harmonySEQ –  A MIDI sequencing application helpful for music composers and live artists.

harmonySEQ is a MIDI sequencer for Linux. Basically, it does what any sequencer do – it playbacks a sequence of notes. However, it is slightly different from most of the popular software sequencers.


harmonySEQ allows you to create any number of sequencers. All sequencers keep repeating their melody that is bound to them. You can set the tempo globally, that means that every time each sequencer repeats his sequence with the same tempo as the others do. This keeps them synchronized!

Sequences may have very complex patterns – notes may be of different length and velocity, all thanks to a simple yet full-featured piano-roll interface. Moveover, you can bind many melodies to one sequencer, and it will play only the active one. You can choose which is active, both using the GUI or by triggering the change by pressing a key on your keyboard, or using a MIDI controller.

harmonySEQ can easily cope with very complex polyrhythms, which is an original feature. You can achieve that by selecting different time signatures for each sequencer. Most software sequencers get easily confused, if simultaneously played melodies are – for example – in 3/4 and 4/5. harmonySEQ easily deals with this problem, and will automatically synchronize these melodies for you.

You can set each sequencer not only a sequence, but also the base chord, from which notes are chosen when playing the sequence. This way all sequencers can be easily tuned to each other, and the resulting sound will consist only of notes that sound great together.

There is one more feature that makes harmonySEQ unique – the Events&Actions system. You can set how harmonySEQ should react on triggers like key press, MIDI note on, etc. Those events may cause effects (actions), such as toggling some sequencers on/off, transposing the melody, changing the tempo, or changing chords or active melodies of the sequencers etc. This way you can quickly choose active sequencers, and adjust the harmonySEQ‘s melody properties, pressing just one key, so that you f.e. do not need to pause playing the main-line melody – which makes harmonySEQ interesting for live performances.

harmonySEQ also has so-called control sequencers, that output MIDI controller events instead of notes. You can design their pattern by editing it’s plot, which is clear and intuitive, and the resulting output will be always in-sync. Synchronizing effects and melody has never been that simple!

If you still have doubts what harmonySEQ is, look at the screenshots, read the FAQ, or visit the showcase section.

harmonySEQ is distributed under the terms of the GNU General Public License. It’s Free Software, so you can freely use, distribute and modify it as you wish.

harmonySEQ works only on Linux. Other operating systems, like Windows, are not considered due to inconvenient MIDI interface. More details can be found on the downloads page.

A list of features consists of :

  • Any number of synchronized sequencers
  • Each can play different pattern of notes to different MIDI channels
  • Melodies/patterns may have unequal lengths and resolutions, but they will still be synchronized
  • Complex polyrhythms are fully supported
  • Sequencers use only notes from the chord that is bound to them, which makes it easy to keep them in tune
  • Transposing, muting, changing chords and changing melodies can be done on the go, during the performance.
  • Heavily customizable events-actions system, which one may use to make harmonySEQ react on events like keypress, noteon, etc.
  • Control sequencers that allow to synchronize effects with melody
  • Saving and loading sequencer sets to files
  • OSC support
  • Tiny CPU usage
  • Multilingual GUI, (currently English, Polish, German and Japanese)
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