Research Scientist - Environments, Data and Post-Training

About Mercor Mercor’s mission is to organize human intelligence for the AI economy. We build the infrastructure that enables frontier AI labs and enterprises to train, evaluate, and improve AI on real-world professional work. More than five million experts have joined our network, and we pay out over $5 million daily for their knowledge and expertise. We built our training and evaluation infrastructure alongside the world’s leading AI labs. Now, we’re bringing those capabilities to enterprises across industries, enabling them to train, evaluate, and improve AI using their own expertise and standards. Our APEX benchmarks measure how AI performs on economically valuable work, while our enterprise evaluations and post-training capabilities turn those insights into measurable improvements across real-world workflows. Our work sits at the intersection of frontier AI, human expertise, and real-world application. We’re solving problems few companies have encountered, with the opportunity to influence what the world’s most advanced AI systems become capable of doing. We’re looking for people who bring different perspectives, take ownership, exercise sound judgment, and hold themselves to an exceptionally high standard. You’ll have the opportunity to do consequential work alongside talented colleagues who challenge one another, collaborate openly, and share a commitment to excellence. Mercor is profitable and recently raised a $750 million Series D at a $20 billion valuation. We work in person five days a week in San Francisco, New York, and London. About the Role As a Research Scientist at Mercor, you will work at the intersection of research and engineering on frontier post-training. You will develop new training and evaluation methods, test them through rigorous experiments, and implement successful approaches at scale. Working with researchers, engineers, domain experts, and customers, you will investigate how data, rewards, environments, and optimization methods shape model behavior. Your work will influence frontier models, Mercor’s products, and the broader research community through releasing blogposts, technical reports, and papers. What You’ll Do Implement novel post-training methods that improve model reasoning, tool use, and agentic behavior. Develop new training recipes for frontier open models. Design and run experiments across datasets, reward functions, environments, and optimization strategies, including methods such as GRPO and DAPO. Build reinforcement learning with verifiable rewards (RLVR) and other post-training pipelines at scale. Investigate model capabilities and failure modes, then develop targeted training interventions. Create methods for measuring data quality, usability, and causal impact on model performance. Build scalable pipelines for data generation, filtering, augmentation, and selection. Develop rubrics, evaluators, benchmarks, and scoring systems that inform training decisions. Translate open-ended research questions into rigorous experiments and production systems. Collaborate with researchers, applied AI teams, engineers, and domain experts producing training data. Contribute to open-source post-training tools and research. What We’re Looking For Demonstrated experience training and evaluating machine learning models. A strong research record in post-training, reinforcement learning, language-model evaluation, data-centric ML, or a closely related field. Ability to reason rigorously about model behavior, experimental results, and data quality. Strong programming skills and experience implementing machine learning systems. Knowledge of the current AI research landscape and important open problems. Excitement to work in person in San Francisco, five days a week (with optional remote Saturdays), and thrive in a high-intensity, high-ownership environment. Nice To Have Experience on an industry post-training or frontier-model team. Main authorship of publications at top-tier conferences (NeurIPS, ICML, ACL). Experience with synthetic-data generation Experience building large-scale evaluation or data-generation infrastructure. Solid foundations in distributed or backend systems, and experimental design. Familiarity with APIs, databases, and cloud infrastructure. Benefits: Generous equity grant vested over 4 years Health, dental, and vision insurance 401(k) with company match Unlimited paid vacation and sick days Parental leave for birthing and non-birthing parents Free mental health services $200 monthly wellness reimbursement $1.5K monthly meal stipend $200 monthly laundry reimbursement Free Equinox membership Up to $15K relocation bonus Mercor is an Equal Opportunity Employer and is committed to providing equal opportunity to all employees and applicants. Mercor does not discriminate based on actual or perceived race, color, creed, religion, national origin, ancestry, citizenship status, age, sex or gender (including pregnancy, childbirth, related medical conditions and lactation), gender identity or gender expression, sexual orientation, marital status, military service and veteran status, disability, protected medical condition as defined by California or local law, genetic information, or any other characteristic protected by applicable federal, California, or local laws and ordinances. Further, Mercor prohibits discrimination, harassment, and retaliation based on any combination of protected characteristics. This Policy applies to all areas of employment, including recruitment, hiring, training, promotion, compensation, benefits, discipline, termination, and all other privileges, terms, and conditions of employment. This Policy and the law prohibit employment discrimination against any employee or applicant based on any legally protected status.