Staff Site Reliability Engineer (Tools & Systems)

Join Mozilla as a Staff Site Reliability Engineer (Tools & Systems) and work on the tools and systems that support Firefox engineering. This broad software engineering role involves internal engineering systems, developer tooling, workflow automation, and the infrastructure required to operate them. You will contribute to the software, tools, and systems that support Firefox engineering, and work across projects and technical domains. Open source is fundamental to how we work, and contributing back to the broader open-source ecosystem is an important part of the role.

• Design, build, deploy, and operate software and systems supporting Firefox engineering, including developer tooling, CI/CD, workflow automation, and AI-assisted development tools.
• Own complex technical problems end-to-end across software, cloud, and operational layers, improving reliability, performance, observability, and cost efficiency.
• Work with Firefox engineering, Cloud Engineering, IT, and other teams to solve problems that span technical and organizational boundaries, using telemetry, metrics, and data analysis to guide engineering decisions.

• You communicate openly, consistently, and respectfully, and enjoy teaching and helping others build skills in unfamiliar technical areas
• Experience across several areas such as CI/CD, containers and orchestration, networking, databases, observability, or developer tooling
• Experience using data, telemetry, and metrics to investigate technical problems and make decisions
• Experience building and deploying and operating production systems in cloud environments, including utilizing infrastructure as code such as Terraform
• You are comfortable jumping into unfamiliar systems and getting them into a sustainable state
• Strong software engineering skills and substantial hands-on experience deploying and operating production systems are core requirements for this role. We do not expect you to be an expert in every technology or domain listed below
• You enjoy moving across projects and technical domains, taking ownership of problems and looking for patterns that make the next one easier to solve
• Strong programming skills in languages such as Python or JavaScript/TypeScript. Experience with C++ or Rust is useful
• Familiarity with modern AI-assisted development tools and an understanding of their capabilities, limitations, and appropriate use
• You work effectively across disciplines and can translate between software, infrastructure, and operational concerns
• You combine hands-on engineering with systems thinking and longer-term technical judgment