The code and documentation in the repositories of the seL4 GitHub organisation are available under standard open-source licenses, identified by SPDX license tags.

The seL4 Foundation licenses and accepts contributions for

Note that, as in the Linux syscall note for the GPL, the seL4 kernel GPL license does not cover user-level code that uses kernel services by normal system calls - this is merely considered normal use of the kernel, and does not fall under the heading of “derived work”. Syscall headers are provided under BSD.

For a longer explanation of how the seL4 license does or does not affect your own code see also this blog post.

The repositories of the seL4 GitHub organisation also contain third-party code under additional compatible open source licenses. See the individual file headers for details, or use one of the publicly available SPDX tools to generate a software bill of materials. The directory LICENSES/ in each repository contains the text for all licenses that are mentioned by files in that repository.