Darwin Runtime Engineer, Core OS Cupertino, California, United States Software and Services Summary Posted:

Oct 26, 2026

Weekly Hours:

40

Role Number:

200691491-0836 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. Responsibilities 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 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 Pay & Benefits 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, and can purchase Apple stock at a discount if voluntarily participating in Apple's Employee Stock Purchase Plan. You'll also receive benefits including: Comprehensive medical and dental coverage, retirement benefits, a range of discounted products and free services, and for formal education related to advancing your career at Apple, reimbursement for certain educational expenses — including tuition. Additionally, this role might be eligible for discretionary bonuses or commission payments as well as relocation.

Note:

Apple benefit, compensation and employee stock programs are subject to eligibility requirements and other terms of the applicable plan or program. Apple is an equal opportunity employer that is committed to inclusion and diversity. We seek to promote equal opportunity for all applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, Veteran status, or other legally protected characteristics. At Apple, we believe accessibility is a fundamental human right. You'll find that idea reflected in everything here — in our culture, our benefits and our digital tools. By welcoming as many perspectives as possible, we help you build a career where you feel like you belong. Apple accepts applications to this posting on an ongoing basis.