Staff Software Engineer, Browser – New Products

Mozilla

. Design and implement experiments within browser engine subsystems .

Posted 11/10/2026full-timeRemote • United StatesLead💰 $138,000 - $217,000 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 web platform behavior. Proficient in C++ or Rust, with a strong ability to prototype and evaluate engine capabilities while contributing to open-source projects.

Highest-signal resume keywords

C++ ProficiencyRust ProficiencyBrowser Engine Subsystem ExpertisePerformance DebuggingWeb Platform Behavior Understanding

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

C++RustPerformance DebuggingMemory OwnershipConcurrencyObject LifetimesJavaScript Tool DevelopmentProfilingTracingRegression Testing

Soft Skills

CuriosityProblem-SolvingTechnical Leadership

Tools & Technologies

AI ToolsDebugging ToolsScripting Tools

Industry Keywords

Browser EngineDOMWeb APIsLayout and RenderingAccessibilityJavaScript RuntimesNetworking ArchitectureOpen-Source Project MaintenanceGeckoServo

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 approaches for representing and exposing browser state efficiently and accurately
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 effects, and document unsuccessful and successful experiments
Validate that gains extend beyond prototype-development workloads
Profile overhead introduced by new capabilities and pursue measurement-justified improvements
Use AI tools to accelerate coding and analysis, verifying output through debugging, tests, and measurement
Work as a hands-on individual contributor owning engine-level investigations and implementation with the technical lead

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
Ability to investigate unfamiliar code, form precise hypotheses, construct useful prototypes, and interpret results
Strong understanding of web platform behavior and compatibility, including document structure, script execution, rendering, and user interaction
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)