The Darwin Runtime team in Core OS is looking for enthusiastic engineers interested in developing low-level system technologies for Apple’s operating systems. Darwin is the UNIX-like foundation at the heart of all Apple’s operating systems, stretching from the kernel up through low-level user components. The Darwin Runtime team is responsible for building the low-level user space runtime technologies like Grand Central Dispatch (GCD), inter-process communication systems, memory allocator, threading library, and concurrency and synchronization primitives. Other than being the foundation for iOS and macOS frameworks and applications, these technologies are deeply integrated into the Swift programming language to guarantee robust and high performant primitives built from the ground up. The ideal candidate should be self-motivated and effective in operating independently, with a desire to learn and develop technical leadership. Team members are welcome and encouraged to participate in design discussions, code reviews, and development across multiple technologies. Our environment fosters technical innovation, meaningful technology ownership, and a liberating amount of autonomy!