Senior Software Engineer, Add-Ons
Senior engineer on Mozilla's Add-ons team building addons.mozilla.org and the Firefox extension ecosystem — automated moderation pipelines, Reviewer tools, and DevHub. Day-to-day spans Python/Django backends, React/TypeScript frontends, MySQL, CI/CD, observability, and production reliability across a distributed, open-source team.
- Compensation
- CA$94K–CA$139K / yr
- Location
- Remote Canada
- Work setup
- Remote
- Seniority
- Senior
- Employment
- Not specified
- Experience
- 25+ years
- Category
- Software engineering
- Posted
Skills
Must have
- Strong hands-on experience building and maintaining production applications with Python/Django
- Experience operating and improving production software systems where reliability and safe delivery matter
- Strong experience with CI/CD systems and treating pipelines and infrastructure declaratively as code
- Experience designing or improving automated testing and deployment workflows, including integration testing and staged or progressive delivery
- Strong understanding of observability: metrics, logging, tracing, service-level objectives, actionable alerting
- Experience building or maintaining internal tools or platforms used by other engineering teams
- Experience defining or improving engineering practices such as code review standards, operational readiness, runbooks, incident response, on-call expectations, or definitions of done
- Ability to read and understand unfamiliar codebases and trace application behavior across frontend, backend, asynchronous jobs, data stores, and infrastructure
- Experience debugging complex production issues and turning learnings into lasting system improvements
- Strong technical writing skills: design documents, ADRs, runbooks, incident reports
- Experience working iteratively with a visible backlog, stakeholder feedback, and retrospectives
- Strong collaboration and communication skills in a distributed team environment
- Willingness to share knowledge and mentor peers in operational and reliability practices
Nice to have
- Experience with Google Cloud and operating Kubernetes
- Experience with infrastructure-as-code and policy-as-code tooling
- Experience establishing SLOs and error-budget-based reliability practices
- Experience with chaos engineering, disaster recovery testing, or production readiness reviews
- Experience with trust and safety, automated moderation, abuse prevention, or other adversarial systems
- Contributions to open source projects
Full description
Why Mozilla?
Mozilla Corporation is the non-profit-backed technology company that has shaped the internet for the better over the last 25 years. We make pioneering brands like Firefox, the privacy-minded web browser. Now, with more than 225 million people around the world using our products each month, we’re shaping the next 25 years of technology and helping to reclaim an internet built for people, not companies. Our work focuses on diverse areas including AI, social media, security and more. And we’re doing this while never losing our focus on our core mission – to make the internet better for people.
The Mozilla Corporation is wholly owned by the non-profit 501(c) Mozilla Foundation. This means we aren’t beholden to any shareholders — only to our mission. Along with thousands of volunteer contributors and collaborators all over the world, Mozillians design, build and distribute open-source software that enables people to enjoy the internet on their terms.
About this team and role:
addons.mozilla.org (AMO) is the foundation of the Firefox add-ons ecosystem. It’s a showcase for developers to publish and grow their extensions, and a place of discovery for millions of users who customize Firefox to make it their own. Behind the scenes are the DevHub which enables developers to manage their extensions. To manage the ecosystem there are a series of Reviewer tools and automated moderation systems.
As a Senior Software Engineer, you’ll bring a passion for crafting resilient systems that accelerate our review and moderation teams to provide a first-class experience for Add-on developers. You’ll work closely with engineers, reviewers, developer support, and Add-ons leadership to turn ideas into polished features, modernize the platform and its architecture, and see your work reach millions of people around the world.
What you’ll do:
- 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.
- Provide peer feedback, share knowledge and help others grow.
- Build and improve the systems that enable Add-ons engineering to safely develop, deploy, observe, and operate production services.
- Improve our CI/CD pipelines using declarative, pipeline-as-code approaches that make changes reproducible, testable, and easy to review.
- Deliver work iteratively using a visible backlog, short feedback cycles, retrospectives, and demonstrations to stakeholders.