ApplySarthiSenior Contract C++ / JavaScript Software Engineer Firefox (Browser Engine)
Mozilla
Tailor my CV for this job, freeView job and applyYour CV rewritten for this role, from your real experience. Sign in with Google, nothing to install.
Got this interview? Our apps help you get the job.
Skills named in this job
Read from the description itself, not inferred.
This role on the market
34 open javascript roles across 15 companies are on ApplySarthi right now, most of them in Bengaluru (4), Pune (1), Mumbai (1).
- Front-End Engineer 4 (JavaScript, TypeScript, Angular)Capitalone
- Senior Javascript Support Engineer-Support (SuiteCloud) - Q2FY27Oracle
- JavaScript developer (React)Veeam Software
- Senior Application Engineer (Python/JavaScript/Typescript)Jobgether
- Software Engineer II (Java, Android/Kotlin/IOS/Javascript)Motorolasolutions · bengaluru
What javascript roles keep asking for: JavaScript (71%), AWS (35%), CI/CD (35%), Kubernetes (35%), React (35%), TypeScript (35%), Agile (32%), Docker (32%) — counted across their open postings here.
Mozilla has 104 open roles listed here.
- Contract Staff Software Engineer-Bug Burndown
- Contract Staff Software Engineer-Bug Burndown
- Contract Staff Software Engineer - (Firefox) C++,Storage Encryption
- Senior Contract C++ / JavaScript Software Engineer Firefox (Browser Engine)
- Senior Contract C++ / JavaScript Software Engineer Firefox (Browser Engine)
Counted across 14 company job boards, updated as roles open and close.
Preparing for this interview
Interviews for javascript roles keep coming back to JavaScript, AWS, CI/CD, Kubernetes. 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 decide what to test, and what does good code review look like to you?
- Describe a time a deadline forced a trade-off in quality. What did you choose and why?
- How would you design an API for a feature you have worked on?
Prep Sarthi gives you a free mock interview: an AI interviewer asks you questions like these out loud, from your own CV and this job, and shows your score and your weakest answer.
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.
Match this job to your CV
ApplySarthi scores your CV against this role, shows the skills you are missing, and writes a tailored version for the application.
Check my match →Similar open roles
Need answers during your interview? Try Live Sarthi.
Live Sarthi, an Interview Sarthi app, shows answer suggestions during the call.
- Hidden from supported screen sharingThe overlay stays out of supported Windows screen captures.
- Answers start in about 1.5 secondsResponse time varies with your connection and model.
- From your own CVYour projects and your experience, not a generic script.
- 30 minutes freeThen ₹99 for a 2-day pass with unlimited calls — you pay for the days you are interviewing, not a subscription.
A Windows app, from the same team as ApplySarthi.
Listed on greenhouse · posted 2026-10-20. ApplySarthi collects openings and links to application pages; the role is advertised by Mozilla, not by us.