Staff Software Engineer, Browser (New Products)
Level inferred from job title
Job description
Experienced browser engineer joining a small team exploring new applications of browser technology, investigating browser behavior and implementing changes deep in the engine. A hands-on individual contributor role owning engine-level investigations and implementation, working closely with the team's technical lead.
At a glance
- Employment
- Full-time · Employee (employment agreement)
- Work mode
- Remote · Canada
- Pay
- CAD 145,000 – 170,000 / year
What you'll do
- Design and implement experiments within browser engine subsystems; investigate how internal data structures and execution behavior affect performance, correctness, and the interfaces exposed to developer tools
- Evaluate ways to represent and expose browser state efficiently and accurately, identifying tradeoffs including information loss, implementation complexity, and compatibility with dynamic web content
- Prototype engine capabilities that support reliable programmatic interaction with web content; investigate how document structure, layout, navigation, and event handling affect correctness and performance
- Instrument browser behavior and evaluate changes against repeatable tasks; measure performance and correctness, isolate the effect of each change, and document unsuccessful experiments as clearly as successful ones; check that gains hold beyond the workloads used to develop the prototype
- Profile the overhead introduced by new capabilities and pursue improvements where measurements justify them; use AI tools to accelerate coding and analysis and verify their output through debugging, tests, and measurement
What we're looking for
- Deep hands-on expertise in at least one browser engine subsystem, such as DOM and Web APIs, layout and rendering, accessibility, JavaScript runtimes, or networking and process architecture; has implemented substantial changes and can trace their effects into neighboring subsystems
- Strong proficiency in C++ or Rust, experience navigating a large systems codebase, and practical knowledge of memory ownership, concurrency, object lifetimes, and performance debugging; can build the JavaScript and scripting tools needed to exercise and measure work
- Demonstrated ability to investigate unfamiliar code, form a precise hypothesis, construct a useful prototype, and interpret the results; can separate the effects of the implementation from variability in websites, workloads, or model behavior
- Strong understanding of web platform behavior and compatibility; can reason about how document structure, script execution, rendering, and user interaction relate, including cases where the browser's internal state is difficult to expose accurately to another system
- Experience with profiling, tracing, regression tests, or conformance tests, and a habit of grounding performance claims in reproducible evidence; can explain both the benefit of an optimization and the circumstances in which it fails
- Curiosity about AI agents and a willingness to work directly with agent harnesses and coding tools; can connect a low-level implementation choice to the information an agent receives and the work it must do next
Nice to have
- Contributions to Gecko, Servo, Blink, WebKit, or another browser engine
- Experience maintaining an open-source project
- Technical leadership in a small team building a new product
- Experience with accessibility infrastructure, browser security, profiling, or automated evaluation of agent workflows
Benefits
- Generous performance-based bonus plans to all eligible employees
- Rich medical, dental, and vision coverage
- Generous retirement contributions with 100% immediate vesting (regardless of whether you contribute)
- Quarterly all-company wellness days where everyone takes a pause together
- Country specific holidays plus a day off for your birthday
- One-time home office stipend
- Annual professional development budget
- Quarterly well-being stipend
- Considerable paid parental leave
- Employee referral bonus program
- Other benefits (life/AD&D, disability, EAP, etc. - varies by country)
Apply
Direct apply at Mozilla
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About Mozilla
The non-profit-backed technology company that has shaped the internet for the better over the last 25 years
Mozilla Corporation is the non-profit-backed technology company behind brands like Firefox, the privacy-minded web browser. With more than 225 million people around the world using its products each month, Mozilla works on diverse areas including AI, social media, security and more. The Mozilla Corporation is wholly owned by the non-profit 501(c) Mozilla Foundation, so it isn't beholden to any shareholders — only to its mission.
Mission
To make the internet better for people; to build the Internet as a public resource accessible to all because open and free is better than closed and controlled
Key facts
- More than 225 million people around the world use Mozilla products each month
- The Mozilla Corporation is wholly owned by the non-profit 501(c) Mozilla Foundation
- Mozilla designs, builds and distributes open-source software with thousands of volunteer contributors and collaborators
What they value
- Open and free is better than closed and controlled
- Diversity, equity, inclusion, and belonging