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Engineering & Development
Full-time
September 22, 2026

Contract Software Engineer - DOM Core Firefox/Gecko

๐ŸŒ Remote France, Remote Germany, Remote UKโฐ Full-time๐Ÿ“… Apply by March 22, 2027
๐Ÿ’ป Engineering & DevelopmentFull-time
Mozilla ยท Direct from employer
Remote France, Remote Germany, Remote UK
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Mozilla is hiring a

Contract Software Engineer - DOM Core Firefox/Gecko

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 teamโ€™s senior engineers to focus on security, performance and strategic projects.

Requirements

  • 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.
Apply for this job

You will be sent to the employer's application page.

Questions about this role

Where can I work from for this Contract Software Engineer - DOM Core Firefox/Gecko role?

Mozilla lists the location as "Remote France, Remote Germany, Remote UK". If your country is not named, check the job description for eligibility rules before applying.

Is this a fully remote job?

Yes. Every role on Euro Remote Talent is remote. This one is full-time, for candidates based in France, Remote Germany, Remote UK.

What does this role pay?

Mozilla has not published a salary for this role. Ask about the range in your first conversation; our salary calculator helps you set expectations.

How do I apply to Mozilla?

Click Apply now. Create an account if you don't have one, or log in to your account, then apply to the job. Applications close on March 22, 2027.

Mozilla

Software, Technology, Internet

Apply now

About Mozilla

Mozilla develops products such as Firefox browsers, Mozilla VPN, and Thunderbird, and works to improve the internet experience for users.

๐Ÿ‘ฅ Size
1001-5000 employees
๐Ÿ“… Founded
2005
๐Ÿญ Industry
Software, Technology, Internet
All jobs at Mozilla โ†’
Job summary
  • TypeFull-time
  • LocationRemote France, Remote Germany, Remote UK
  • CategoryEngineering & Development
  • PostedSeptember 22, 2026
  • DeadlineMarch 22, 2027
About the company

Mozilla develops products such as Firefox browsers, Mozilla VPN, and Thunderbird, and works to improve the internet experience for users.

Mozilla

Contract Software Engineer - DOM Core Firefox/Gecko

Apply now
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September 22, 2026
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