StepPolyArp 4+

Step Arpeggiator/Sequencer

Laurent Colson

    • 4.7 • 35 Ratings
    • $19.99



"StepPolyArp" is a real-time polyphonic and polyrhythmic MIDI step arpeggiator and step sequencer. It can be used as a standalone application or an AUv3 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, Ableton Link sync, and MIDI clock source sync. An internal sound bank is included.

The AUv3 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 v3 (AUv3) MIDI effect format.

Hosts supporting AUv3 MIDI effect: Logic Pro, Cubasis, Beatmaker, AUM, Audiobus, NanoStudio, Auria Pro, apeMatrix.


• Standalone application and AUv3 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
• Preset sharing support by "AirDrop", "Mail", "Message" and other available services
• Native iCloud support
• "iCloud Drive" support in "Files" app on iOS and in "Finder" on macOS
• Full support of "Split View" and "Slide Over"
• 128 Undo / Redo levels
• Copy and paste
• Lockable keyboard (latch mode)

Supported MIDI connections:

• Virtual "Core MIDI" connections between applications
• Any compatible MIDI interface
• MIDI over Wifi
• MIDI over Bluetooth
• Ableton Link (sync and transport)

What’s New

Version 4.5.1

• Minor bugs fixed

Ratings and Reviews

4.7 out of 5
35 Ratings

35 Ratings

nordical ,


Extremely well made, well thought out app for arpeggios and sequences. This thing handles the bread and butter while opening up possibilities I hadn't even thought of.

Also, I had a support question and the response from the developer was really quick. You get what you pay for folks, and this one's well worth it.

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.

App Privacy

The developer, Laurent Colson, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

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