OverviewAs a Security Engineer, you design and implement security features that strengthen Firefox, across multiple operating systems. You collaborate to improve Firefox's core security posture, including cryptographic protocols and WebPKI, while addressing issues and ensuring reliability in a complex, multithreaded browser environment. You will work with cross-functional teams to ship robust fixes and drive security initiatives.

This role offers meaningful impact in advancing a privacy-minded, open-source web platform. Compensaciones / Beneficiosgenerous performance-based bonus retirement contributions with immediate vesting quarterly wellness days holiday policies plus birthday off home office stipend annual professional development budget ResponsabilidadesDesign, implement, test,



and ship security features for enterprise users to strengthen Firefox security Advance Firefox security architecture across operating systems with privilege isolation and trust boundary improvements Strengthen core security mechanisms including cryptographic protocols, WebPKI, and sensitive web APIs Collaborate across teams to investigate security issues, identify root causes, and deliver robust fixes Diagnose and improve browser reliability, performance, and memory usage in a multithreaded environment Requisitos principales3+ years of low-level software engineering Proficiency in C and/or C++ Solid understanding of security fundamentals Experience debugging multithreaded, cross-platform native applications Familiarity with web technologies (HTML, CSS, JavaScript) and interest/experience in Rust Ability to work effectively within large, multi-language codebases Strong communication and collaboration in distributed teams effective collaboration clear written and verbal communication problem-solving C/C++ security fundamentals multithreading

📌 Senior Software Engineer, Firefox Security - España (Valladolid)
🏢 Mozilla
📍 Valladolid