FluidSynth, formerly named iiwusynth, is a free open source software synthesizer which converts Musical Instrument Digital Interface (MIDI) note data into an audio signal using SoundFont technology without need for a SoundFont-compatible soundcard. FluidSynth can act as a virtual MIDI device, able to receive MIDI data from any program and transform it into audio on-the-fly. It can also read in SMF (.mid) files directly.