Senior Software Engineer, Firefox Security
Remote Netherlands · Remote · EUR 66-88 · 3+ years experience · Remote · Posted Oct 15, 2026
At a glance
- Experience
- 3+ years experience
- Workplace
- Remote
- Location
- Remote Netherlands · Remote
- Salary
- EUR 66-88
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 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: D
About the role
- Mozilla Corporation is seeking a Senior Software Engineer for Firefox Security to design, build, and implement security and hardening features for enterprise users.
- The role involves advancing Firefox's security architecture across multiple operating systems and improving core security mechanisms.
Responsibilities
- Design, implement, test, and ship cutting-edge security features that strengthen Firefox's security posture.
- Contribute to and drive cutting-edge improvements to Firefox’s core security posture, by building privilege isolation and moving trust boundaries.
- Improve Firefox’s core security mechanisms including cryptographic protocols, WebPKI, and security-sensitive web APIs.
- Work across teams to investigate security issues, identify root causes, and deliver robust, maintainable fixes.
- Diagnose and resolve issues affecting stability, correctness, performance, and memory usage in a complex, multithreaded environment.
Requirements
- 3+ years of experience in low-level software engineering.
- Strong proficiency in C and/or C++.
- Solid understanding of 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).
- Ability to work effectively within large, complex, multi-language codebases.
- Experience working with distributed teams and communicating technical ideas clearly in writing and conversation.
Preferred qualifications
- Interest or experience in Rust
Benefits
- Generous performance-based bonus plans
- Generous retirement contributions with 100% immediate vesting
- Quarterly all-company wellness days
- 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)
Workplace
- Remote Netherlands
- Remote Germany
Skills
- C
- C++
- Rust
- HTML
- CSS
- JavaScript
