Senior Software Engineer - Firefox EnterpriseJoin to apply for the Senior Software Engineer - Firefox Enterprise role at Mozilla.
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 This Team And RoleThe Firefox team is a community of engineers who care deeply about delivering the fastest, friendliest, most usable browser possible. We are responsible for making the things you see in the browser work securely, quickly, and well! The Enterprise team is a cross‑disciplinary team in charge of improving and maintaining Firefox support for large Enterprise deployments. As part of the team, you will be responsible for all things related to OS integration – such as updates, installs, and integrating Firefox with different operating systems – and helping us grow our user base.
Our team is geographically‑distributed, and working in the open is the norm. We contribute to the code driving Firefox on a number of desktop platforms – Windows, Linux, and macOS. A Senior Software Engineer contributes to architectural discussions, and drives feature development within a team. At Mozilla, Senior Engineers are expected to work independently on scoped projects, collaborate closely with peers,



and play a key role in delivering high‑quality software that aligns with team goals.
What You’ll Get To Do
Develop, innovate, and ship the next experience of Firefox through improved integration with the operating system.
Improve the ease of use and security of Firefox in large deployments by developing better administration and monitoring tools.
Improve Firefox functionality by better integration with remote services.
Assess what work supports the team and product roadmap and make insightful recommendations in regards to priorities.
Optimize the quality of Firefox by hunting down and fixing software defects, improving the experience of hundreds of millions of users.
Work with a geographically‑distributed development team.
What You Bring
Experience with systems programming on a major desktop platform (Windows, macOS or Linux).
A solid understanding of C/C++ and some knowledge of Rust.
A solid understanding of JavaScript and typical interactions with the backend (services, REST, ...).
You are an excellent communicator and have participated effectively on a distributed team.
You’re pragmatic about how to move things forward in specific timeframes, including trade‑offs and safeguards when implementing new functionality.
Experience working collaboratively with product managers, project managers, and/or other non‑engineering teams.
Bonus Points
Professional programming experience in Rust.
Development of cross‑platform desktop applications, particularly when this involves low‑level systems programming such as Win32 APIs on Windows, Cocoa APIs on macOS or GTK on Linux.
Previously successfully contributed to an open‑source project.
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.
Quarterly well‑being stipend.
Considerable paid parental leave.
Employee referral bonus program.
Other benefits (life/AD&D;, disability, EAP, etc. – varies by country).
Commitment to diversity, equity, inclusion, and belongingMozilla 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 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 to request accommodation.
We are an equal‑opportunity employer. We do not discriminate on the basis of race, religion, 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.
Seniority levelAssociate
Employment typeFull‑time
Job functionEngineering and Information Technology
IndustriesSoftware Development
Referrals increase your chances of interviewing at Mozilla by 2x.
Hiring RangesRemote – Spain
€57,000 – €83,000 EUR
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📌 Senior Software Engineer - Firefox Enterprise - €57.000 - €83.000 A Year - Remote (Madrid)
🏢 Mozilla
📍 Madrid