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Contract Software Engineer - DOM Core Firefox/Gecko

Mozilla · posted 11 days ago

Remote RS 50 seniorjavascript

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At a glance

Location
Remote
Posted
Sep 22, 2026
Auto-expires by
Oct 10, 2026 (if not re-listed at source)

Remote Score for Mozilla

50/100 · we score companies against a 10-point editorial rubric. How we score →

  • Fully distributed
  • Async-first culture
  • Timezone-flexible
  • Equal remote compensation
  • Home office stipend
  • Coworking allowance
  • Protected focus time
  • Public handbook
  • Transparent salaries
  • Distributed leadership

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About this role (from Mozilla's posting)

The role You will help the Firefox DOM Core team improve the health of the Session History area. You will write tests to improve the coverage; you will fix tests and/or problems to improve the Gecko correctness. Responsibilities Write Web-Platform tests to improve the coverage, and Gecko mochitests as needed Fix the problems and pass the tests to improve the Gecko correctness Work through code review with the relevant Gecko module owners and iterate to landing Definition of done Improved Session History test coverage and code correctness in Gecko, measured by passed test cases, allowing the team’s senior engineers to focus on security, performance and strategic projects. Required qualifications Substantial experience in a browser-engine codebase or in automating for a browser-engine, ideally Firefox/Gecko. Solid Javascript and applying that language skill to write automated tests. Proficiency in and experience developing software in C++. Strong debugging skills in a mature larget codebase. Comfort working in the open: public bugs, code review, and upstream landing. Preferred Prior contributions to Gecko or another major browser engine. Familiarity with web standards and Web Platform Tests.

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