Jednotlivé programy mají vlastní licence. A na Adrese http://cygwin.com/licensing.html se lze dočíst o "Cygwin API Licensing Terms".
"This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (GPL) as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version."
Podle mne to je jasné přihlášení se k GPL.