Key Skills

Job Description

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Cookie settings Products Firefox browsers Mozilla VPN Mozilla Monitor Firefox Relay MDN Plus Thunderbird 0DIN Tabstack Otari All products About us Our Mission About Mozilla The Mozilla Manifesto Get Involved Blog Our Work Mozilla Foundation Mozilla.ai Mozilla Ventures Mozilla Advertising Mozilla Builders Mozilla New Products Mozilla Careers Menu Overview Diversity and Inclusion Benefits Teams Locations Job Listings Senior Software Engineer, Firefox Security at Mozilla Corporation Team: Firefox Locations: Remote Netherlands, Remote Germany, Remote UK, Remote Belgium, Remote Spain, Remote Finland, Remote Sweden, Remote France Remote Netherlands Remote Germany Remote UK Remote Belgium Remote Spain Remote Finland Remote Sweden Remote France 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. What You’ll Do Design, build and implement security and hardening features for enterprise users: Design, implement, test, and ship cutting-edge security features that strengthen Firefox’s security posture. Advance Firefox’s security architecture across multiple operating systems: Contribute to and drive cutting-edge improvements to Firefox’s core security posture, by building privilege isolation and moving trust boundaries or Strengthen Firefox’s security architecture: Improve Firefox’s core security mechanisms including cryptographic protocols, WebPKI, and security-sensitive web APIs. Contribute to our security initiatives: Work across teams to investigate security issues, identify root causes, and deliver robust, maintainable fixes. Improve browser reliability and performance: Diagnose and resolve issues affecting stability, correctness, performance, and memory usage in a complex, multithreaded environment. What You’ll Bring Systems programming experience and security knowledge: 3+ years of experience in low-level software engineering, strong proficiency in C and/or C++, and a solid understanding of security fundamentals. Debugging and problem-solving skills: Experience diagnosing and resolving issues in multithreaded, cross-platform native applications, including memory and performance challenges. Web platform and modern systems experience: Familiarity with web technologies (HTML, CSS, JavaScript) and interest or experience in Rust; ability to work effectively within large, complex, multi-language codebases. Effective collaboration and communication: Experience working with distributed teams and communicating technical ideas clearly in writing and conversation. What You’ll Get Generous performance-based bonus plans to all eligible employees - we share in our success as one team 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 [email protected] 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: R3247 Hiring Ranges Remote Spain €58.000—€77.000 EUR Remote Netherlands Remote Germany Remote UK Remote Belgium Remote Spain Remote Finland Remote Sweden Remote France 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 1000+ paid staff from over 30 countries Thousands of volunteer contributors across six continents 2 global offices: Berlin and Toronto 9 coworking space locations: San Francisco, San Mateo, London, Paris, Portland, Tulsa, Vancouver, Chicago, and Bellevue Hundreds of home offices globally Our benefits are world-class Flexible work environment (majority 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 Company Leadership Press Center Careers Merch Store Contact Support Product Help File a Bug Localize Mozilla Security Developers Developer Edition Enterprise Tools MDN Firefox Release Notes Follow @Mozilla Bluesky (@mozilla.org) Instagram (@mozilla) LinkedIn (@mozilla) TikTok (@mozilla) Spotify (@mozilla) Follow @Firefox Bluesky (@firefox.com) Instagram (@firefox) YouTube (@firefoxchannel) TikTok (@firefox) Donate All languages Language English (Canadian) English (British) English Donate to the not-for-profit Mozilla Foundation. 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Core Responsibilities

Design, implement, test, and ship Firefox security and hardening features, including improvements to privilege isolation, trust boundaries, cryptographic protocols, WebPKI, and security-sensitive web APIs. Investigate security issues across teams and resolve reliability, correctness, performance, and memory problems in a complex, multithreaded, cross-platform environment.

Requirements

Requires at least three years of low-level software engineering experience, strong C and/or C++ proficiency, and a solid understanding of security fundamentals. Candidates should be able to debug multithreaded cross-platform native applications, work in large multi-language codebases, have familiarity with web technologies and interest or experience in Rust, and communicate effectively with distributed teams.

Benefits

• Performance-Based Bonus
• Retirement Contributions
• Wellness Days
• Country-Specific Holidays
• Birthday Leave
• Home Office Stipend
• Professional Development Budget
• Well-Being Stipend
• Paid Parental Leave
• Employee Referral Bonus
• Life Insurance
• Accidental Death and Dismemberment Insurance
• Disability Benefits
• Employee Assistance Program