WINDOWS OS 32 bits: setup32-jniz-2-x-x.exe
WINDOWS OS 64 bits: setup64-jniz-2-x-x.exe (solver up to 3x faster)
Linux: jniz.tar.gz (uncompress & run jniz.sh in a terminal)
OS X: Jniz.dmg
Midi input with keyboard explained in the Jniz doc: http://www.jniz.org/doc/howto.pdf
You can also run Jniz with the jniz.jnlp file directly from your browser thanks to the Java Web Start (JRE must be installed in your device).