NetBSD
The NetBSD Project is a free, secure, and highly portable Unix-like Open Source operating system available for many platforms, from large-scale server systems to powerful desktop systems to handheld and embedded devices.
It's clean design and advanced features make it excellent in both production and research environments, and the source code is freely available under a business-friendly license.
We have greatly expanded the NetBSD items in 2023: new t-shirts, mugs, caps...Collaborating from 2009, the link between FreeWear.org and The NetBSD Project is powerful. FreeWear donate a portion of the sales of NetBSD materials in this website.
Donations accumulated until 2022/12: 183.45 € (VAT included)
More information: http://www.netbsd.org/