Sr. Staff Software Engineer, Browser (New Products)

Accountabilities: Design and implement experiments across browser engine subsystems, investigating how internal data structures and execution behavior influence performance, correctness, and the information available to developer tools. Evaluate approaches for representing and exposing browser state efficiently and accurately, assessing trade-offs involving information loss, implementation complexity, and compatibility with dynamic web content. Prototype browser engine capabilities that enable reliable programmatic interaction with websites, accounting for document structure, layout, navigation, and event handling. Instrument browser behavior and evaluate new implementations through repeatable tasks, measuring performance and correctness while isolating the impact of individual changes. Document unsuccessful experiments as carefully as successful ones, validate findings across different workloads, and determine whether improvements generalize beyond the conditions used during development. Profile the overhead introduced by new capabilities and optimize performance when supported by measurement and evidence. Use AI-assisted coding and analysis tools to accelerate experimentation while validating their output through debugging, testing, and reproducible measurements. Collaborate with the technical lead and other specialists to investigate unfamiliar systems, assess technical trade-offs, and inform the direction of new browser-based products. Requirements: Extensive hands-on experience with at least one browser engine subsystem, such as the Document Object Model (DOM) and Web APIs, layout and rendering, accessibility, JavaScript runtimes, networking, or process architecture, including substantial implementation work and an understanding of related subsystems. Strong proficiency in C++ or Rust , with experience navigating large systems codebases and practical knowledge of memory ownership, concurrency, object lifetimes, and performance debugging. Ability to develop JavaScript and scripting tools to exercise browser behavior, automate tests, and collect reliable measurements. Demonstrated ability to investigate unfamiliar code, formulate precise hypotheses, build effective prototypes, and interpret results while distinguishing implementation effects from variations in websites, workloads, or model behavior. Strong understanding of web platform behavior and compatibility, including the relationships between document structure, script execution, rendering, navigation, and user interaction. Experience with profiling, tracing, regression testing, or conformance testing, supported by a disciplined approach to reproducible evidence and performance evaluation. Ability to explain the benefits and limitations of technical optimizations, including the conditions under which an approach may fail. Curiosity about AI agents and a willingness to work directly with agent harnesses and coding tools, connecting low-level browser implementation decisions to the information agents receive and the actions they can perform. Strong analytical thinking, technical independence, and a practical, experimental mindset suited to solving complex engineering problems. Nice to have: Contributions to Gecko, Servo, Blink, WebKit, or another browser engine; experience maintaining open-source projects; technical leadership in a small team developing a new product; or experience in accessibility infrastructure, browser security, profiling, and automated evaluation of AI agent workflows. Benefits: Competitive annual salary in Canada: Canada Tier 1 locations: CAD $165,000–$220,000 . Canada Tier 2 locations: CAD $149,000–$199,000 . Performance-based bonus plans for eligible employees. Comprehensive medical, dental, and vision coverage. Generous retirement contributions with 100% immediate vesting , regardless of employee contributions. Quarterly company-wide wellness days to support rest and well-being. Country-specific public holidays, plus a day off for your birthday. One-time home office stipend. Annual professional development budget. Quarterly well-being stipend. Substantial paid parental leave. Employee referral bonus program. Additional benefits, which may include life and accidental death and dismemberment insurance, disability coverage, and an Employee Assistance Program, depending on the country. Remote work opportunity within Canada.