AI Research Scientist - Sword Health

At Sword, we’re building AI to heal billions and unlock humanity’s full potential. In doing so, we’re pioneering AI Care, a fundamentally new approach to healthcare built for medical reasoning, safety, and real-time treatment, not generic technology applied after the fact. As both a clinical-centric frontier AI lab and an applied AI platform, Sword is reimagining how care is delivered at scale, removing traditional barriers like appointments, waiting rooms, and stigma so more people can access the care they need—and ultimately get back to lives lived in full. Since 2020, Sword has expanded across physical therapy, women’s health, cardiometabolic, and mental health, and is now moving beyond the session to a fully AI-native, 24/7 care program that brings physical activity, therapeutic exercise, psychotherapy, nutrition, and behavior change into one connected experience. More than 700,000 members across three continents have completed over 10 million AI sessions, helping 1,000+ enterprise clients avoid more than $1 billion in unnecessary healthcare costs. Backed by 42 clinical studies, 44+ patents, and more than $500 million raised from leading investors including Khosla Ventures, General Catalyst, and Founders Fund, Sword is defining a new standard for healthcare.

What you'll be doing:

• Design and execute research on LLM fine-tuning, alignment, and post-training methods (SFT, RLHF) tailored for clinical and therapeutic domains;
• Develop and improve foundational AI models that power our AI agents, spanning language, vision, speech, and multimodal systems;
• Contribute to the full model development cycle: dataset curation and annotation, architecture design, training, evaluation, and iteration;
• Collaborate across AI Engineering, Product, and Clinical teams to translate research breakthroughs into production systems that deliver patient care;
• Work towards long-term ambitious research goals, such as clinical memory, long-horizon planning, and safety validation, while identifying and delivering immediate milestones;
• Advance the field by publishing in top-tier AI venues and clinical journals, contributing to Sword's growing body of peer-reviewed research.

What you need to have:

• A PhD in Computer Science, Machine Learning, Natural Language Processing, or a closely related AI field;
• Hands-on experience fine-tuning large language models (pre-training, SFT, RLHF, or related post-training techniques);
• A strong publication track record in peer-reviewed AI conferences or journals;
• Proficiency in Python and deep experience with modern ML frameworks (e.g., PyTorch, JAX);
• Demonstrated ability to design rigorous experiments and interpret their results.

What we would love to see:

• First-author publications in top-tier AI conferences (e.g., NeurIPS, ICML, ICLR, ACL, EMNLP, COLM, CVPR);<