Contract Software Engineer - DOM Core Firefox/Gecko

mozilla · Job · via Arbeitnow

Type
Job
Organization
mozilla
Location
Remote
Deadline
Rolling or not stated
Who can apply
On-site in Remote
Posted
24 September 2026
Skills mentioned
JavaScript, C++

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About this Opportunity

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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Documents you may need

  • Updated CV / Resume
  • Cover Letter (tailored to this role)
  • English Language Certificate (IELTS/TOEFL)

How to apply

  1. Click the "Apply — via Arbeitnow" button to go to the source page.
  2. Read the full description and confirm you meet the requirements.
  3. Prepare your CV and cover letter tailored to this role.
  4. Submit your application through the official portal.
  5. Follow up within 1–2 weeks if you do not hear back.

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