Senior Software Engineer

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, and Pocket, a service for keeping up with the best content online. 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:

The Relay Engineering Team is committed to building tools that empower users to manage their online identities and maintain their privacy. We work on various ongoing and upcoming projects, ranging from sustaining existing products to integrating new solutions for scalability and security. We are a highly collaborative team that thrives on innovation, feedback, and continuous improvement.

As a Senior Software Developer at Mozilla, you will be an integral part of the Relay Engineering Team, responsible for building and maintaining key backend systems and supporting frontend implementations. You’ll work on projects that focus on privacy and security, including features like email and phone number masking, which are central to our users’ online safety.

What you’ll do: 

• Lead frontend development, working with JavaScript, Typescript, React, and next.js
• Contribute to backend development when required, using Python, Django, and PostgreSQL
• Design, implement, and maintain code for email and phone number masking using AWS and Twilio APIs, focusing on security and privacy, in alignment with Mozilla Relay’s core objectives.
• Periodically rotate into a Base Load Engineer (BLE) role: handling releases, dependency updates, and incoming work requests, including bug reports and customer support requests.
• Collaborate with DevOps (SRE) to manage and maintain production environments, ensuring robust deployment processes.
• Monitor and optimize system performance, leveraging tools such as Grafana, Sentry, and BigQuery to track metrics, tracebacks, and data insights.
• Partner with cross-functional teams to align on project goals, ensure seamless frontend-backend integration, and contribute to API design and evaluations.
• Participate in code reviews to maintain high standards of code quality and system reliability.
• Participate in security and privacy reviews, ensuring that all data protection measures, including email alias management and phone number masking, meet compliance standards.

What you’ll bring: 

• 7+ years of experience in software development with a strong focus on frontend technologies.
• In-depth knowledge of JavaScript, Typescript, React, next.js, SCSS,  and a willingness to contribute to full-stack development when needed.
• Experience in configuring, implementing, and maintaining Google Analytics 4 (GA4) to track and analyze user behavior.
• Proficiency with back-end technologies including Python, Django, and PostgreSQL
• Experience managing cloud platforms like Heroku, AWS, or GCP, with a strong understanding of DevOps practices and SRE collaboration.
• Understanding of privacy and security principles.
• Experience with monitoring tools such as Grafana, Sentry, and BigQuery, including data-driven optimization and troubleshooting.
• Strong communication skills and ability to collaborate across engineering, product, and operations teams.
• Experience mentoring junior engineers and driving technical excellence in code quality, testing, and process improvements.

Bonus Points for experience with:

• REST API serving millions of clients
• WebExtensions
• Twilio
• AWS: SES, S3, SNS, SQS
• Email tech: DMARC, SPF, DKIM, FBL

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 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

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Req ID: R2688

Hiring Ranges:

US Tier 1 Locations$137,000—$199,000 USDUS Tier 2 Locations$126,000—$183,000 USDUS Tier 3 Locations$116,000—$169,000 USD Apply