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Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md). --- # Senior Software Engineer, Add-Ons - **Company:** Mozilla Corporation - **Location:** Madrid, Spain (Remote available) - **Contract:** Permanent contract - **Skills:** Automation of Tests, Code Review, Continuous Integration, Data Stores, Software Debugging, Django Web Framework, Firefox, Data Intelligence, Python (Programming Language), MySQL, Open Source Technology, Runbook, TypeScript, Data Logging, ReactJS, Backend, Data Analytics, Build Tools, Front End Software Development - **Published:** September 29, 2026 - **Apply:** https://www.buscojobs.com.es/senior-software-engineer-add-ons-en-madrid-ID-373216134 ## About the Role Proven reliability-focused production software operations Strong CI/CD experience and declarative infrastructure Experience designing automated tests and progressive delivery Strong observability knowledge (metrics, logging, tracing, SLOs, alerting) Experience building internal tools/platforms used by engineers Defining/improving engineering practices (code review, runbooks, incident response) Ability to read unfamiliar codebases and trace end-to-end behavior Proven debugging of complex production issues and turning learnings into improvements Strong technical writing (design docs, ADRs, runbooks, incident reports) Experience working with a visible backlog and stakeholder feedback Strong collaboration and communication in distributed teams Willingness to mentor peers on reliability practices Commitment to Mozilla values: welcoming differences, relationship-minded, responsible participation, grit collaboration communication mentorship Python/Django MySQL React/TypeScript ## Description OverviewAs a Senior Software Engineer on the AMO/DevHub domain, you will help shape the Firefox add-ons ecosystem by delivering major features and architectural improvements.You'll partner with engineers, reviewers, product leads, and the community to modernize the platform, improve reliability, and scale review and moderation.You'll build observable, data-driven systems and guide the team with strong engineering practices.This role offers impact at scale and a chance to contribute to an open, privacy-respecting internet.Compensaciones / Beneficiosgenerous performance-based bonusmedical, dental, and vision coverageretirement contributions with immediate vestingwell-being stipend and wellness dayshome office stipendprofessional development budgetResponsabilidadesDeliver major features and architectural improvements across the Add-ons stack (automated moderation pipelines, Reviewer tools, DevHub)Establish and maintain engineering standards (code review, production readiness, incident response, runbooks, IaC)Create robust observability systems and data-backed insightsMentor peers and share knowledge to grow the teamImprove CI/CD pipelines with declarative, pipeline-as-code approachesDeliver work iteratively with clear backlog and stakeholder reviewsProduce technical documentation (design notes, ADRs, runbooks, incident reports)Trace and diagnose failures across frontend, backend, asynchronous jobs, data stores, and infraCollaborate with designers, PMs, QA, and community contributors to ship end-to-end improvementsContribute to open source via PRs, code reviews, and discussionsWork on: feature development (submission flows, trust signals, DevHub/Reviewer tools modernization)AMO stack: Python/Django, MySQL, React/TypeScript, asynchronous processingInternal developer platforms: build tools to help teams ship and operate safelyRequisitos principalesHands-on production-grade Python/Django experienceProven reliability-focused production software operationsStrong CI/CD experience and declarative infrastructureExperience designing automated tests and progressive deliveryStrong observability knowledge (metrics, logging, tracing, SLOs, alerting)Experience building internal tools/platforms used by engineersDefining/improving engineering practices (code review, runbooks, incident response)Ability to read unfamiliar codebases and trace end-to-end behaviorProven debugging of complex production issues and turning learnings into improvementsStrong technical writing (design docs, ADRs, runbooks, incident reports)Experience working with a visible backlog and stakeholder feedbackStrong collaboration and communication in distributed teamsWillingness to mentor peers on reliability practicesCommitment to Mozilla values: welcoming differences, relationship-minded, responsible participation, gritcollaborationcommunicationmentorshipPython/DjangoMySQLReact/TypeScript ## Related Videos - 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