ApplySarthiSenior Contract C++ / JavaScript Software Engineer Firefox (Browser Engine)
Mozilla
Mozilla is also hiring for this role in Remote France, Remote UK.
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Questions you are likely to be asked
- Why do you want to join Mozilla?
- What is your experience with C++? Tell me one thing you learned the hard way.
- What do you do when a production issue happens on your code?
- Walk me through a system you built. How was it designed, and what would you change now?
- Tell me about a hard bug you tracked down. How did you find the cause?
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Practise the Senior Contract C++ / JavaScript Software Engineer Firefox (Browser Engine) at Mozilla interview free →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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Listed on greenhouse · posted 2026-10-20. ApplySarthi collects openings and links to application pages; the role is advertised by Mozilla, not by us.