[Remote] Senior Machine Learning Engineer, Applied AI Modeling

Note: The job is a remote job and is open to candidates in USA. Mozilla Corporation is a non-profit-backed technology company known for shaping the internet positively over the past 25 years. They are seeking a Senior Machine Learning Engineer to develop and fine-tune large language models for intelligent browser interactions, collaborating with various teams to enhance user experiences in Firefox.ResponsibilitiesDevelop and fine-tune large language models (LLMs) for intelligent, safe, and responsive browser interactionsApply retrieval-augmented generation (RAG), summarization, classification, and intent modeling techniques in real-world browser workflowsUse modern ML tooling (e.g., Hugging Face, LangChain, Weights & Biases, Ray, or similar) to support end-to-end model development, including experimentation, evaluation, and rolloutCollaborate closely with product and engineering partners to design, iterate, and launch features that align with user needs and Mozilla’s valuesDesign and implement experiments to test model behavior in production, analyze results, and iterate based on findingsDocument and share your work, participating in code reviews and team design discussionsSkills4+ years of experience in applied machine learning, with a focus on natural language processing or generative AIHands-on experience fine-tuning and evaluating LLMs using modern tools and open-source librariesStrong understanding of prompt engineering, embedding-based retrieval, and evaluation strategies for generative applicationsExperience using ML tooling to lead the end-to-end lifecycle of model development—from data exploration to deployment-ready artifactsTrack record of building user-facing AI features, especially where privacy, latency, and usability are criticalClear communication skills and ability to collaborate with multi-functional partners on a distributed teamCommitment to our values: Welcoming differences, Being relationship-minded, Practicing responsible participation, Having gritFamiliarity with on-device model optimization or privacy-preserving MLExperience working in a browser context or with web technologiesContributions to open-source ML frameworks or model hubsBenefitsGenerous performance-based bonus plans to all eligible employees - we share in our success as one teamRich medical, dental, and vision coverageGenerous retirement contributions with 100% immediate vesting (regardless of whether you contribute)Quarterly all-company wellness days where everyone takes a pause togetherCountry specific holidays plus a day off for your birthdayOne-time home office stipendAnnual professional development budgetQuarterly well-being stipendConsiderable paid parental leaveEmployee referral bonus programOther benefits (life/AD&D, disability, EAP, etc. - varies by country)Company OverviewMozilla provides internet solutions and offers firefox, thunderbird, and raindrop. It was founded in 1998, and is headquartered in Mountain View, California, USA, with a workforce of 501-1000 employees. Its website is https://www.mozilla.org.Company H1B SponsorshipMozilla has a track record of offering H1B sponsorships, with 2 in 2025, 5 in 2024, 4 in 2023, 3 in 2022, 2 in 2021, 6 in 2020. Please note that this does not guarantee sponsorship for this specific role.