Senior Software Engineer, Firefox Security

Thunderbird; España; À distance; EUR 66 000 - 88 000; Plein temps

Avantages offerts par ce poste

Performance bonus

Retirement contributions

Wellness days

Birthday holiday

Home office stipend

Professional development budget

Well-being stipend

Parental leave

Employee referral bonus

Other benefits

Résumé du poste

Mozilla Corporation is seeking a Senior Software Engineer, Firefox Security, to design and implement enterprise security features that strengthen Firefox’s security posture across multiple operating systems. You will drive improvements to core security mechanisms and collaborate with teams to investigate issues and deliver robust fixes.

The role emphasizes memory management, performance, and multithreaded reliability, with opportunities to contribute to cryptographic protocols, WebPKI, and

Qualifications

• 3+ years of experience in low‑level software engineering with strong security fundamentals.
• Experience diagnosing and resolving issues in multithreaded, cross‑platform native applications including memory and performance challenges.
• Familiarity with web technologies (HTML, CSS, JavaScript) and interest or experience in Rust; ability to work within large, multi‑language codebases.
• Effective collaboration and communication across distributed teams.

Responsabilités

• Design, build and implement security features to strengthen Firefox’s security posture.
• Advance Firefox’s security architecture across multiple operating systems and strengthen core security mechanisms.
• Investigate security issues, identify root causes, and deliver robust, maintainable fixes.
• Diagnose and resolve issues affecting stability, performance, and memory usage in a complex, multithreaded environment.

Connaissances

Systems programming

Security knowledge

Debugging and problem-solving

Communication

Outils

C/C++

Rust

Web technologies (HTML/CSS/JS)

Description du poste

Senior Software Engineer, Firefox Security

at Mozilla Corporation

Team: Firefox

Locations: Remote Sweden, Remote UK, Remote France, Remote Germany, Remote Finland, Remote Belgium, Remote Spain, Remote Netherlands

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.

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.

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 [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.

Hiring Ranges

• Remote Netherlands

€66.000—€88.000 EUR

• Remote Sweden
• Remote UK
• Remote France
• Remote Germany
• Remote Finland
• Remote Belgium
• Remote Spain
• Remote Netherlands

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