Wikipedia
SynthEdit is a shareware Windows application which uses a modular VPL (Visual Programming Language) to create music synthesizers and effects units. These can then be compiled as VST plug-ins for use in audio applications. SynthEdit first released in 1999 by Jef McClintock, and version 1.0 was released on 23 June 2005. Many programmers have since created additional freeware and payware modules for use within SynthEdit's programming environment.
SynthEdit can export creations to VST format.
SynthEdit allows users to create VST Instruments and VST Effects. It provides a GUI editing system and full MIDI interface for hardware controllers. SynthEdit has also been used to create additional devices that do not fall within the realms of synthesizer or effect units.
Audio and MIDI plug-ins for SynthEdit can be written in C or C++ using the SynthEdit Music Plugin Standard (SEM) API, which is based on GMPI with some extensions. 1