"StepPolyArp Unit" is a real-time polyphonic and polyrhythmic MIDI step arpeggiator and step sequencer. It can be used as a standalone application or an Audio Unit MIDI effect plug-in.

The application and the plug-in can operate as a step arpeggiator by automatically generating melodic patterns from played notes or chords, or as a step sequencer that doesn't require MIDI input to play.

Unlimited presets can be saved on a local device and synchronized to iCloud. Each preset contains 16 patterns, 5 customizable polyrhythmic step controllers, and a 32 steps event matrix with 11 polyphonic and polyrhythmic lines driving the arpeggiator engine.

The application supports full internal and external MIDI connections for input and output, Audiobus MIDI sender, MIDI filter routing, Ableton Link sync, and MIDI clock source sync. An internal sound bank is included.

The Audio Unit MIDI effect plug-in supports multiple instances. A compatible host is required to run the plug-in. The host needs to support the Audio Unit MIDI effect format.


• Standalone application and Audio Unit MIDI effect plug-in
• Arpeggiator and step sequencer mode
• 1 to 32 steps programmable matrix
• 11 configurable transposition lines
• Polyrhythmic lines
• 16 patterns by preset
• Automatic chaining patterns
• 8 octaves resizable keyboard
• Multitasking
• Sample-accurate timing
• Internal sound bank
• Tap tempo
• Receiving MIDI from external MIDI sources
• Receiving external MIDI sync (MIDI clock)
• Ableton Link support
• Internal routing of inputs, outputs, and MIDI sync
• Send MIDI to a virtual port that can be used as MIDI input by other "Core MIDI" compatible applications
• Default velocity, modulation, pan, volume, aftertouch, and pitch bend steps controller
• Customizable steps controller MIDI setup
• Arpeggiator and sequencer conform to the selected scale
• 6 arpeggiator modes
• 1 random mode
• 1 chord mode
• Random patterns creation
• Presets manager
• "Program Change" support
• Native iCloud support
• "Files" application support
• Full support of "Split View" and "Slide Over"
• 128 Undo / Redo levels
• Copy and paste
• Lockable keyboard (latch mode)

Compatible hosts supporting Audio Unit MIDI effect:

• Cubasis
• Audiobus
• BeatMaker
• apeMatrix

Supported MIDI connections:

• Virtual "Core MIDI" connections between applications
• iOS compatible MIDI interface
• MIDI over Wifi
• MIDI over Bluetooth
• Ableton Link (sync and transport)
• Audiobus (MIDI, transport, state saving)


An iPad or iPhone with iOS 11 or later


What’s New

Version 4.1.6

• Added support for new iPad Pro "all-screen design"
• Minor bugs fixed

Ratings and Reviews

4.9 out of 5
11 Ratings
11 Ratings
LJ Swype ,


I love sound design and mixing, but I am not a musician. By using midi song kits I have been able to find new arrangements to mix, but it can be an expensive endeavor. This app, along with Odesi (for chords, bass, and drum midi), let’s me generate pitch perfect midi tracks in seconds, which I can then voice with the synth of my choice and mix to taste in Cubasis. Thank you to the dev! 🙏🏾

MIchael Trigoboff ,

Great Arpeggiator!

Capable of doing just about anything you can think of. Integrates perfectly with Cubasis.

There’s a bit of a learning curve to climb, but the results are worth it. Make sure to read the manual. Tech support is very quick via email from the author of the software.

grape_ape_grape_ape ,


A highly versatile MIDI controller that takes advantage of the ability to use MIDI FX that was introduced in iOS 11, meaning you can use it in host apps like Cubasis and AUM. One of the better apps for music making on iOS.


Laurent Colson
30.8 MB
Requires iOS 11.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© Laurent Colson


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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