A Musical Experiment

FretPet was originally conceived as a tool to build chords from scales, visualize chords on the guitar fretboard, calculate chord names, and perform chord operations like transposing keys and harmonizing scales. It still retains all these functions, which you can access without creating a document:

  • See the functions of the tones in a chord
  • Find all 12 names for any chord
  • Find fingerings for any chord in any guitar tuning
  • Transpose and harmonize chords interactively
  • View chord fingering diagrams

Central to the original intent of the program was to come up with new ways of presenting chords, tones, and musical connections using visual analogies. The Chord Circle, for example, displays the tones of a chord in a manner that makes harmonic patterns more obvious.


FretPet has grown from its humble beginnings into a powerful MIDI controller and music composition tool. You can save the chords you build in a progression, apply picking patterns, and play them out to any of your favorite synthesizers, including software synthesizers like GarageBand, Absynth, SimpleSynth, and many others. Using software like MidiPipe you can modify the MIDI stream to insert unusual musical effects on the way to your favorite synth.

  • Build chord progressions around keys and modes
  • Store your favorite picking patterns
  • Play through the QuickTime™ synthesizer and CoreMIDI
  • Play through any hardware or software synthesizer


One of my main criteria when creating FretPet was that all the visual elements of the program should be as interactive as possible. So virtually everything in FretPet can be clicked on, even during playback. The net result is that you can hear your compositional ideas evolve dynamically and make meaningful choices during improvisation.

Utility or Toy?

More than anything FretPet is meant to be fun and to bring an element of playfulness and unpredictability to the creative process. Amazing results come from messing around with FretPet while GarageBand and other synthesizer programs play and record your experiments. While FretPet can be very useful in getting to know your guitar and composing tight chord progressions, I've found that the best results come from taking a playful approach. So have fun!