Senior Software Development Engineer (Performance)
at Mozilla Corporation
Core Product-Firefox
Remote US, Remote Canada, Toronto Office, Berlin Office

The Company

A lot of companies say they’re “mission-driven”. 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

At Mozilla, we believe that the web should be responsive, pages should load quickly, and resources should be used thoughtfully. The performance program is dedicated to building performance for every experience, growing a culture of performance, and to bring a balance between what is good for the users of the web and what is good for the builders of the web.

As a software engineer in performance you will be helping to redefine experimental, manual, and error-prone processes for gathering key performance metrics into robust automated solutions. You will work closely with performance specialists to identify the most valuable measurements and the most suitable environments in which to evaluate them. In this position you will collaborate with the entire team in the design of automation solutions, and contribute to an inclusive mentoring environment for junior team members.

What You'll Get To Do

  • Design, develop and maintain performance test frameworks.
  • Optimize our regression detection algorithms for speed and accuracy.
  • Automate our regression response process.
  • Help to identify gaps in test coverage.
  • Develop new performance tests.
  • Enable and adjust testing schedules for performance tests in CI.
  • Contribute to team planning sessions.
  • Attend regular triage sessions for bugs related to performance test automation.
  • Maintain documentation for performance test automation frameworks and tests.
  • Execute local tests and report results as needed.
  • Provide support for the performance test infrastructure.

What You Bring

Minimum Qualifications

  • 3+ years recent software development or programming experience.
  • Experience building and maintaining automated test frameworks (test harnesses).
  • Familiar with low-level aspects of performance, debugging, and profiling.
  • Intermediate experience with Python.
  • Familiarity with JavaScript.
  • Good understanding of web technologies.
  • Good communication skills.

Bonus points for

  • Experience measuring system resources such as CPU, processes, and memory.
  • Understanding of the mobile ecosystem.
  • Experience working with distributed teams.


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 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 essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at to request an 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


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
  • 9 global offices: Mountain View, San Francisco, Portland, Vancouver, Toronto, Paris, London, 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