Twan is an open source separation kernel designed for adaptability, real-time computing, and mixed criticality workloads. Currently, most viable separation kernels are commercial, and those that are open source are typically completely static and are specifically designed to adhere to specifications such as arinc653. Although these standards are essential in highly regulated domains, their strictness often leads to systems which are inflexible, overly complex, or bloated with functionality that is often not required. Some standards will go further and not only describe what guarantees must be provided, but also how they should be implemented.

Twan takes a different approach, rather than directly implementing or adhering to a specific industry specification, twan provides a small policy neutral separation kernel that focuses on strong isolation and deterministic scheduling. Higher level policies such as communication models and health monitoring are to be implemented ontop of the kernel, rather than being hard coded into it.