--- title: 'Senior Software Engineer, OS Integration at Mozilla' canonical: 'https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-spain-dgtyey1ht4v3' type: 'job' last_seen: '2026-11-12' --- # Senior Software Engineer, OS Integration at Mozilla - **Company:** Mozilla - **Location:** Spain - **Compensation:** €58k–€77k - **Work type:** remote - **Posted:** 2026-11-11 - **Last confirmed live:** 2026-11-12 - **Apply:** https://job-boards.greenhouse.io/mozilla/jobs/8367114 ## Job description 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. About the OS Integration team: The OS Integration team ensures Firefox works well with the host operating system and environment. We’re a distributed team with expertise in Windows, macOS, and Linux-based operating systems. Our responsibilities include developing fixes and improvements for Firefox related to Windows, macOS, and Linux environments. This might include integration with a new OS feature or fixing an OS-specific user interface bug. Other responsibilities include native crash reporting, OS abstraction layers, sandboxing, hardening, updater, and enterprise DLP support. About the role: As a member of the OS Integration team, you’ll develop fixes, improvements, and new features for Firefox. In many cases work may be cross-platform or have a cross-platform component. This role will include maintenance and development of the installer and updater of Firefox. You’ll contribute to the team through code review and discussion. What you’ll do: - Improve the quality of Firefox and other Mozilla products by debugging and fixing software defects, improving the browsing experience for hundreds of millions of users. - Contribute to new features and improvements. - Break down tasks and work with others to deliver solutions. - Collaborate with experienced software engineers. - Perform code reviews and provide technical direction. - Work with a geographically-distributed development team. - Interact with teams throughout the organization. What you’ll bring: - 5+ years of overall software engineering experience - Strong knowledge of C and C++ - Experience with desktop application development on Windows, macOS, or Linux with C++. - Knowledge of web technologies such as Javascript and HTML. - Knowledge of secure coding practices and memory safety concerns. - Strong problem-solving and debugging skills. - Written and verbal communication skills with a collaborative mindset. - Willingness to work effectively in a distributed team environment. - Commitment to our values: - Play to win - Build for People first - Engage Evidence over Ego - Decide and Deliver - Ship, learn and repeat Bonus Points for experience with: - Installer and/or Updater development on any OS - Windows internals like the BITS server or MSIX packages - Open-source contributions or personal engineering projects What you’ll get: - Generous performance-based bonus plans to all eligible employees - we share in our success as one team - Rich medical, dental, and vision coverage - 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 - Considerable paid parental leave - Employee referral bonus program - Other benefits (life/AD&D, disability, EAP, etc. - varies by country) ## 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 ## #LI-REMOTE Req ID: R3288 Hiring Ranges: Remote Spain €58.000—€77.000 EUR ## About Mozilla ## Company Overview - **One-liner**: Mozilla is a global nonprofit-backed technology organization that builds privacy-first browsers, AI tools, and internet health initiatives to keep the internet open and accessible to all. - **Entity Type**: Private (nonprofit foundation with a for-profit subsidiary — Mozilla Corporation) - **Headquarters**: San Francisco, California, USA (remote-first globally) - **Founded**: 1998 (Mozilla Project); 2005 (Mozilla Corporation) - **Founders**: Originally founded by Netscape staff and the open-source community; key early leaders include Mitchell Baker (current CEO of Mozilla Corporation) and Brendan Eich (creator of JavaScript) ## Core Business - **Primary industries**: Internet software & services, browser technology, digital privacy, artificial intelligence, online advertising technology - **Target customers**: B2C (individual users — Firefox browser, Pocket, VPN, Relay); B2B (advertisers and publishers via Anonym); developers (open-source tools, MDN Web Docs, AI developer tools) - **Mission statement**: "To ensure the internet is a global public resource, open and accessible to all." — Mozilla Manifesto ## Products & Services - **[Firefox Browser](https://www.mozilla.org/en-US/firefox/)**: Privacy-focused web browser with tracking protection, available on desktop and mobile. Core product. - **[Mozilla VPN](https://www.mozilla.org/en-US/products/vpn/)**: Virtual private network service for online privacy. - **[Firefox Relay](https://relay.firefox.com/)**: Email masking service to protect user identities. - **[Mozilla Pocket](https://getpocket.com/)**: Content discovery and read-later service. - **[Mozilla Monitor](https://monitor.mozilla.org/)**: Data breach alert and personal data removal service. - **[Mozilla.ai](https://mozilla.ai/)**: Open-source AI developer tools and trustworthy AI initiatives. - **[Anonym](https://anonym.co/)**: Privacy-preserving digital advertising measurement platform (acquired by Mozilla in 2022). - **[Fakespot](https://www.fakespot.com/)**: AI-powered tool to detect fake reviews and counterfeit products (acquired by Mozilla). - **[MDN Web Docs](https://developer.mozilla.org/)**: Industry-standard web development documentation and learning platform. - **[Mozilla Ventures](https://mozilla.vc/)**: Venture capital arm investing in responsible tech startups. ## Market Standing - **Valuation/Market Cap**: Not publicly disclosed (private, nonprofit-backed organization) - **Key Revenue**: Approximately $593 million in total revenue (2022, latest publicly available — Mozilla Foundation annual report). The majority comes from search partnerships (primarily Google). - **Notable Partners**: Google (search partnership, revenue driver), Meta (via Anonym), Amazon, eBay, and major ad-tech platforms. - **Growth Signals**: Mozilla has aggressively expanded through acquisitions (Anonym, Fakespot, Pulse, Active Replica); launched Mozilla.ai to bet on open-source AI; growing headcount across engineering, AI, and privacy product teams. As of 2024, the organization employs roughly 800–900+ people globally. ## Competitive Advantages - **Brand trust and mission**: Uniquely positioned as a "not-for-profit" tech company — no shareholder pressure to maximize profit at user expense. Consistently ranked among most trusted tech brands. - **Privacy-first product DNA**: All products are built with privacy and security as core features, not afterthoughts — a strong differentiator vs. Big Tech competitors. - **Open-source foundation**: Transparent codebase, community-driven development, and strong developer credibility (MDN Web Docs is the gold standard for web dev learning). - **Diverse revenue streams**: Beyond browser search deals, Mozilla is building a portfolio of subscription products (VPN, Relay, Monitor Plus) and ad-tech (Anonym) to reduce single-partner dependency. - **Talent and culture**: Decades of experience in remote-first, asynchronous, globally distributed work. Strong engineering culture with deep expertise in privacy, security, and web standards. ## Strategic Focus - **AI with trust**: Building open-source AI tools and models through Mozilla.ai, emphasizing transparency, privacy, and user agency — contrasting with closed, extractive AI from Big Tech. - **Product diversification**: Reducing reliance on search revenue by scaling subscription products (VPN, Monitor, Relay) and ad-tech platform (Anonym). - **Internet health advocacy**: Continuing policy work on data privacy, antitrust, and digital rights through the Mozilla Foundation. - **Firefox revitalization**: Modernizing the browser with new features (vertical tabs, AI-powered tools, improved performance) to regain market share. - **Acquisition integration**: Absorbing and scaling recent acquisitions (Fakespot for e-commerce trust, Anonym for privacy-first advertising). ## Why Work Here - **Culture**: "Remote-first" company with a strong emphasis on asynchronous work, work-life balance, and global collaboration. The culture is mission-driven, collaborative, and values "responsible participation" — generosity and kindness in communication. [mozilla.org](https://www.mozilla.org/en-US/careers/) - **Benefits (US employees)**: - **Health**: 100% premium coverage for medical, dental, and vision for employees and dependents. - **Mental health**: Free therapy and coaching sessions. - **Time off**: 12+ paid holidays, generous vacation and sick leave (accrued from day one), quarterly company-wide wellness days, and your birthday off. - **Parental leave**: 26 weeks paid for childbearing parents, 12 weeks paid for non-childbearing parents. - **Remote-first**: Work from anywhere with a strong stipend for home office setup. [mozilla.org](https://www.mozilla.org/en-US/careers/) - **Engineering culture**: Engineers work on "some of the most interesting challenges facing the internet today — privacy, security, decentralization, access, convenience, compatibility." The Data Organization is at the forefront of using data to guide product decisions while respecting user privacy. [mozilla.org](https://www.mozilla.org/en-US/careers/) - **Diversity & Inclusion**: Mozilla explicitly states it wants to be "a place where everyone can do their best work" and that "diverse perspectives and experiences result in better solutions." They publish transparency data on their progress. - **Open roles**: As of mid-2025, Mozilla has ~90 open positions across engineering (Front-End, Machine Learning, Fullstack), product management, data analytics, marketing, and infrastructure. Key teams hiring include Firefox, Anonym, Fakespot, and Mozilla.ai. [greenhouse.io](https://job-boards.greenhouse.io/mozilla?gh_src=e5ad1d6b1us) ## Sources 1. [Mozilla Careers Page](https://www.mozilla.org/en-US/careers/) 2. [Mozilla About Page](https://www.mozilla.org/en-US/about/) 3. [Mozilla Job Board (Greenhouse)](https://job-boards.greenhouse.io/mozilla?gh_src=e5ad1d6b1us) 4. [Mozilla.org Homepage](https://www.mozilla.org/en-US/) 5. [Mozilla Open Positions List](https://www.mozilla.org/en-US/careers/listings/) ## Other roles at Mozilla - [Field Marketing Manager, Firefox Enterprise](https://feeny.ai/job/field-marketing-manager-firefox-enterprise-mozilla-france-wkce2sv25m4b) — France - [Field Marketing Manager, Firefox Enterprise](https://feeny.ai/job/field-marketing-manager-firefox-enterprise-mozilla-remote-rtm760w56azw) - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-finland-mwfw1w5kncrg) — Finland - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-united-kingdom-j4j2f693xz5v) — United Kingdom - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-sweden-ev9gq133v4fx) — Sweden - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-netherlands-397wyz8ktgk9) — Netherlands - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-belgium-pbea8qs8w8ty) — Belgium - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-germany-hmwevkffzg20) — Germany - [Senior Software Engineer, OS Integration](https://feeny.ai/job/senior-software-engineer-os-integration-mozilla-france-rhebdnnk344j) — France - [Staff Software Engineer, Browser (New Products)](https://feeny.ai/job/staff-software-engineer-browser-new-products-mozilla-canada-16502zkpc02x) — Canada