Senior Software Engineer, Firefox Desktop

Mozilla · Remote Belgium · Remote

Posted 7/10/2026 · last confirmed live 8/26/2026

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: The Firefox team is a community of engineers who care deeply about delivering the fastest, friendliest, most usable browser possible. We are responsible for making the things you see in the browser work securely, quickly, and well! Desktop Integrations is a cross-functional team that focuses on updates, installs and integrating Firefox with different OS platforms. As part of the Desktop Integrations team, you will be responsible for all things related to OS integration (particularly Windows and macOS) and helping us grow our user base.  Our team is geographically distributed, and working in the open is the norm. We contribute to the code driving the Firefox browser on a number of desktop platforms. About the role:  A Senior Software Engineer contributes to architectural discussions, and driving feature development within a team. At Mozilla, Senior Engineers are expected to work independently on scoped projects, collaborate closely with peers, and play a key role in delivering high-quality software that aligns with team goals. What you’ll do: Contribute to the development and improvement of Firefox features related to installs, updates, and OS integrations. Help implement enhancements to the Firefox installation and update experience, using data insights to guide development. Tackle platform-specific challenges in low-level operating system integration on Windows and/or macOS. Collaborate with your manager and teammates to scope and prioritize work in alignment with the team’s goals. Participate in code reviews and contribute to technical discussions with peers. Take ownership of complex bugs and lead efforts to improve the Firefox experience for hundreds of millions of users. Work closely with your geographically distributed team in a highly collaborative environment. What you’ll bring:  3-5 years experience as Software Engineer  Experience with systems-level programming on at least one major platform (Windows, macOS). Solid programming skills in C/C++. Effective communicator and collaborator, especially in distributed teams. Ability to break down technical work and make steady progress within project timelines. A collaborative mindset and a desire to contribute to team success. Bonus Points Programming experience in Rust. Experience working with Windows and/or macOS APIs at a low level (e.g., Win32, Cocoa). Additional experience with Linux, or macOS internals. Contributions to open source projects. We value a variety of voices within our team and at Mozilla. You don't need to check every box on this list to apply. 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: C #LI-REMOTE Req ID: R3160 Hiring Ranges: Remote Belgium €56.000 — €74.000 EUR

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