Staff Software Engineer, Browser – New Products

Mozilla

. Design and implement experiments within browser engine subsystems .

Posted 11/10/2026full-timeRemote • CanadaLead💰 CA$130,000 - CA$170,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates deep expertise in browser engine subsystems, particularly in performance debugging, memory ownership, and concurrency. Proficient in C++ or Rust, with a strong understanding of web platform behavior and the ability to build and evaluate JavaScript tools.

Highest-signal resume keywords

C++ ProficiencyRust ProficiencyBrowser Engine Subsystem ExpertisePerformance DebuggingJavaScript Tool Development

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Performance MeasurementMemory OwnershipConcurrencyObject LifetimesProfilingTracingRegression TestingConformance TestingPrototype DevelopmentWeb Platform Behavior

Soft Skills

Curiosity About AI AgentsInvestigative SkillsTeam Collaboration

Tools & Technologies

AI ToolsDebugging ToolsScripting Tools

Industry Keywords

DOMWeb APIsLayout and RenderingAccessibilityJavaScript RuntimesNetworkingProcess ArchitectureGeckoServoBlink

Tech Stack

Tools & technologies

JavaScriptRustC++

About the role

Key responsibilities & impact

Design and implement experiments within browser engine subsystems
Investigate how internal data structures and execution behavior affect performance, correctness, and developer-tool interfaces
Evaluate ways to represent and expose browser state efficiently and accurately
Identify tradeoffs including information loss, implementation complexity, and compatibility with dynamic web content
Prototype engine capabilities supporting 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 each change’s effect, and document unsuccessful and successful experiments
Verify that gains hold beyond prototype-development workloads
Profile overhead introduced by new capabilities and pursue measurement-supported improvements
Use AI tools to accelerate coding and analysis, verifying output through debugging, tests, and measurement
Work closely with the team’s technical lead as a hands-on individual contributor

Requirements

What you’ll need

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
Strong proficiency in C++ or Rust
Experience navigating a large systems codebase
Practical knowledge of memory ownership, concurrency, object lifetimes, and performance debugging
Ability to build 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
Strong understanding of web platform behavior and compatibility
Experience with profiling, tracing, regression tests, or conformance tests
Curiosity about AI agents and willingness to work directly with agent harnesses and coding tools
Contributions to Gecko, Servo, Blink, WebKit, or another browser engine (nice to have)
Experience maintaining an open-source project (nice to have)
Technical leadership in a small team building a new product (nice to have)
Experience with accessibility infrastructure, browser security, profiling, or automated evaluation of agent workflows (nice to have)

Benefits

Comp & perks

Generous performance-based bonus plans to all eligible employees - we share in our success as one team
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)