Contract Software Engineer - DOM Core Firefox/Gecko
This is the employer's own posting, not a copy on a job board.
What we know
Is it still open?
Confirmed still open
Last checked 1d ago — checked against the employer's own applicant tracking system, which is the company answering directly.
We re-read the employer's own applicant tracking system and the posting was still there. That is the company answering directly.
How old is it?
Posted 9d ago
The date the source published, not the day we noticed it (2026-09-22). Last seen at its source just now.
We have tracked this listing since 22 Sep 2026 (9 days). The employer's own board has carried it every time we have read it, most recently just now.
Is it remote?
Remote France; Remote Germany; Remote UK
That is the location the employer filed this posting under. Quoted as written — we do not re-word the source's own location.
Who may apply?
France, Germany, United Kingdom
The description states no restriction of its own. This is the source's own tag.
Pay not stated
Similar roles pay €70k–98.8k/yr
Middle 50% of 11 listings that do state pay — Engineering · all levels · France · EUR/year. This employer has published no salary; this is what comparable listings we hold disclose, never converted between currencies or periods. How this is calculated.
Skills named in the ad
Recognised terms only, from a fixed vocabulary — this is what CV matching compares against.
Carried by 1 source
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greenhouse employer's own board first seen 9d ago · last seen just now
The listing
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.