Mozilla: Senior Software Engineer (Localization)

Headquarters: California
URL: https://www.mozilla.org/en-US/

About this team and role:

The Localization Team manages the infrastructure that powers localization across all Mozilla products and services, and supports our global community of volunteer localizers. As a Senior Engineer, you’ll contribute to a range of Mozilla localization projects and technologies — from Pontoon, our Django-based Translation Management System, to open source libraries like moz-l10n. You’ll also engage with development of standards such as Unicode MessageFormat and work on internationalization features that shape the experience of Firefox and other Mozilla products.

You’ll contribute to architectural discussions and help drive feature development within the team. At Mozilla, Senior Engineers are expected to work independently on well-defined projects, collaborate closely with peers, and play a key role in delivering high-quality software that advances the team’s goals and Mozilla’s mission.

What you’ll do: 

• Contribute to the development of Python and JavaScript libraries (such as moz-l10n) and tools that support Mozilla’s localization infrastructure.
• Collaborate with engineers and program managers to design and implement new Pontoon features, across both the front-end and back-end.
• Improve internationalization within the Firefox codebase to make features more adaptable and accessible across languages and regions.
• Contribute to discussions shaping Mozilla’s positions on internationalization and localization standards.
• Engage with our community of volunteer developers and localizers to support and guide Mozilla’s localization efforts.
• Collaborate effectively with teammates and internal clients across regions and time zones.

What you’ll bring: 

• Strong experience developing and maintaining web applications and tools using Python and JavaScript.
• Solid understanding of web technologies, APIs, and modern development workflows.
• Experience with internationalization (i18n) and localization (l10n) concepts, tools, or workflows.
• Ability to collaborate effectively in a distributed team, across time zones and disciplines.
• Excellent communication skills, with an emphasis on clarity and working across technical and non-technical roles.
• Commitment to our values:
• Welcoming differences
• Being relationship-minded
• Practicing responsible participation
• Having grit

Bonus points:

• Fluency in another language and understanding of linguistic diversity (e.g., grammar, plurals, text direction, and cultural conventions).
• Experience with open source development practices and community collaboration.
• Programming experience in Rust and C++.

What you’ll get:

• Generous performance-based bonus plans to all eligible employees - we share in our success as one team
• Rich medical, dental, and vision coverage
• Generous retirement contributions with 100% immediate vesting (regardless of whether you contribute)
• Quarterly all-company wellness days where everyone takes a pause together
• Country specific holidays plus a day off for your birthday
• One-time home office stipend
• Annual professional development budget
• Quarterly well-being stipend
• Considerable paid parental leave
• Employee referral bonus program
• Other benefits (life/AD&D, disability, EAP, etc. - varies by country)

To apply: