Senior Software Engineer (Add-Ons)

Join Mozilla as a Senior Software Engineer for Add-ons, where you'll play a key role in shaping the Firefox add-ons ecosystem. You'll work closely with various teams to deliver major features, improve engineering standards, and enhance platform reliability. Enjoy comprehensive health benefits, generous time off, parental leave, and a commitment to your professional development.

Contributions to open source projects

Responsibilities

• Deliver major features and architectural improvements across the Add-ons stack, including automated moderation pipelines, Reviewer tools, and DevHub.
• Help establish and maintain engineering standards across areas such as code review, definition of done, production readiness, runbooks, incident response, on-call practices, coding conventions, and infrastructure as code.
• Create robust observability systems and data-backed insights, and improve our CI/CD pipelines using declarative, pipeline-as-code approaches.

Commitment to our values

• Strong understanding of observability as an engineering discipline, including metrics, logging, tracing, service-level objectives, and actionable alerting
• Ability to read and understand unfamiliar codebases and trace application behavior across frontend, backend, asynchronous jobs, data stores, and infrastructure

Requirements

• Experience debugging complex production issues and turning what you learn into lasting system improvements
• Strong collaboration and communication skills in a distributed team environment
• Experience building or maintaining internal tools or platforms used by other engineering teams, with an understanding that internal systems have users, reliability expectations, roadmaps, and lifecycle considerations

Welcoming differences

• Experience operating and improving production software systems where reliability and safe delivery matter
• A willingness to share knowledge and mentor peers in operational and reliability practices

Having grit

• Experience defining or improving engineering practices such as code review standards, operational readiness, runbooks, incident response, on-call expectations, or definitions of done
• Strong hands-on experience building and maintaining production applications with Python/Django
• Strong experience with CI/CD systems and treating pipelines and infrastructure declaratively as code
• Experience working iteratively with a visible backlog, regular stakeholder feedback, and retrospectives that result in concrete improvements
• Being relationship-minded
• Strong technical writing skills, with experience creating useful documentation such as design documents, ADRs, runbooks, and incident reports
• Practicing responsible participation
• Experience with Google Cloud and operating Kubernetes

Experience with infrastructure-as-code tooling and policy-as-code

• Experience establishing SLOs and error-budget-based reliability practices
• Experience with chaos engineering, disaster recovery testing, or production readiness reviews

Preferred

• Experience designing or improving automated testing and deployment workflows, including integration testing and staged or progressive delivery
• Experience with trust and safety, automated moderation, abuse prevention, or other adversarial systems