AI Research Scientist (Europe/UK - Remote)

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. AI Proficiency at Sword Health AI fluency is a core expectation at Sword Health. Every candidate is assessed against our three-level framework — be ready to share real examples of how AI is already part of how you work. Explorer (Level 1) — Uses AI daily to boost personal productivity Builder (Level 2) — Creates workflows and tools that elevate the whole team Integrator (Level 3) — Embeds AI into products and processes at scale Every hire must demonstrate at least Level 1. The expected level will vary depending on the seniority of the role. 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); Deep expertise in one or more of: large language models, reinforcement learning from human feedback, multimodal learning (vision, speech), or agentic AI systems; Experience building or contributing to LLM-based agents, including prompt engineering, memory orchestration, or agentic workflows; A track record of taking research ideas from conception to working systems, including developing and debugging complex ML pipelines; Industry experience during or after the PhD (e.g., research internships at leading AI labs); Comfort with ambiguity and a track record of delivering results in fast-moving, high-uncertainty environments where research and product development happen in parallel; Strong communication skills and a history of effective cross-functional collaboration; A broader record of research excellence demonstrated through grants, fellowships, patents, or impactful open-source contributions. *This range includes base, variable and equity These compensation bands are just the starting point. Once someone joins and proves they’re outlier talent, we adjust quickly to ensure their compensation aligns with their impact. Our job titles may span more than one career level. Actual pay is determined by skills, qualifications, experience, location, market demand, and other factors. Compensation details listed in this posting reflect the base salary and any potential variable, bonus or sales incentives, and the Company’s estimation of the value of private company stock options, if applicable. The pay range is subject to change, future value of company stock options is not guaranteed, and compensation may be modified in the future. In addition to our total compensation, Sword offers a number of benefits as listed below. Portugal - Sword Benefits & Perks: • Health, dental and vision insurance • Meal allowance • Equity shares • Remote work allowance • Flexible working hours • Work from home • Discretionary vacation • Snacks and beverages Note: Please note that this position does not offer relocation assistance. Candidates must possess a valid EU visa and be based in Portugal. Sword Health complies with applicable Federal and State civil rights laws and does not discriminate on the basis of Age, Ancestry, Color, Citizenship, Gender, Gender expression, Gender identity, Gender information, Marital status, Medical condition, National origin, Physical or mental disability, Pregnancy, Race, Religion, Caste, Sexual orientation, and Veteran status.