Senior Software Engineer, Add-Ons

Mozilla

. Deliver major features and architectural improvements across the Add-ons stack, including automated moderation pipelines, Reviewer tools, and DevHub.

Posted 9/15/2026full-timeRemote • BelgiumSenior💰 €56,000 - €74,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates strong expertise in building and maintaining production applications using Python/Django, with a focus on CI/CD systems and observability practices. Capable of improving engineering standards and fostering collaboration within distributed teams.

Highest-signal resume keywords

Python/Django DevelopmentCI/CD Pipeline ManagementObservability PracticesTechnical WritingCollaboration in Distributed Teams

ATS Keywords

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Hard Skills

Production Application DevelopmentAutomated Testing WorkflowsInfrastructure as CodeDebugging Complex IssuesCode Review StandardsIncident ResponseAsynchronous ProcessingMetrics and LoggingService-Level ObjectivesDesign Documentation

Soft Skills

CollaborationCommunicationMentoringKnowledge SharingFeedback Provision

Tools & Technologies

Google CloudKubernetesMySQLReactTypeScript

Industry Keywords

Production ReadinessTrust and SafetyAutomated ModerationChaos EngineeringDisaster Recovery Testing

Tech Stack

Tools & technologies

CloudDjangoKubernetesMySQLPythonReactTypeScript

About the role

Key responsibilities & impact

Deliver major features and architectural improvements across the Add-ons stack, including automated moderation pipelines, Reviewer tools, and DevHub.
Establish and maintain engineering standards for 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 systems enabling safe development, deployment, observation, and operation of production services.
Improve CI/CD pipelines using declarative, pipeline-as-code approaches.
Deliver work iteratively using visible backlogs, short feedback cycles, retrospectives, and stakeholder demonstrations.
Write technical documentation including design notes, Architecture Decision Records, runbooks, and incident write-ups.
Trace requests and asynchronous jobs through unfamiliar codebases to understand failures and identify improvements.
Collaborate with designers, product managers, QA, and community contributors.
Contribute through pull requests, code reviews, and discussions.
Develop submission flows, trust and safety signals, and modernized DevHub and Reviewer tools.
Work across Python/Django, MySQL, React/TypeScript, and asynchronous processing systems.
Create internal developer platforms and paved paths for safe, consistent software delivery.
Contribute to team ceremonies and process improvement.
Support deployments, monitoring, and incident response.

Requirements

What you’ll need

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, including metrics, logging, tracing, service-level objectives, and 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 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, including design documents, ADRs, runbooks, and incident reports.
Experience working iteratively with a visible backlog, regular 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.
Commitment to Mozilla values: welcoming differences, being relationship-minded, practicing responsible participation, and having grit.
Bonus: Google Cloud, Kubernetes, infrastructure-as-code, policy-as-code, SLOs, error-budget reliability practices, chaos engineering, disaster recovery testing, production readiness reviews, trust and safety, automated moderation, abuse prevention, and open-source contributions.

Benefits

Comp & perks

Generous performance-based bonus plans to all eligible employees - we share in our success as one team
Rich medical, dental, and vision coverage
Generous retirement contributions with 100% immediate vesting (regardless of whether you contribute)
Quarterly all-company wellness days where everyone takes a pause together
Country specific holidays plus a day off for your birthday
One-time home office stipend
Annual professional development budget
Quarterly well-being stipend
Considerable paid parental leave
Employee referral bonus program
Other benefits (life/AD&D, disability, EAP, etc. - varies by country)