Senior Security Engineer, Add-ons Operations

at Mozilla Corporation

Team:Firefox Locations:Remote Canada, Remote Germany, Remote France, Remote UK

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 - Operations, you’ll bring a passion for crafting resilient systems that accelerate our review and operations team to provide a first-class experience for Add-on developers. You’ll work closely with engineers, reviewers, developer relations, 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.
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.

What you’ll bring:

Experience building modern web applications.
Strong experience with Python/Django or similar backend frameworks.
Understanding of web security principles and practices.
Strong collaboration and communication skills in a distributed team environment.
Adept at navigating ambiguity, exploring solutions, and shaping direction in new problem spaces.
Commitment to our values:
Welcoming differences
Being relationship-minded
Practicing responsible participation
Having grit

Bonus points for:

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.

What you’ll get:

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)

About Mozilla

Mozilla exists to build the Internet as a public resource accessible to all because we believe that open and free is better than closed and controlled. When you work at Mozilla, you give yourself a chance to make a difference in the lives of Web users everywhere. And you give us a chance to make a difference in your life every single day. Join us to work on the Web as the platform and help create more opportunity and innovation for everyone online.

Commitment to diversity, equity, inclusion, and belonging

Mozilla understands that valuing diverse creative practices and forms of knowledge are crucial to and enrich the company’s core mission. We encourage applications from everyone, including members of all equity-seeking communities, such as (but certainly not limited to) women, racialized and Indigenous persons, persons with disabilities, persons of all sexual orientation s, gender identities, and expressions.

We will ensure that qualified individuals with disabilities are provided reasonable accommodations to participate in the job application or interview process, to perform essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at hiringaccommodation@mozilla.com to request accommodation.

We are an equal opportunity employer. We do not discriminate on the basis of race (including hairstyle and texture), religion (including religious grooming and dress practices), gender, gender identity, gender expression, color, national origin, pregnancy, ancestry, domestic partner status, disability, sexual orientation, age, genetic predisposition, medical condition, marital status, citizenship status, military or veteran status, or any other basis covered by applicable laws. Mozilla will not tolerate discrimination or harassment based on any of these characteristics or any other unlawful behavior, conduct, or purpose.

Group: D

#LI-REMOTE

Req ID: R3023

Hiring Ranges:

Remote UK

£65,000—£87,000 GBP

Why Mozilla?

At Mozilla, we’re serving humanity—by maintaining a safe, open internet—while also helping the individual humans employed here to reach their personal and professional goals. With a relatively small team serving hundreds of millions of people, a culture of exploration, and a commitment to mentorship, opportunities abound to learn and grow at Mozilla.

Our values drive our actions

Purpose is built into our work, with our mission driving every decision
We challenge assumptions, the status quo, ourselves, and each other
We are transparent: in our code, our business partnerships, and our everyday interactions
We seek out people from diverse backgrounds and with perspectives different from our own
We pair purpose with performance and put people ahead of profit

Our impact is global

1000+ paid staff from over 30 countries
Thousands of volunteer contributors across six continents
2 global offices: Berlin and Toronto
9 coworking space locations: San Francisco, San Mateo, London, Paris, Portland, Tulsa, Vancouver, Chicago, and Bellevue
Hundreds of home offices globally

Our benefits are world-class

Flexible work environment (majority of Mozillians work remotely)
Industry-leading paid parental leave (up to 26 weeks of fully paid leave for childbearing parents and up to 12 weeks for non-childbearing parents)
Reimbursement for professional development (up to $3,000/year)
A work setup including the latest hardware and software of your choice

Senior Security Engineer, Add-ons Operations