Senior Software Engineer, -Ons

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 Dev Hub 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.

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.

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 Dev Hub 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.

• Deliver major features and architectural improvements across the Add-ons stack, including automated moderation pipelines, Reviewer tools, and Dev Hub.
• 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.
• Write clear technical documentation, including design notes, Architecture Decision Records, runbooks, and incident write‑ups.
• Work effectively in…