Polymeter is a specialized MIDI sequencer for composing music in polymeter, meaning music that uses multiple meters simultaneously. The application doesn't generate audio directly, instead it outputs a stream of MIDI messages to a device that converts MIDI to audio, such as a hardware or software synthesizer. By default, the application outputs to the GS Wavetable Synth that ships with Windows. The application also exports a Standard MIDI file that can be imported into most music software.
A Polymeter document consists of an array of tracks, each of which produces a single MIDI note or control message at a time. Each track has its own length and loops independently through its own array of equal-sized steps. For note tracks, the steps determine the starting times, durations, and velocities of notes, but steps are interpreted differently for other track types. Tracks of differing lengths can be juxtaposed, and then edited while they're looping. Tracks can also modulate other tracks, and can be arranged into songs.
The application features multiple views, corresponding to different stages of the composing process, and various docking windows. Most application parameters can be remotely controlled by mapping them to MIDI messages.