ApplySarthiSenior Contract Web Developer - Firefox (Browser Engine)
Mozilla
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Preparing for this interview
Interviews for contract roles keep coming back to Stakeholder management, Excel, Supply chain. Practise those questions before you sit with Mozilla.
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.
- How do you manage state in a front-end app, and when does it get messy?
- Tell me about a UI you built that users struggled with. What did you change?
- How do you make a page accessible and work on every screen size?
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Practise the Senior Contract Web Developer - 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.