Platform Security Engineer – Open-Source & Moderation

Mozilla; Greater London; On-site; GBP 90,000 - 130,000; Full time

Benefits offered by this job

Health insurance

Mental health support

Paid time off

Parental leave

401(k) plan

Professional development budget

Wellbeing stipend

Internet reimbursement for remote work

Job summary

A Senior Software Engineer - Operations at Mozilla in London will help build resilient systems for the Add-ons review and operations team, accelerating delivery to millions of users.

You will own full stack features (React/TypeScript frontends, Django backend, MySQL datastore), strengthen platform reliability, observability, and security, and contribute through open collaboration with Mozilla staff and the community.

Qualifications

• Strong experience with Python/Django or similar backend frameworks.
• Strong collaboration and communication skills in a distributed team environment.
• Adept at navigating ambiguity, exploring solutions, and shaping direction in new problem spaces.
• Being relationship-minded.
• Understanding of web security principles and practices.
• Practicing responsible participation.
• Experience building modern web applications.
• Having grit.
• Commitment to our values: Welcoming differences.
• Experience in building automated security systems.
• Exposure to cloud infrastructure (Google Cloud or similar).
• Contributions to open source projects.
• Experience with policy-compliant ecosystem moderation tools.

Responsibilities

• Deliver major features and architectural improvements across the Add-ons stack, including automated moderation pipelines, Reviewer tools, and DevHub
• Create robust observability systems and data-backed insights
• Provide peer feedback, share knowledge and help others grow
• Improve platform reliability through deployments, monitoring, and incident response
• Help keep the platform safe and trustworthy, with attention to security and user trust
• Step in to resolve issues impacting users and developers, from small bugs to larger incidents
• Collaborate with designers, product managers, QA, and community contributors to deliver end-to-end improvements
• Contribute in the open through pull requests, code reviews, and discussions
• Work on: Full stack development: React/TypeScript frontends, Django backend, MySQL datastore; Platform reliability: deployments, monitoring, and incident response on Google Cloud; Feature development: submission flows, trust and safety signals, DevHub and Reviewer tools modernization; Ecosystem moderation: abuse report management, policy compliance, and ecosystem safety; Open collaboration: We work in the open, with contributions from Mozilla staff and community members

Skills

Python/Django backend

Distributed collaboration

Ambiguity navigation

Relationship-minded

Web security awareness

Tools

Google Cloud

Open source contributions

Job description

A Senior Software Engineer - Operations at Mozilla in London will help build resilient systems for the Add-ons review and operations team, accelerating delivery to millions of users.

You will own full stack features (React/TypeScript frontends, Django backend, MySQL datastore), strengthen platform reliability, observability, and security, and contribute through open collaboration with Mozilla staff and the community.