Sr. WebKit Performance Engineer
Apple
San Diego, CA, USA
USD 171,600-302,200 / year + Equity
Posted on Mar 31, 2026
The WebKit Performance team is looking for an engineer with a passion for software optimization to support one of the most heavily used frameworks and applications in the world. WebKit is the system framework for rendering web content on Apple platforms. When you load a webpage in Safari, that’s WebKit! WebKit is also an Open Source software project in which Apple engineers collaborate with engineers from around the world to improve the framework, evolve web APIs, and ensure the best possible experience on the web. WebKit is a foundational component of iOS, macOS, watchOS, tvOS, and visionOS, forming the basis of many key applications. Performance improvements in WebKit make all of our products better. The WebKit Performance team is responsible for defending and improving the launch speed, processing speed, memory size, and power consumption of the WebKit framework. You will help improve WebKit performance on all Apple platforms.
As a WebKit Performance Engineer, you will seek opportunities to improve WebKit performance as measured by execution time, memory consumption, and power use. You will also be responsible for diagnosing performance issues identified in benchmarks and in web applications, helping us identify and correct recent performance regressions, and helping to train and mentor others in performance improvement techniques. Specific job duties will include: * Investigating cases of poor performance in WebKit-based applications Identifying performance bottlenecks and hot-spots in the WebKit framework. * Creating and defending performance benchmarks covering important web technologies. * Working across teams at Apple to drive improvements in core frameworks. * Interacting with developers on the Open Source WebKit project.
- Designing and maintaining the on-device architecture that stores, vends, and syncs Messages data across iOS, macOS, watchOS, and visionOS.
- Developing robust data structures, APIs, and database schemas to support innovative new Messages features.
- Building and optimizing sync infrastructure, specifically focusing on Messages in iCloud and CloudKit integration.
- Managing system daemons, attachment storage, and transcoding pipelines.
- Creating testable code to rigorously test changes and ensure consistent quality and backwards compatibility over time.
- Collaborating with cross-functional teams—including peer engineers on protocols, security, platform API, and user experience—to build exciting new features.
- BS in Computer Science or equivalent work experience.
- Expertise in C++.
- Experience with software performance measurement, analysis, and optimization.
- Detailed understanding of data structures and algorithms.
- Experience with pointers, memory management, threads, and processes.
- At least 4 years of prior hands-on iOS or macOS application development.
- Experience with Objective-C, Swift, and Cocoa APIs.
- Experience with web technologies (HTML, CSS, JavaScript, SVG, WebGL, WebGPU).
- Experience with UIKit and AppKit.
- Excellent debugging, analysis, communication, and critical thinking skills.
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. Learn more about your EEO rights as an applicant.