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

MozillaLast month

Where you can work from
Remote — Belgium, Denmark, Finland and 3 moreBelgium, Denmark, Finland, France, Netherlands, Poland
Salary
Salary not disclosedThe employer did not publish a range. We do not estimate one.
Job type
Contract
Experience
Not stated

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Job description

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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Job availability & source

Still listed on the employer's own board at our last check, 2 hours ago

This job was originally posted by the employer or source shown below. We re-check the original listing regularly to keep its availability current, and send you straight to it to apply — we never sit in between.

Source
Mozilla (Greenhouse)
Posted by the employer
22 Sept 2026
First seen by us
22 Sept 2026
Last checked
24 Oct 2026
View the original posting

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