Mozilla.ai

Firefox OS Integration: Windows Senior Software Engineer

11 December 2025
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Deadline date:
£137000 - £183000 / year

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 OS Integration team ensures Firefox and other Gecko-based products harmonize well with the host operating system and environment. We work on components of Firefox including, but not limited to, native crash reporting, OS abstraction layers, platform-specific features, sandboxing and hardening. We’re a distributed team with expertise in Windows, macOS, and Linux-based operating systems.

In this role, you will be a member of the OS Integration team specializing in the Windows platform. What you’ll do: Improve the quality of Firefox on Windows by developing fixes and improvements, improving the user experience for hundreds of millions of users. Help develop and ship major new Firefox features on Windows.

Work on cross-platform features and projects for other platforms such as macOS, Linux, and Android as needed. Collaborate with other teams by providing code review and technical direction.

Work with a geographically-distributed development team. What you’ll bring: A degree in Computer Science or a related field or comparable work experience. A solid understanding of C and C++.

Demonstrated experience with low-level systems programming on Windows. Knowledge of web technologies such as Javascript, HTML, and CSS. Strong problem-solving and debugging skills.

Written and verbal communication skills with a collaborative mindset. Willingness to work effectively in a distributed team environment. Commitment to our values:Welcoming differencesBeing relationship-mindedPracticing responsible participationHaving gritWhat you’ll get:Generous performance-based bonus plans to all eligible employees – we share in our success as one teamRich medical, dental, and vision coverageGenerous retirement contributions with 100% immediate vesting (regardless of whether you contribute)Quarterly all-company wellness days where everyone takes a pause togetherCountry specific holidays plus a day off for your birthdayOne-time home office stipendAnnual professional development budgetQuarterly well-being stipendConsiderable paid parental leaveEmployee referral bonus programOther 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.


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