FMMF is a 4-operator FM synthesizer designed to provide deep sound design capabilities through intuitive graphical interfaces. It features multiple waveforms and algorithms displayed visually, allowing precise control over sound shaping. The envelopes are highly customizable with drag-and-drop nodes, adjustable contours, and support for multiple stages, sustain points, and tempo synchronization. These envelopes modulate volume, pitch, and effects, offering velocity and key tracking for expressive performance.

Beyond its core FM synthesis engine, FMMF includes a resonant low-pass filter, a multi-mode distortion unit, and a flexible delay effect with comb delay options, all modulated by envelopes and LFOs. The synthesizer incorporates several LFOs with a variety of waveforms, including randomizing shapes, and each LFO features its own ADSR envelope. An arpeggiator with multiple modes and tempo-sync options adds rhythmic complexity, making it easier to craft evolving sequences and dynamic textures.

The preset collection showcases a broad range of sounds, from atmospheric pads and expressive leads to rich basses and quirky sound effects, demonstrating the instrument's wide sonic palette. Adjustable polyphony, portamento, and harmonic controls further enhance its flexibility. Created with sound design in mind, FMMF enables musicians and producers to explore complex FM synthesis with ease and creativity.