Darwin Runtime Engineer, Core OS

Cupertino, California, United States Software and Services

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!

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.

• Design and implement new features and APIs for Darwin Runtime technologies like GCD, XPC, pthread, and malloc, among others
• Develop and maintain high-performance runtime libraries that handle memory management, and component lifecycle across different execution environments
• Optimize code generation, runtime performance, and memory usage to meet strict performance requirements for low-level systems
• Participate in all phases of software development cycle: from problem definition and design, through implementation, testing, and debugging
• Diagnose and resolve issues across different layers of the stack
• Write unit and integration tests for new and existing code
• Work with cross functional teams to enable developer and product requirements

• 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

• 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

At Apple, base pay is one part of our total compensation package and is determined within a range. This provides the opportunity to progress as you grow and develop within a role. The base pay range for this role is between $150,400 and $277,600, and your base pay will depend on your skills, qualifications, experience, and location.

Apple employees also have the opportunity to become an Apple shareholder through participation in Apple’s discretionary employee stock programs. Apple employees are eligible for discretionary restricted stock unit awards,…