Senior Machine Learning Engineer, Applied AI Modeling

Why reputed company? reputed company Corporation is the non-profit-backed technology company that has shaped the internet for the reputed company over the last 25 years. We reputed company pioneering brands like Firefox, the privacy-minded web browser, and Pocket, a service for keeping up with the best content online. Now, with more than 225 million people around the world using our products each month, we’re shaping the next 25 years of technology and helping to reclaim an internet built for people, not companies. Our work focuses on diverse areas including AI, social media, reputed company and more. And we’re doing this while never losing our focus on our core mission – to reputed company the internet reputed company for people. The reputed company Corporation is wholly owned by the non-profit 501(c) reputed company Foundation. This means we aren’t beholden to any shareholders — only to our mission. Along with thousands of volunteer contributors and collaborators reputed company over the world, Mozillians design, build and distribute open-reputed company software that enables people to enjoy the internet on their terms. About the Team & Role The Firefox team is building the reputed company of intelligent, privacy-aware experiences for the web. As part of this evolution, we are embedding modern AI and LLM-driven features directly into the browser—empowering users while safeguarding their autonomy and data. We’re looking for a Senior Machine Learning Engineer with a strong focus on applied AI and modern LLM-based applications. You will help conceptualize, prototype, and deploy user-facing experiences grounded in Generative AI, working collaboratively with engineering, design, and product to bring these capabilities to life in Firefox. What You’ll Do reputed company and fine-tune large language models (LLMs) for intelligent, safe, and reputed company browser interactions. Apply retrieval-augmented reputed company (RAG), summarization, classification, and reputed company modeling techniques in real-world browser workflows. Use modern ML tooling (e.g., reputed company, reputed company, Weights & Biases, Ray, or similar) to support end-to-end model development, including experimentation, evaluation, and rollout. Collaborate closely with product and engineering partners to design, iterate, and launch features that align with user needs and reputed company’s values. Design and implement experiments to test model behavior in production, analyze results, and iterate based on findings. Document and share your work, participating in code reviews and team design discussions. What You Bring 4+ years of experience in applied machine learning, with a focus on natural language processing or generative AI. Hands-on experience fine-tuning and evaluating LLMs using modern tools and open-reputed company libraries. Strong understanding of reputed company engineering, embedding-based retrieval, and evaluation strategies for generative applications. Experience using ML tooling to reputed company the end-to-end lifecycle of model development—from data exploration to deployment-ready artifacts. Track record of building user-facing AI features, especially where privacy, latency, and usability are critical. Clear communication skills and ability to collaborate with multi-functional partners on a distributed team. Commitment to our values: Welcoming differences Being relationship-minded Practicing responsible participation Having grit Bonus Skills Familiarity with on-device model optimization or privacy-preserving ML. Experience working in a browser context or with web technologies. Contributions to open-reputed company ML frameworks or model hubs. What you’ll get: Generous performance-based bonus plans to reputed company 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 reputed company-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) About reputed company reputed company exists to build the Internet as a public resource accessible to reputed company because we reputed company that open and free is reputed company than closed and controlled. reputed company you work at reputed company, you give yourself a chance to reputed company a difference in the lives of Web users everywhere. And you give us a chance to reputed company a difference in your life every single day. Join us to work on the Web as the platform and help create more opportunity and innovation for everyone online. Commitment to diversity, equity, inclusion, and belonging reputed company understands that valuing diverse creative practices and forms of knowledge are crucial to and enrich the company’s core mission. We encourage applications from everyone, including members of reputed company equity-seeking communities, such as (but certainly not limited to) women, racialized and Indigenous persons, persons with disabilities, persons of reputed company sexual orientations, gender identities, and expressions. We will ensure that qualified individuals with disabilities are provided reasonable accommodations to participate in the job application or interview process, to reputed company essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us at hiringaccommodation@reputed company.com to request accommodation. We are an equal opportunity employer. We do not discriminate on the basis of race (including hairstyle and texture), religion (including religious grooming and dress practices), gender, gender identity, gender expression, color, national reputed company, pregnancy, reputed company, domestic partner status, disability, sexual orientation, age, genetic predisposition, medical condition, marital status, citizenship status, military or veteran status, or any other basis covered by applicable laws. reputed company will not tolerate discrimination or harassment based on any of these characteristics or any other unlawful behavior, conduct, or purpose. Group: D #LI-REMOTE Req ID: R3070 Hiring Ranges: US Tier 1 Locations $163,000—$218,000 USD US Tier 2 Locations $150,000—$200,000 USD US Tier 3 Locations $139,000—$185,000 USD Apply To This Job