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

Mozilla
On-site
Posted about 18 hours ago
QA & Testing

AI summary

You will enhance the Firefox DOM Core team by improving test coverage and fixing issues related to Session History, focusing on writing Web-Platform tests and debugging in the Gecko codebase.

Eligible from: Unclear

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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About the job

Posted on
Oct 21, 2026
Job type
Contract
Location
GermanyOn-site

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