Features, history, screenshot

Stochas is a previously commercial software that is now open source. If you are an existing customer of Audio Vitamins please be aware that they will no longer be providing support for this product. It is now under the umbrella of the Surge Synth Team, a team of open-source enthusiasts who maintain and support Surge Synthesizer and other open-source tools. Stochas is still actively supported by the original author as well. Please open an issue in the issue tracker.. There is an introductory video that was produced when Stochas was a commercial product that gives a good overview of it.


Stochas is at it’s core a step sequencer, which means it generates MIDI notes. As such it does not generate any sound of it’s own but can be used to sequence other plugins and/or hardware synthesizers. Although it can be used for basic step sequencing, it’s main function is to provide randomness to the step sequencing process. It does this in a few ways:

  • Randomly determine whether a note should be played or not (create more dynamic and varied drum patterns)
  • Randomly choose between two or more notes to play at a specific time (create random or semi-random melodic or drum lines)
  • Add slight timing randomness to notes so that they play slightly before or after their position
  • Add randomness to velocity and length of notes

In addition to the randomness features, it offers a wealth of features:

  • Suitable for both drum and melodic programming
  • Live performance features - Most features can be controlled by MIDI so that you can mute/unmute layers, switch patterns, change timing, transpose notes, etc.
  • Polyrhythms - Create up to 4 simultaneous layers with different time signature, playback speed and/or number of steps per layer.
  • Patterns - switch between patterns during playback for more variety.
  • Timing - Parts can be played at eg half-time or double-time, etc
  • Groove and humanization - Steps can be individually shifted off the grid. Basic swing can be applied, as well as grooves. Grooves can be imported from MIDI files.
  • Chords - quickly select and add chords to your sequence
  • Note customization - Select which MIDI notes are visible in your grid, and even customize the names (useful for drumkits). These customizations can be imported/exported. In addition you can select from standard scales to make it easy to program in melodies.
  • Chain mode allows procedural programming (e.g. “if this note plays/doesn’t play then always/never play this other note”)
  • Record incoming MIDI to the grid
  • Themable interface


Stochas was originally developed as closed source software back in 2016 and was made available for sale by Audio Vitamins. The original idea sprang from a JSFX plugin (Reaper plugin) created by Andrew Shakinovsky called Stochasticizer which allowed semi-random sequencing of melodic and drum lines. Andrew was contacted by Dave Clissold of Audio Vitamins who suggested creating a plugin that would work in any DAW. The two worked together to design the product which was released a few months later. Due to lack of time to devote to marketing a commercial product, in 2020 it was decided to release the software as open source.

stochas screenshot