mKer vs In Theory
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
mKer
A versatile MIDI step sequencer designed for music creation. It offers multiple outputs, extensive pattern and lane customization, and advanced step editing. Best used within an AUv3 host app for sound generation.
- 8 MIDI outputs
- 64 Patterns with 16 Lanes each
- Customizable Steps and Step Size per Lane
- Advanced Step Parameters (Pitch, Velocity, Probability, etc.)
- Flexible Editor with Step Entry Keyboard
- 32 Clips with Repeat Functionality
- Performance Tab with Assignable Sliders and Morphing
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*** Note *** Although mKer can run as a stand-alone app, the recommended way to use it is as an AUv3 plugin from inside a suitable AU Host app that supports MIDI Processors such as AUM, Audiobus, Cubasis etc. Please also note that mKer is a MIDI app/plugin. That means that it does not produce sound itself - it needs to be connected to an audio source that can receive MIDI. mKer is a versatile, multi-output MIDI step sequencer with an extensive range of features. These include: - 8 MIDI outputs - 64 Patterns - 16 Lanes (aka tracks) per Pattern - Independent number of Steps (1-32) and Step Size (1/64-256 beats) per Lane per Pattern - Every step can play either a single note, an interval (2 notes) or a chord (3 or 4 notes) - Lane Step parameters: Play Cycles, Skip Cycles, Play Offset Cycles, Pitch, Velocity, Probability, Offset (can be used for ‘swing’ like effects), Repeat (rachet) and Gate - A flexible Editor that includes a step entry keyboard, parameter sliders and a variety of options and utilities designed for to make the workflow intuitive and fast - 32 Clips with 1-8 Steps per Clip, 1-128 repeats per step (every clip step has one pattern) - 3 Play Modes: Pattern, Clip, Sequence (all Clips) - A Performance tab with 10 fully assignable MIDI sliders, a 12-snapshot bank and morphing function between the snapshots... - MIDI step input and real-time recording - 12-track beat generator with six genres, density, intensity and GM beat mapping ... and more!
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 review sentiment: In Theory at 100% against mKer's 64%. In Theory also leads on rating (5.0 vs 4.5) and update cadence (weekly vs every 3 weeks). mKer's advantage is ratings volume (22 vs 4) and price ($3.99 vs $4.99). On ads, in-app purchases, monetization model 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
mKer costs $3.99 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 4.5. That said, the two scores are not equally well evidenced: mKer has 22 ratings behind it against 4, so its average is the more settled of the two. Written reviews point the same way: 64% of mKer's written reviews are positive against 100% of In Theory's.
mKer ships an update every 3 weeks, In Theory weekly. The most recent releases landed on October 23, 2026 and October 24, 2026 respectively.
| Parameter | mKer | In Theory |
|---|---|---|
| Price | $3.99 — better | $4.99 |
| Rating | 4.5 (22 ratings) | 5.0 (4 ratings) — better |
| Positive reviews | 63.6% of reviews | 100.0% of reviews — better |
| Number of ratings | 22 — better | 4 |
| Update frequency | Every 3 weeks | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPad | iPhone, iPad, iPod — better |
| Requires iOS | 13.0 | 13.0 |
| Further details — not scored | ||
| Size | 57 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | Axart Labs OU | Cem Olcay |
Customer experience
mKer
In Theory
In-app purchases
mKer
No in-app purchases
In Theory
No in-app purchases









