Mozilla
Senior Contract C++ / JavaScript Software Engineer Firefox (Browser Engine)
- Location
- Remote UK
- Work model
- Remote
- Seniority
- Senior
- Employment
- Contract
- Posted
- Added to Codestelle
Work location
The listing states a work-location scope.
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Listing locationRemote UK
Extracted 2026-10-20 · Automated text analysis, not employer confirmation.
Original job listing ↗Language requirements
- German
- Not specified
- English alone
- Not specified
Based on explicit wording in the listing. “Not specified” does not mean a language is optional.
About this 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.