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. 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.

Addons.mozilla.org (AMO) is the foundation of the Firefox add‑ons ecosystem. It’s a showcase for developers to publish and grow their extensions, and a place of discovery for millions of users who customize Firefox to make it their own. AMO carries the responsibility of building a great, secure, and trustworthy experience for both users and developers.

As a Senior Software Engineer, you’ll bring a passion for crafting beautiful, accessible experiences to AMO. You’ll work closely with designers and product managers to turn ideas into polished features, modernize the platform and its architecture, and see your work reach millions of people around the world.

• Design, build, and refine frontend experiences in AMO and Dev Hub, ensuring they are fast, accessible, and user‑friendly.
• Contribute to modernization and improvements in architecture and maintainability.
• Help keep the platform safe and trustworthy, with attention to security and user trust.
• Step in to resolve issues impacting users and developers, from small bugs to larger incidents.
• Collaborate with designers, product managers, QA, and community contributors to deliver end‑to‑end improvements.
• Contribute in the open through pull requests, code reviews, and discussions.

• Frontend and full stack development:
  React/Type Script frontends, Django backend, MySQL datastore.
• Platform reliability: deployments, monitoring, and incident response on Google Cloud.
• Feature development: submission flows, trust and safety signals, and Dev Hub modernization.
• Open collaboration:
  We work in the open, with contributions from Mozilla staff and community members.

• 4+ years of professional experience building modern web applications.
• Proficiency in React, JavaScript/Type Script, HTML, and CSS, with strong debugging and testing skills.
• Familiarity with Python/Django or similar backend frameworks.
• Understanding of web security principles and practices.
• Awareness of accessibility, responsive design, and API integration.
• Strong collaboration and communication skills in a distributed team environment.
• Comfortable working in an environment that includes contributions from both staff and the open‑source community.
• Commitment to our values:
• Welcoming differences
• Being relationship‑minded
• Practicing responsible participation
• Having grit

• Experience with relational databases such as MySQL.
• Exposure to cloud infrastructure (Google Cloud or similar).
• Contributions to open source projects.
• Other front end stacks such as Jinja
  2.
• Experience mentoring or supporting junior developers.

• 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).

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,…