Senior Software Engineer, Firefox Security

🕒 October 15

🇬🇧 United Kingdom – Remote

💵 £66k - £87k / year

⏰ Full Time

🟠 Senior

🧑‍💻 Full-stack Engineer

👻 Ghost score 0%

What it means: how likely this posting is sitting open without active hiring.How to read it: 60% or higher means we think this is a ghost. Lower scores are less of a worry.How we score it: age, reposts, open roles vs team size, how fast jobs close, and whether pay is listed.Fine print: an estimate from public data, not a judgment of the company. Real jobs can score high, so treat it as a hint, not a fact.

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Mozilla

WebsiteLinkedInAll Job Openings

501 - 1000 employees

Founded 1998

👥 B2C

🔒 Cybersecurity

B2C • Cybersecurity • Software

Mozilla is a non-profit organization dedicated to promoting an open and accessible internet. They are the makers of the popular Firefox browser, which emphasizes user privacy, speed, and control. Mozilla also offers a range of products that focus on internet security and privacy, including Mozilla VPN, Firefox Relay, and Mozilla Monitor. Additionally, the organization is involved in open-source projects, AI innovation, and advocating for digital rights. Mozilla aims to empower users with trustworthy technology and policies that protect privacy, support open-source AI development, and foster accountability for tech companies.

📋 Description

• Design, implement, test, and ship security and hardening features that strengthen Firefox’s security posture for enterprise users • Contribute to and drive security architecture improvements across multiple operating systems, including 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 • Experience with memory and performance challenges • Familiarity with web technologies: HTML, CSS, and JavaScript • Interest or experience in Rust • Ability to work effectively within large, complex, multi-language codebases • Experience working with distributed teams • Ability to communicate technical ideas clearly in writing and conversation

🏖️ Benefits

• 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)