TurnKey GNU/Linux is 100% free software (why does this matter?) and by free we mean in the important sense of freedom, not price. Free as in free speech, not free beer.
That means TurnKey is free of hidden backdoors, free from restrictive licensing, and free to use, learn from, modify and distribute.
All TurnKey solutions come with full source code and a powerful self-contained build system that lets you build any image from scratch. You can use an existing solution as a starting point or roll your own.
TurnKey GNU/Linux is Debian with batteries included
TurnKey GNU/Linux is a free software project based very closely on Debian GNU/Linux. Under the hood a TurnKey system image is really just a slightly customized version of Debian that we optimized for a specific usage scenario by carefully pre-integrating a selection of Debian components. This provides users with a starting point that is closer to the end-result they want (i.e., compared with installing Debian from scratch).
Except for a few custom free software components, TurnKey system images are assembled from unmodified Debian binaries straight from the official Debian repositories.
Consequently, the licensing for individual software components included in TurnKey is mostly inherited from Debian.
What is the licensing for Debian GNU/Linux?
Debian is 100% free software. In practice, this means Debian only includes software components licensed under terms that are in compliance with its strict guidelines for what constitutes truly free software. As far as Linux distributions go, Debian is considered a purist as its criteria for licensing is amongst the strictest.
Debian includes free software from a variety of sources that are licensed under a variety of free software licenses. GPL, BSD and the Artistic License are the most common free software licenses in Debian, though there are others as well.
For more information:
What is the licensing for TurnKey's custom components?
Like Debian, TurnKey only includes free software. Custom components not included in Debian are all licensed as free software under terms that satisfy Debian Free Software Guidelines.
Our favorite license is the GPL3, and we default to that for the software we develop especially for TurnKey.
You can determine the license for a package in TurnKey from within the filesystem. Just look under /usr/share/doc/<packagename>/copyright.
You can also determine the license from the debian/copyright file in the source code on GitHub.