Join the Firefox Desktop Integrations team to build and maintain OS-level features that increase engagement (notifications, pinning, launch on login, default browser flows). The role involves implementing experiments with feature flags and telemetry, working on platform-specific integration challenges (Windows/macOS), collaborating with product/design/data teams, and contributing to an open-source codebase.

Work on designing, implementing, testing, and shipping security and hardening features for Firefox, improving security architecture (cryptographic protocols, WebPKI, privilege isolation), and diagnosing stability, performance, and memory issues in a complex multithreaded, cross-platform codebase. Requires 3+ years in low-level systems programming with strong C/C++ proficiency, debugging skills, familiarity with web technologies, and interest or experience in Rust.

Work on Firefox Security to design, implement, test, and ship security features (including privilege isolation, cryptographic protocols, and WebPKI), diagnose multithreaded stability/performance issues, and collaborate across teams. Requires 3+ years in low-level systems programming with strong C/C++ proficiency and familiarity with web technologies and Rust. Role listed as Remote Sweden.

Work on designing, implementing, testing, and shipping security and hardening features for Firefox across multiple operating systems. Improve core security mechanisms (cryptographic protocols, WebPKI, security-sensitive web APIs), investigate and fix security issues, and diagnose stability, performance, and memory problems in a large multi-language codebase. Requires 3+ years in low-level systems programming with strong C/C++ skills and familiarity or interest in Rust.

Design, implement, test, and ship security and hardening features for enterprise Firefox users; improve core security architecture (cryptographic protocols, WebPKI, security-sensitive web APIs) and build privilege isolation. Diagnose and resolve stability, correctness, performance, and memory issues in a complex, multithreaded, cross-platform native codebase. Requires 3+ years of low-level systems programming experience with strong proficiency in C and/or C++ and familiarity with Rust and web technologies.

Work on designing, implementing, testing, and shipping security and hardening features for Firefox across multiple operating systems. Improve core security mechanisms (cryptographic protocols, WebPKI, security-sensitive web APIs), investigate and fix security issues, and diagnose stability, performance, and memory problems in a large, multithreaded codebase. Requires 3+ years in low-level systems programming with strong C/C++ proficiency and security fundamentals; familiarity with web technologies and Rust is desirable.

Join Firefox Security to build and improve security architecture across platforms (privilege isolation, cryptographic protocols, WebPKI, security-sensitive APIs). Responsibilities include designing, implementing, testing, and shipping security features; investigating security issues and fixing stability, performance, and memory problems in a multithreaded, cross-platform codebase. Requires 3+ years low-level/software systems experience, strong C/C++ proficiency, familiarity or interest in Rust and web technologies, and experience working with distributed teams. Salary range listed for Remote UK: £66,000–£87,000.

Work on designing, implementing, testing, and shipping security and hardening features for Firefox, improving security architecture (including cryptographic protocols and WebPKI), investigating and fixing security issues, and diagnosing stability, correctness, performance, and memory problems in a large, multithreaded, cross-platform codebase. Requires 3+ years of low-level systems programming experience, strong C/C++ proficiency, security knowledge, and familiarity with web technologies and Rust.

Work on Firefox Security to design, implement, test, and ship security features (privilege isolation, cryptography, WebPKI, security-sensitive web APIs), investigate and fix security issues, and improve reliability and performance in a complex, multithreaded, cross-platform codebase. Requires 3+ years in low-level systems programming with proficiency in C and/or C++ and familiarity or interest in Rust.

Join the geographically distributed Firefox Performance team to identify and fix browser performance bottlenecks, write code and tests, build prototypes, drive cross-team performance work, contribute to benchmarks and tooling, and own performance for significant areas of the browser. Requires 5+ years relevant experience, deep C++ proficiency, working JavaScript skills, and experience with profiling tools (e.g., VTune, Xperf).

Mozilla seeks an experienced browser engine engineer to investigate browser behavior, prototype engine-level changes, instrument and measure performance and correctness, and work closely with a small cross-disciplinary team. Requires substantial experience with browser internals (e.g., DOM, layout, rendering, JS runtimes), strong C++ or Rust skills, profiling and testing practices, and the ability to build scripting/tools and prototypes. Hiring ranges for Canada are provided in the posting.

Mozilla seeks a senior staff-level browser engineer to design and implement experiments in browser engine subsystems (DOM, layout, rendering, JS runtimes, accessibility, etc.), prototype engine capabilities, instrument and measure performance and correctness, and work closely with a small technical team. Strong systems expertise in C++ or Rust, profiling, concurrency, and working in large codebases is required; experience with AI tools and open-source browser projects is a plus.

The Staff Software Engineer, Web Application Services will lead technical architecture and development for new web-based products (calendar, secure file storage/transfer) extending Thunderbird. Responsibilities include design and implementation, establishing software patterns, building analytics/infrastructure, mentoring engineers, and collaborating across distributed teams and community contributors. The role is full-time, fully remote, requires 10+ years of experience, strong JavaScript skills and proficiency in at least one other language (e.g., Python, Rust, Go, C++), and periodic international travel.

Lead technical architecture and implementation for web-based Services (e.g., calendar, secure file storage). Contribute code, prototypes, infrastructure and analytics; make technology decisions; mentor other engineers; collaborate with cross-functional and community contributors. Requires 10+ years web development experience and expert JavaScript plus experience in at least one of Python, Rust, Go, or C++.

Lead the technical architecture and development of Thunderbird Web Services (examples: calendar, secure file storage). Responsibilities include writing code and prototypes, establishing software patterns, building analytics and infrastructure, mentoring engineers, and collaborating remotely across product, design, QA, and community contributors. Full-time, fully remote role for applicants residing in and authorized to work in Canada; no visa sponsorship provided. Periodic international travel may be required.

Mozilla is hiring a Staff Application Engineer (Salesforce) to lead architecture, implementation, and ongoing ownership of a Sales Cloud platform for enterprise product lines. Responsibilities include designing scalable data and security models, building declarative and code-based solutions (Flow, Apex, LWC), integrating with systems such as NetSuite and BigQuery, establishing environment and release practices, and delivering AI/MCP integrations. The role is a hands-on senior individual contributor position requiring at least eight years of Salesforce engineering/architecture experience.

Mozilla is hiring a Senior Software Engineer to design, build, deploy, and operate backend services for Ecosystem Services. The role emphasizes end-to-end ownership, collaboration with frontend, CloudEng and product teams, on-call production support, observability (OpenTelemetry, Sentry, Prometheus, Grafana), and hands-on GCP and Docker-based deployment experience. Required: 4+ years backend development experience with Python, TypeScript/Node.js, or Rust and familiarity with PostgreSQL and SQL optimization.

Mozilla is hiring Senior Software Engineers for multiple Ecosystem Services backend teams to design, build, deploy, and operate backend platforms focused on privacy, security, and reliability. The role requires end-to-end ownership of services, collaboration with cross-functional teams, on-call rotation, and hands-on experience with backend languages (Python/TypeScript/Node.js or Rust), PostgreSQL, Docker, and GCP-based deployments and observability tooling.

Join Mozilla's Ecosystem Services Team to build, operate, and maintain back-end platforms used by Firefox and other Mozilla products. Responsibilities include backend development, cloud deployments and operations (GCP/Docker), observability and monitoring (OpenTelemetry, Sentry, Prometheus, Grafana), participating in on-call rotations, API design, and collaborating with frontend, CloudEng, product, and UX teams. Requires 4+ years of software development experience with strong backend focus and professional experience in Python, TypeScript/Node.js, or Rust, plus PostgreSQL and hands-on GCP/DevOps experience.

Work on the WebCompat team's internal tooling by building and improving dashboards (triage, reporting, metrics) and improving the broken-site-report screenshot capture and pipeline. Collaborate with the WebCompat team (including QA) to convert reporting and triage needs into reliable tooling. Required skills include web development (JavaScript, HTML, CSS), Python and Django, dashboard/data view experience, and comfort with tooling, automation, and web services. Familiarity with Bugzilla, screenshot/automation pipelines, and machine learning are listed as preferred.