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Senior Contract C++ / JavaScript Software Engineer (Browser Engine)

Mozilla 路 Remote Belgium; Remote Denmark; Remote Finland; Remote France; Remote Netherlands; Remote Poland

Extracted from the posting

Base
Not stated
Remote
Remote
Stack
JavaScript, Gecko, Web Platform Tests, Mocha

Improve Session History test coverage and correctness in Firefox's Gecko DOM Core. Write Web Platform and Gecko tests using JavaScript and C++.

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鈥檚 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.

Technologies

JavaScriptGeckoWeb Platform TestsMocha
Mozilla
Mozilla

Job details

TypeContract
Work ModeRemote
LevelMid Level
LocationRemote Belgium; Remote Denmark; Remote Finland; Remote France; Remote Netherlands; Remote Poland
PostedSep 22, 2026
Apply Now

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