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Mozilla

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

Remote in set countriesUnited Kingdom onlyContract

Posted 5 days agoConfirmed open 1h ago

Apply on Mozilla's site

Who can apply

United Kingdom only

Salary

Not disclosed

Level

Senior

Contract

Timezone

Not stated

About the role

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.

Skills mentioned

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About Mozilla

All Mozilla remote jobs →Website
Listing details & historyShow
Employer posted
20 Oct 2026
Last confirmed open
1h ago
Source
Employer careers site
Degree
Not mentioned
Visa
Not stated
Timezone
Not stated
Languages
Not stated
Location evidence
“Remote UK”

Details are read from the listing text. They are not a guarantee of work authorization; confirm with the employer.

History

  • 20 Oct · Added to Remotavia
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