Senior Applied Machine Learning Engineer - Search & Recommendations

Upwork ($UPWK) is the world’s human and AI-powered work marketplace that connects businesses with highly skilled, AI-enabled independent talent from across the globe. From entrepreneurs to Fortune 100 enterprises, companies rely on Upwork’s trusted platform and its mindful AI companion, Uma, to find and hire expert talent, leverage AI-powered work solutions, and drive business transformation. With on-demand access to professionals spanning more than 10,000 skills across AI & machine learning, software development, sales & marketing, customer support, finance & accounting, and more, Upwork enables businesses of all sizes to scale, innovate, and build agile teams for the age of AI and beyond.

Upwork’s platform has facilitated more than $25 billion in economic opportunity for talent around the world. Learn more at Upwork.com and follow us on LinkedIn, Facebook, Instagram, TikTok, and X.

Are you passionate about using machine learning to drive meaningful change? As a Senior Applied Machine Learning Engineer at Upwork, you will leverage advanced machine learning techniques to deliver cutting-edge solutions that directly impact our global platform and user experience. You’ll work with large-scale data to solve complex problems, from improving search relevance to personalizing recommendations, and create a powerful, seamless experience for our users. This is a unique opportunity to contribute to the innovation at the world’s largest work marketplace, where your work will enable our community of freelancers and clients to connect and collaborate in impactful ways.

• Analyze millions of structured and unstructured data to identify patterns and insights in user behavior and build meaningful features to improve model performance
• Design and implement efficient and reusable features, models and systems for different machine learning applications (classical & deep learned models) in low latency fashion
• Contribute to the performance and continued optimization of our recommendation systems: build machine learning models to improve understanding of user preferences, user intent and context to deliver accurate, relevant and personalized recommendations 
• collaborate with the business, analytics, and engineering counterparts to share the discovered data stories with stats, charts, and formal presentations, and finally propose recommendations to maximize the business impact.
• Build and fine‑tune large language models (LLMs), transformers, agents, and/or hybrid systems to improve relevance, semantic understanding, and user experience.

• Masters/PhD in Computer Science, Machine Learning, NLP, Mathematics, or a related quantitative field (or equivalent research experience).
• 3+ years of relevant industry experience building large scale ML systems  
• Prior experience with large language models, retrieval augmented generation (RAG), or agentic AI.
• Strong experience with Python, SQL PyTorch and/or TensorFlow 
• Clear track record of publications in peer‑reviewed conferences or journals (e.g. ACL, EMNLP, NeurIPS, ICML, ICLR, KDD, SIGIR, WWW etc.).
• Knowledge of distributed training techniques, and efficiency at scale (memory, latency, hardware constraints).

At Upwork, you’ll shape the future of work for a global, remote-first workforce, creating economic opportunities for professionals worldwide. While we have a physical office in Palo Alto, we currently hire full-time employees in 34 U.S. states, making it easier than ever to join our mission from wherever you call home.

Our culture is built on trust, risk-taking, customer focus, and excellence, all in service of our core mission: to create economic opportunities so people have better lives. We embrace authenticity and inclusion, encouraging everyone to bring their whole selves to work. Personal and professional growth is a priority here, supported through development programs, mentorship, and our Upwork Belonging Communities.

We’re proud to offer benefits that go beyond the basics, including comprehensive medical coverage for you and your family, unlimited PTO, a 401(k) plan with matching, 12 weeks of paid parental leave, and an Employee Stock Purchase Plan. Visit our Life at Upwork page to learn more about our values, working principles, and the overall employee experience.

Ready to help shape the future of work? Check out our Careers page to learn more about opportunities at Upwork.

Upwork is an Equal Opportunity Employer committed to recruiting and retaining a diverse and inclusive workforce. We do not discriminate based on race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, or other legally protected characteristics under federal, state, or local law.

Please note that a criminal background check may be required once a conditional job offer is made. Qualified applicants with arrest or conviction records will be considered in accordance with applicable law, including the California Fair Chance Act and local Fair Chance ordinances.