Apple has released the open source Darwin code for macOS 10.12 Sierra. The code, located on Apple’s open source website, can be accessed via direct link now, although it doesn’t yet appear on the site’s home page. The release builds on a long-standing library of open source code that dates all the way back to OS X 10.0. There, you’ll also find the Open Source Reference Library, developer tools, along with iOS and OS X Server resources. The lowest layers of macOS, including the kernel, BSD portions, and drivers are based mainly on open source technologies, collectively called Darwin. As such, Apple provides download links to the latest versions of these technologies for the open source community to learn and to use.