Senior Software Engineer, APZ (Asynchronous Pan & Zoom)

Mozilla; Toronto; On-site; CAD 104,000 - 139,000; Full time

Benefits offered by this job

Generous bonus plans

Comprehensive health coverage

Retirement contributions with vesting

Home office stipend

Professional development budget

Job summary

Mozilla is seeking a Frontend/Engine engineer to contribute to Firefox rendering, layout, and APZ features across Android, Windows, Linux, and macOS.

You will work on high‑quality C/C++ and Rust code, participate in open source collaboration, and help optimize rendering performance while operating in a distributed, remote‑first environment.

Qualifications

• Bachelor's degree in Computer Science or equivalent.
• Experience developing C/C++ and/or Rust applications.
• Strong debugging and optimization skills in a multi‑threaded environment.
• Experience with memory and performance optimization tools.
• Open source contributions or browser development experience is a plus.

Responsibilities

• Collaborate with Mozillians to identify and fix issues and seek help when needed.
• Write high-quality, performant, open source code that complies with standards.
• Develop layout, graphics, and interaction techniques to optimize Firefox rendering.
• Participate in code reviews, planning, and team discussions.
• Triage and test bugs, drilling down to root causes and exploring solutions.

Skills

C/C++

Rust

Open source

Multi-threading

Debugging

Education

Bachelor's degree in Computer Science

Job description

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

The Firefox Platform Layout/APZ team is a global community of engineers who care deeply about how the Web looks and feels. We are the team responsible for Pan, Scrolling, Zoom, Page Layout, CSS, images, text, printing, and animations in Gecko, the engine behind Firefox. You will be able to design and develop standards‑compliant CSS and page layout features that all of our users see, with a current particular focus on Asynchronous Pan and Zoom (APZ), our technology for making user interaction snappy and delightful. Our team is geographically‑distributed, and working virtually and in the open is the norm. You can expect to work on the code driving the Firefox browser on a number of platforms - Android, Windows, Linux, and macOS. Our focus is on writing fast, lightweight and maintainable code to make Firefox phenomenal for users.

What You’ll Do

• Work cooperatively with other Mozillians to identify and correct issues, and ask for help as needed
• Write high-quality, performant, open source, and standards compliant code
• Develop innovative layout, graphics, and user interaction techniques, algorithms and tools to maximize the rendering quality and performance of Firefox
• Participate in regular code reviews, team meetings and long‑term planning
• Help triage and test bugs, taking the initiative to drill down to root causes and explore potential solutions

What You’ll Bring

• Bachelor’s degree or equivalent experience in Computer Science or similar field
• Experience developing C/C++ and/or Rust applications
• Strong debugging and optimization skills in a multi‑threaded environment
• Experience with memory and performance optimization tools
• Proven record of finishing projects where the work spans several months
• Experience participating in and contributing to open source projects and/or web browser development would be beneficial.
• Excellent written and verbal communication skills
• Ability to quickly learn and be effective with a large code base

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 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 [e-mail] 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

Req ID: R3181

Hiring Ranges

• Canada Tier 1 Locations: $104,000—$139,000 CAD
• Canada Tier 2 Locations: $95,000—$126,000 CAD