Spatterlight is released under the GNU Public License; the interpreters and libraries it uses under the hood are freely redistributable and covered by their own specific licenses.

AdvSys 1.2 by David Betz.
Agility 1.1.1 by Robert Masenten.
Alan 2.8.6 / 3.0a3 by Thomas Nilsson.
Frotz 2.43 by Stefan Jokisch and others.
Git 1.1.0 by Iain Merrick.
Hugo 3.1 by Kent Tessman.
Level9 4.0 by Glen Summers, David Kinder, Alan Staniforth, Simon Baldwin and Dieter Baron.
Magnetic 2.2 by Niclas Karlsson, David Kinder, Stefan Meier and Paul David.
Scare 1.3.3 by Simon Baldwin and Mark J. Tilford.
TADS 2.5.9 / 3.0.9 by Michael J. Roberts.
UnQuill 0.8.5 by John Elliott.

Glk 0.7.0 (draft) by Andrew Plotkin.
Babel 0.2b by L. Ross Raszewski.
FMOD by Firelight Technologies Pty, Ltd.

http://ccxvii.net/spatterlight