Senior Software Engineer, Firefox Security

Mozilla; United Kingdom; Remote; GBP 85,000 - 120,000; Full time

Benefits offered by this job

Bonus plans

Retirement contributions

Wellness days

Holiday + birthday

Home office stipend

Professional development budget

Well-being stipend

Parental leave

Referral program

Other benefits

Job summary

Mozilla is seeking a Senior Software Engineer, Firefox Security, to design and implement advanced security features for enterprise users. You will contribute to Firefox’s security architecture across multiple operating systems, collaborating with distributed teams to investigate issues and deliver robust fixes.

You will also work on improving browser reliability, performance, and memory usage in a complex, multi-language codebase, with a strong emphasis on security fundamentals and modern web

Qualifications

• 3+ years of low-level software engineering experience.
• Strong proficiency in C and/or C++.
• Solid understanding of security fundamentals.
• Experience diagnosing issues in multithreaded, cross-platform native applications.
• Familiarity with HTML, CSS, JavaScript; interest or experience in Rust.
• Ability to collaborate effectively with distributed teams and communicate clearly.

Responsibilities

• Design, build and implement security features for enterprise users.
• Advance Firefox security architecture across multiple OSes.
• Investigate security issues, identify root causes, and deliver robust fixes.
• Improve browser reliability, performance, and memory usage in a complex environment.

Skills

C/C++

Security fundamentals

Multithreading

Web technologies

Rust interest

Distributed collaboration

Job description

Senior Software Engineer, Firefox Security

at Mozilla Corporation Team: Firefox Locations: Remote UK, Remote Germany, Remote France, Remote Finland, Remote Belgium, Remote Spain, Remote Netherlands, Remote Sweden

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)