“, "well suited for live use“ Music App Blog: "if you like the occasional dose of sonic mayhem, then this is an app that will let you make it" WretchUp is the sonic instrument from the imagination of Mouse on Mars Instruments. Used by the duo in their live performances, it's a playable effect inspired by analog hardware. Sing into it, speak into it, plug in an instrument, sample sounds, and then make sonic mayhem. It's been tested in Mouse on Mars' live shows and used in studio albums. But now it's available to anyone - whether you're a musician wanting to create unique sounds or you just want to make some wild noises and frighten friends and enemies. // FEATURES - Pitch-shifted delay with feedback and filter - Unique controls, designed to be used in live performance and tested onstage - Play with gestures, even without looking closely at the screen - Record vocals or instruments from the built-in mic or another input - Sample loops and change their speed - Adjust the feedback loop, pitch, and filter for unique sounds - Make inputs by holding down your finger, or lock input for continuous sampling - Inter-App-Audio supported - Audiobus supported www.mouseonmars.com/mominstruments Features artwork by Rupert Smyth. Pure Data-based, open source patch created by Florian Grote and Peter Kirn with Mouse on Mars. App design by Oliver Greschke. Powered by free and open source software libpd. Note: like all mic-based effects, you need to enable microphone input. If you accidentally did not allow mic input, you can allow later via: Device settings, WretchUp, Data settings, Microphone, allow mic input.
In Theory
This app provides a unique interval-based MIDI keyboard with over 110 scales. It allows for flexible chord creation by toggling additional intervals and notes from different octaves. It integrates with external MIDI keyboards and sequencers for advanced music production.
- Interval-based MIDI keyboard
- Over 110 built-in scales
- Customizable chord voicing
- MIDI keyboard input support
- MIDI CC message control
- AUv3 plugin compatibility
- Visual scale and note display
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In Theory is an interval based MIDI keyboard app with more than 110 scales. It has a keypad at the bottom with the interval buttons like +2, +1, 0, -1, -2 which would change the current note. Zero means the current note, +1 means the note after the current note, +2 means two notes after the current note, -2 means two notes before the current note in the scale and so on. Above the keypad, you can toggle additional intervals in the scale for creating chord voices. You can also select the notes from an octave above and an octave below for creating rich, extended chords. You can use your MIDI keyboard to play In Theory as well. The middle C4 key on your MIDI keyboard triggers the 0 (zero) button on the app's keypad. The white notes after the C4 note would trigger the positive buttons, the white notes before the C4 note would trigger the negative notes on the keypad. You can also toggle the chord intervals with MIDI CC messages. You can set a MIDI CC number and a MIDI Channel for toggling the chord intervals from the settings menu. If you send a MIDI CC value between 0-62, you can toggle the chord intervals respectively. With the MIDI capabilities, you can also sequence the app with a MIDI sequencer app like PolyBud, ShiftBud, MelodyBud etc. In Theory has more than 110 scales built-in. You can also use the custom scales you made in ScaleBud 2 app as well. The key and scale could be changed externally from a MIDI controller in AUv3 plugin with the AU parameters. The circular display on the UI will show you where you are in the scale. Also, when you play a note, you will see the every playing note on the screen with the root note and the chord intervals. Please note that In Theory is a MIDI app and does not produce any kind of sound on its own. You need to connect the MIDI output of the app to an audio app's MIDI input. For the AUv3 plugin you'll need an AUv3 host app such as AUM, Cubase, Nanostudio, apeMatrix etc.
Screenshots
Verdict
The clearest difference is rating: In Theory at 5.0 against WretchUp's 3.1. In Theory also leads on update cadence (weekly vs every 3 weeks) and review sentiment (100% vs 91%). WretchUp's advantage is iOS requirement (11.0 vs 13.0). On price, ratings volume, ads and in-app purchases 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
WretchUp costs $4.99 and In Theory $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
In Theory holds the better App Store score, 5.0 against 3.1. Both are backed by a comparable volume of ratings — 9 and 4 respectively. Written reviews point the same way: 91% of WretchUp's written reviews are positive against 100% of In Theory's.
WretchUp ships an update every 3 weeks, In Theory weekly. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.
| Parameter | WretchUp | In Theory |
|---|---|---|
| Price | $4.99 | $4.99 |
| Rating | 3.1 (9 ratings) | 5.0 (4 ratings) — better |
| Positive reviews | 90.9% of reviews | 100.0% of reviews — better |
| Number of ratings | 9 — better | 4 |
| Update frequency | Every 3 weeks | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 11.0 — better | 13.0 |
| Further details — not scored | ||
| Size | 15 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | MoMinstruments GbR | Cem Olcay |
Customer experience
WretchUp
In Theory
In-app purchases
WretchUp
No in-app purchases
In Theory
No in-app purchases









