Senior Software Engineer, Security
at Mozilla Corporation
Core Product-Firefox
Remote France, Remote Canada, Remote Germany, Remote US, Remote UK
The Company

Our unique corporate structure guarantees that every decision we make upholds our mission: to make sure the internet stays available, safe, and welcoming to everyone. Beholden to neither shareholders nor investors, Mozilla Corporation is wholly owned by the not-for-profit Mozilla Foundation.

Along with 20,000+ volunteer contributors and collaborators all over the world, Mozilla Corporation’s staff designs, builds, and distributes software that allows people to enjoy the internet on their own terms. Our flagship product — the Firefox browser — has expanded into a family of products that protects users and alerts them of risks.

The Opportunity

  • The Senior Software Engineer is responsible for the planning, architecture, and delivery of major full stack software security projects within (“AMO”).
  • We’re looking for a passionate and creative individual to join a distributed team of talented and diverse engineers working to maintain, secure and grow our add-ons ecosystem.

What You'll Get To Do

  • Contribute to and demonstrate ownership over major components of the Firefox add-ons ecosystem with a focus on security, taking responsibility for their maintenance and improvement over time
  • Play a key role in improving our software architecture with the goal of increasing quality and maintainability over time
  • You will collaborate with people across Product, UX, Design, Engineering, QA, Localization, Ops, and Support teams to build and maintain core features
  • Step up to resolve product issues that impact our users – large and small
  • Write unit tests, automated regression tests, and track defects as they occur. Build performant, decoupled, testable, and maintainable code

What You Bring

Minimum Qualifications

  • 4+ years of software engineering experience using Python and JavaScript
  • Excellent communication skills. You can validate your decisions and communicate them clearly
  • Good knowledge of security analysis and threat modeling
  • Comfortable exploring solutions to complex problems and working collaboratively to pave the way forward in new problem spaces
  • Passionate about security and privacy
  • Bachelor's degree in computer science, engineering, mathematics, or a related program; or equivalent work experience

Bonus points for

We value a variety of voices. You don’t need to check every box on this list to apply.

  • Experience collaborating with geographically distributed team members
  • Experience with front-end web application development (CSS, HTML, DOM and related)
  • Experience with spam prevention or malware detection
  • The ability to mentor and inspire junior developers
  • Previous experience working in open source

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.

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 orientations, 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 crucial job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at 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. See our community participation guidelines for more information.

Group: D


Req ID: R1870

Applicant Privacy Notice

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

  • 700+ paid staff from over 30 countries
  • Thousands of volunteer contributors across six continents
  • 5 global offices: San Francisco, Toronto, Paris, Berlin, and Beijing
  • Hundreds of home offices globally

Our benefits are world-class

  • Flexible work environment (nearly half 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