Period Seq is a simple algorithmic MIDI generator that applies four counters to two clocks and four reset rates. It can produce non-repeating or complex, structured feeling sequences automatically. The GUI is designed for applying performance variations in use.

Each counter normally creates MIDI notes at a regular periodic interval after being reset. Counters can be used to reset other counters, so that modulating the selection of clocks and reset rates applied to each counter can produce complex variation in the output. LFOs can also be reset periodically for sequencing contour effects.

Period Seq is appropriate for experimental applications and sequencing percussion.