Darwin Runtime Engineer, Core OS
Confirmed on the employer's own hiring board on Oct 28, 2026. First seen by Alion on Oct 26, 2026. Apple scores A on the Alion truth index.
For the engineer who obsesses over the butterfly effect of a single line of code, there is no greater stage than Apple's Core OS! Core OS builds uncompromising, lightning-fast foundation that iOS, macOS, watchOS, tvOS, and visionOS stand upon. We don't just write software; we forge the soul of the machine, ensuring the operating system and the hardware breathe as one to create a seamless device identity.
At the center of it all is Darwin, the UNIX-like heartbeat of Apple's operating systems, spanning from the deepest levels of the kernel up through critical low-level user components. The Darwin Runtime team is seeking visionary engineers to push the boundaries of low-level system technologies. If you obsess over performance, security, and the massive cascading impact of your code, your life's best work is waiting for you here!
Description
The Darwin Runtime team is responsible for the development and evolution of low-level user space libraries such as Grand Central Dispatch (GCD), Inter-Process Communication (IPC) technologies like XPC, pthread, and malloc, among others. The foundational libraries built by our team are the invisible engines powering the iPhone, iPad, Mac, Apple Watch, Apple TV, and the groundbreaking Vision Pro. We want an engineer with the drive to operate autonomously, the hunger to master new domains, and the ambition to step into technical leadership. Here, your voice shapes the future. You will drive critical design discussions, elevate peers through code reviews, and push the boundaries across a spectrum of technologies. Our environment fosters a culture of deep technical innovation, massive autonomy, and true ownership.
Minimum Qualifications
Passion for low-level system technologies
Fluency in the C programming language
6+ years of Experience with UNIX-like systems
System design and architecture skills
Strong understanding of operating system fundamentals like threading, synchronization primitives, inter-process communication, scheduling, and virtual memory
Excellent collaborative skills, with the ability to work with a team to design system architecture
BS or MS in Computer Science or equivalent degree
Preferred Qualifications
Knowledge of operating system implementation, hardware architecture and assembly programming
Knowledge of Swift or Objective-C
Skilled at interface and/or API design
Experience with lldb or gdb
Experience using Gen AI tools for Software Development