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Senior Software Engineer, WebExtensions

1 hour, 22 minutes ago
United Kingdom
Full-time
Mid Level
Software Engineer
Software Development
Android C++ CSS GitHub HTML JavaScript Rust
Apply Now
Mozilla

Mozilla

Mozilla, the maker of Firefox, is a non-profit organization ensuring an open, safe, and accessible internet for all users worldwide.

Internet Software & Services
251-1K
Founded 2005
$2M raised
View All Jobs 55

Description

  • Implement and maintain WebExtensions APIs, Addon Management, and related Firefox user interfaces.
  • 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 development workflows, including code reviews, pull requests, and Bugzilla/GitHub discussions.
  • Support extension developers by diagnosing issues and improving tooling and documentation.
  • Work deep in the Gecko platform to evolve extension capabilities.
  • Help advance cross-browser compatibility and standards alignment.

Requirements

  • 4+ years of professional experience in software development.
  • Strong proficiency in JavaScript, DOM APIs, HTML, and CSS.
  • Familiarity with modern browser architecture and debugging tools.
  • Experience with API design and integration.
  • Ability to navigate and learn from large codebases.
  • Strong communication skills and experience collaborating in distributed teams.
  • Experience with Firefox internals, C++, or Rust is preferred.
  • Familiarity with Android or GeckoView development is preferred.
  • Knowledge of web security principles is preferred.
  • Contributions to open source projects, especially browser or extension development, are preferred.

Benefits

  • £66,000 to £87,000 GBP remote UK hiring range.
  • Generous performance-based bonus plan for eligible employees.
  • Rich medical, dental, and vision coverage.
  • Generous retirement contributions with 100% immediate vesting.
  • Quarterly company wellness days and a quarterly well-being stipend.
  • Country-specific holidays plus a day off for your birthday.
  • One-time home office stipend and an annual professional development budget.
  • Considerable paid parental leave and an employee referral bonus program.

Interested in this position?

Apply directly on the company website

Apply Now

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