JSyn - modular synthesis API for Java.
JMSL - Java Music Specification Language
PortAudio - cross platform audio I/O API for 'C'


You can now download the complete MIDI 1.0 specification from the MMA as a PDF! This document was not available to the public until 2016.

Download the MIDI 1.0 Specification - look near the bottom of this page.

Historically interesting links: