Senior Software Engineer, WebExtensions

MozillaMozilla·Remote(Remote Canada)
Software Development

WFA Digital Insight

As the demand for tech professionals with expertise in web development and extension management grows, Mozilla is looking for a Senior Software Engineer to join their team. With the rise of remote work, companies are seeking skilled engineers who can balance power, safety, and performance. According to recent statistics, the need for skilled web developers has increased by 25% in the past year, making this role highly sought after. What sets Mozilla apart is their commitment to making the internet better for people, not companies, and their focus on open-source software. Before applying, candidates should be aware of the company's emphasis on collaboration, open-source workflows, and community involvement.

Job Description

About the Role

The Senior Software Engineer, WebExtensions, will play a key role in developing and maintaining the WebExtensions platform, which powers the add-ons ecosystem in Firefox. This platform enables millions of users to customize their browser while keeping safety and performance at the forefront. As a member of the WebExtensions team, you will work closely with other engineers, product managers, and QA to deliver features end-to-end and ensure that extensions remain reliable across Firefox.

The WebExtensions platform is a crucial part of Mozilla's mission to make the internet better for people. By joining this team, you will have the opportunity to work on complex systems, create experiences that balance developer power with user trust, and collaborate with experts across Mozilla to advance cross-browser compatibility and standardization.

Mozilla is a non-profit-backed technology company that has shaped the internet for the better over the last 25 years. The company is committed to making the internet a better place for people, not companies, and is focused on open-source software and community involvement.

What You Will Do

  • Implement and maintain WebExtensions APIs and Addon Management, balancing power, safety, and performance, as well as user interfaces in Firefox.
  • Debug and fix issues affecting extensions in Firefox.
  • Collaborate with product managers, QA, and the AMO engineering team to deliver features end-to-end.
  • Contribute to Mozilla-owned extensions and system add-ons.
  • Participate in open source workflows: code reviews, pull requests, and discussions in Bugzilla/GitHub.
  • Support extension developers by helping diagnose issues and improving tooling/documentation.
  • Work on evolving extension capabilities and building UI features in Firefox that make extensions clear and manageable for users.
  • Collaborate with experts across Mozilla to advance cross-browser compatibility and standardization.
  • Ensure that extensions remain safe, powerful, and reliable for developers and millions of Firefox users.

What We Are Looking For

  • 4+ years of professional experience in software development.
  • Strong proficiency in JavaScript, DOM APIs, HTML, and CSS.
  • Experience with web development, extension management, and add-on development.
  • Knowledge of open-source software and community involvement.
  • Strong problem-solving skills and attention to detail.
  • Ability to work collaboratively in a remote team environment.
  • Experience with code reviews, pull requests, and discussions in Bugzilla/GitHub.

Nice to Have

  • Experience with Gecko platform and Firefox development.
  • Knowledge of cross-browser compatibility and standardization.
  • Familiarity with open-source workflows and community involvement.
  • Experience with add-on development and extension management.

Benefits and Perks

  • Competitive salary and benefits package.
  • Opportunity to work on complex systems and create experiences that balance developer power with user trust.
  • Collaborative and dynamic work environment.
  • Flexible working hours and remote work options.
  • Professional development opportunities and support for ongoing learning and growth.
  • Access to the latest technologies and tools.
  • Opportunity to work on open-source software and contribute to the community.

How to Stand Out

  • Be prepared to showcase your experience with web development, extension management, and add-on development.
  • Highlight your knowledge of open-source software and community involvement.
  • Emphasize your problem-solving skills and attention to detail.
  • Showcase your ability to work collaboratively in a remote team environment.
  • Be prepared to discuss your experience with code reviews, pull requests, and discussions in Bugzilla/GitHub.
  • Research Mozilla's mission and values, and be prepared to discuss how your skills and experience align with them.

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