Senior Software Engineer, Cryptography (Firefox Security)

About Mozilla: Mozilla Corporation (mozilla.org) is a globally celebrated, non-profit-backed technology trailblazer that has aggressively shaped the internet for the better over the last 25 years. Wholly owned by the non-profit 501(c) Mozilla Foundation, we operate completely free from shareholder profit pressures—beholden only to our core mission of keeping the internet a public, free, and accessible resource for all. Our open-source software assets, including the privacy-minded web browser Firefox, protect over 225 million users worldwide every single month. Alongside thousands of volunteer open-source contributors, Mozillians craft software that empowers citizens to reclaim digital autonomy on their own terms.

Position Overview

We are seeking an exceptionally detail-obsessed, low-level systems specialist, and security-focused Senior Software Engineer to join our core Firefox Security collective under a permanent, full-time remote engagement framework within Germany. Operating inside our foundational cryptography stack, you will step up to claim absolute code creation, security architecture design, and WebPKI protocol maintenance accountability across our open-source native codebase. Shifting completely away from routine website asset logging, basic database form editing, or web-app wrapper modifications, you will run an active cryptographic architecture, multi-threaded optimization, and memory safety analysis laboratory—partnering face-to-face with core systems programmers, browser infrastructure teams, web standards committees, and international engineering leads. This position requires a native systems authority with deep C/C++ proficiency who structures memory allocations fluidly natively using Cybersecurity parameters, evaluates cross-platform stability errors cleanly inside massive cross-compiled codebases, and directs secure web platform features confidently into production browser builds.

Key Responsibilities

• Core Cryptography Architecture Management: Architect, maintain, and iterate Firefox’s central security systems, focusing heavily on cryptographic primitives, public key infrastructure (WebPKI), and security-sensitive web APIs natively utilizing Cybersecurity principles.
• Web Platform Feature Engineering: Build, optimize, and ship standards-based web security features in collaborative loops with the global open-source community, ensuring interoperability and cross-platform alignment.
• Multi-Threaded Performance Optimization: Profile, audit, and debug complex multi-threaded native configurations, identifying and eradicating performance bottlenecks, data races, and memory leaks to enforce extreme browser stability.
• Root-Cause Fault Remediation: Execute systematic investigations into software defects and core architectural vulnerabilities, deploying permanent, long-term engineering fixes across cross-compiled target binaries.
• Design and Planning Contribution: Lead and contribute to complex technical design discussions, preparing detailed tradeoff evaluations regarding memory efficiency, code safety, and runtime velocity.
• Distributed Collaborative Synthesis: Partner productively with highly distributed technical teams to continuously review, test, and document complex updates across multi-language open-source repositories.

Required Skills & Qualifications

• Proven professional history operating as a native systems engineer, security programmer, or core backend infrastructure developer within large, data-sensitive runtime setups.
• Masterful programming proficiency in C/C++, paired with deep foundational knowledge of core computer science primitives and network memory constraints.
• Solid conceptual understanding of modern cryptographic protocols, secure data hashing models, transport encryption protocols, and key exchange layers.
• Exceptional debugging capabilities, showing a robust history diagnosing memory corruption, race conditions, and synchronization failures inside complex multi-threaded environments.
• Excellent verbal and written communication strengths in English, with the capacity to break down intricate lower-level systems challenges to distributed teams.
• Location Context: Position operates under strict remote geographic parameters open exclusively to systems engineering specialists residing permanently within Germany.

Preferred Strategic Indicators (Nice to Have)

• Direct development experience or deep personal engineering familiarity writing safe systems code in Rust.
• Prior practical contribution history to complex open-source infrastructure projects, web standards groups, or browser engine dependencies.

What We Offer

• Attractive, Transparent European Compensation Blueprint: A competitive annual base salary range of €68.000 - €91.000 EUR, complemented by a performance-based corporate bonus structure.
• Full 100% remote workspace flexibility across Germany, augmented by a dedicated one-time home office setup budget stipend.
• Premium corporate benefits package including rich Medical, Dental, and Vision coverage layers for comprehensive health security.
• Generous retirement contribution program featuring 100% immediate vesting schedules to ensure long-term personal financial growth.
• Excellent work-life balance provisions, including considerable paid parental leave tracks, country-specific public holidays, a paid day off on your birthday, and a quarterly wellness stipend.
• Unique quarterly all-company wellness days where the entire international workforce simultaneously takes a coordinated pause to recharge.
• Ongoing learning access through an annual professional development budget designed for advanced technical training, courses, and security conferences.