Auto Fills Drum Fill Generator 4+

Generative AUv3 MIDI Sequencer

Cem Olcay

Designed for iPad

    • 4.6 • 9 Ratings
    • $5.99



Auto Fills is a random MIDI generator app for creating drum fills for your drum synth apps or hardware synthesizers. It works as an Audio Unit AUv3 plugin with the supported host apps such as AUM, Loopy Pro, Logic Pro, Cubasis, Nanostudio, apeMatrix etc.

In Auto Fills, you are working with a drum kit. You can either create the kit by adding drum parts and assigning them MIDI notes/channels yourself, or you can select a kit templete from the settings menu for an app or hardware for quick setup.

- In Kit mode, you can assign a probability value to each drum part.
- In Velocity mode, you can assign a velocity to each drum part, and you can also introduce velocity variety for them.
- In Duration mode, you can set the drum fill length as well as the waiting time before and/or after the drum fill, in beats or bars.
- If you've set "wait before the fill" and/or "wait after the fill" durations in the Duration mode, the drum fill won't be played during the waiting periods.

If you have a favorite drum sequencer, you can route it through the Auto Fills, before the drum app, like
- Drum sequencer -> Auto Fills -> Drum App

And you can block the incoming MIDI from the drum sequencer during the drum fill.
You enable the option in the Duration mode by toggling "block incoming MIDI during the fill" option.
You also have an option for randomizing the drum fill on every cycle.

Assigning probability values is crucial in the Kit mode. If you want to hear a specific drum part mode, just increase it's probability. If you would like to hear a drum part less ofter, just decrease its probability. If you set a probability to zero, it won't play in the drum fill.

- Density knob leaves out notes from the drum if you decrease its value. It introduces rests in the drum fill without regenerating the fill.
- Voices knob sets the maximum number of drum parts can be played at the same time (polyphony). The algorithm chooses a value between 1 and the maximum voice count randomly on every step of the drum fill.
- Rate note sets the speed of the drum fill.
- Generate button lets you regenerate the drum fill. Changing the kit by adding/removing parts, probabilities and voice count also regenerates the fill automatically.

Auto Fills is a MIDI app and it does not produce it's own sound. You need to route Auto Fills MIDI out to an audio app's MIDI input in order to hear the voice.

What’s New

Version 1.4

Adds AU parameters for selecting the mode and controlling the faders.
Fixes Arturia Drumbrute and Drumbrute Impact templates MIDI Channels.

Ratings and Reviews

4.6 out of 5
9 Ratings

9 Ratings

TSD-Randy ,

Cem does it again!

Super useful midi effect! Really comprehensive design. FYI, had to shut down and restart the pad before AUv3 would show up.


Another banger for your system

Great utility in all cem apps!

App Privacy

The developer, Cem Olcay, 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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