Staff Site Reliability Engineer, Tools & Systems

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 role:

We are looking for an experienced and versatile software engineer to work on the tools and systems that support Firefox engineering.

This is a broad software engineering role spanning internal engineering systems, developer tooling, workflow automation, and the infrastructure required to operate them. We are looking for an engineer with strong software development skills and meaningful experience deploying and operating production systems.

Our Cloud Engineering teams provide shared platforms and foundational services, while engineering teams own the applications and services they run on them. A key part of this role is helping teams succeed in that model by solving difficult operational problems, establishing standards and patterns, and building tooling and automation that makes systems easier to operate. You will also contribute directly to the software, tools, and systems that support Firefox engineering.

You will work across projects and technical domains, joining teams or existing efforts when needed and independently taking on problems that require focused ownership.

We build in the open. Open source is fundamental to how we work, and contributing back to the broader open-source ecosystem is an important part of the role.

What you'll do:

• Design, build, deploy, and operate software and systems supporting Firefox engineering.
• Contribute to developer tooling, CI/CD, workflow automation, and AI-assisted development tools.
• Own complex technical problems end-to-end across software, cloud, and operational layers, improving reliability, performance, observability, and cost efficiency.
• Work with Firefox engineering, Cloud Engineering, IT, and other teams to solve problems that span technical and organizational boundaries.
• Use telemetry, metrics, and data analysis to investigate problems and guide engineering decisions.
• Contribute to architecture and technical strategy, identifying recurring problems and solutions that can be applied across teams.

What you'll bring:

Strong software engineering skills and substantial hands-on experience deploying and operating production systems are core requirements for this role. We do not expect you to be an expert in every technology or domain listed below.

• Strong programming skills in languages such as Python or JavaScript/TypeScript. Experience with C++ or Rust is useful.
• Experience building and deploying and operating production systems in cloud environments, including utilizing infrastructure as code such as Terraform.
• Experience across several areas such as CI/CD, containers and orchestration, networking, databases, observability, or developer tooling.
• Experience using data, telemetry, and metrics to investigate technical problems and make decisions.
• Familiarity with modern AI-assisted development tools and an understanding of their capabilities, limitations, and appropriate use.

How you work:

• You are comfortable jumping into unfamiliar systems and getting them into a sustainable state.
• You enjoy moving across projects and technical domains, taking ownership of problems and looking for patterns that make the next one easier to solve.
• You work effectively across disciplines and can translate between software, infrastructure, and operational concerns.
• You combine hands-on engineering with systems thinking and longer-term technical judgment.
• You communicate openly, consistently, and respectfully, and enjoy teaching and helping others build skills in unfamiliar technical areas.

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)

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 [email protected] 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: C

Req ID: R3254

Hiring Ranges:

Remote Spain

€76.000—€101.000 EUR