Mozilla
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500 - 10000 Employees
Contract Software Engineer - DOM Core Firefox/Gecko
Location not specified
Posted on Sep 22, 2026
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.
About Mozilla
A lot of companies say they’re “mission-driven.” Our unique corporate structure guarantees that every decision we make upholds our mission: to ensure the internet remains open and accessible. Beholden to neither shareholders nor investors, Mozilla Corporation is wholly owned by the not-for-profit Mozilla Foundation.
Along with our communities of 20,000+ contributors and collaborators, Mozilla Corporation’s staff designs, builds, and distributes software that allows people to enjoy the internet...
Job overview
Employment type
Contract
Experience level
Mid Level
Work type
Remote
Department
Firefox
Posted
on Sep 22, 2026
Financials
Type
private
Annual Revenue
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Market Cap
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Amount Raised
23m+
Membership
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