Teams at Mozilla

Develop and optimize Firefox performance across Windows, Android, Linux, and macOS. Write code, tests, prototypes, and tooling; profile and diagnose bottlenecks; improve benchmarks; and lead performance initiatives. Collaborate across engineering teams, educate developers, drive projects to completion, own browser performance areas, and contribute to the team’s technical roadmap.

Design and implement experiments deep within browser engine subsystems, including DOM, layout, rendering, accessibility, JavaScript runtimes, and networking. Investigate browser behavior, prototype capabilities for programmatic web interaction, measure performance and correctness, profile overhead, and document results. The role requires hands-on systems engineering, browser platform expertise, large-codebase development, and collaboration on AI-agent tooling.

Investigate and modify browser engine subsystems through hands-on experimentation, prototyping, instrumentation, profiling, and performance analysis. Build capabilities supporting reliable programmatic web interaction while evaluating correctness, compatibility, and efficiency. The role requires deep browser internals expertise, strong C++ or Rust proficiency, systems debugging experience, and understanding of web platform behavior. Engineers will collaborate with technical leadership, use AI-assisted development tools, and document reproducible results, including unsuccessful experiments.