Senior AI Model Engineer

Senior AI Model Engineer Join to apply for the Senior AI Model Engineer role at Heidi . Who are Heidi? Heidi is building an AI Care Partner that supports clinicians every step of the way, from documentation to delivery of care. We exist to double healthcare’s capacity while keeping care deeply human. In 18 months, Heidi has returned more than 18 million hours to clinicians and supported over 73 million patient visits. Today, more than two million patient visits each week are powered by Heidi across 116 countries and over 110 languages. Founded by clinicians, Heidi brings together clinicians, engineers, designers, scientists, creatives, and mathematicians, working with a shared purpose: to strengthen the human connection at the heart of healthcare. Backed by nearly $100 million in total funding, Heidi is expanding across the USA, UK, Canada, and Europe, partnering with major health systems including the NHS, Beth Israel Lahey Health, MaineGeneral, and Monash Health, among others. We move quickly where it matters and stay grounded in what’s proven, shaping healthcare’s next era. Ready for the challenge? The Role Working closely with our Engineering Manager, you’ll be a Senior AI Model Engineer on the Model Platform team. You are a technical leader responsible for solving our most critical model-related challenges. Your mission is to drive significant breakthroughs in our model's capabilities, leading research and development efforts in areas like advanced fine-tuning (RLFT), alignment, and reasoning. You will combine your deep ML intuition and research background to push the boundaries of what our models can do. What you’ll do: Lead Model R&D Initiatives: Lead major research and development projects focused on step-changes in model performance, from ideation and experiment design to productionisation. Solve the Hardest Problems: Tackle the most ambiguous and challenging technical problems related to model behaviour, alignment, and safety. Build cutting‑edge fine‑tuned LLMs within Heidi using the latest tools and frameworks. Partner with product, medical knowledge and design teams to automate prompt engineering, build agentic AI, create model evaluation frameworks. Develop Novel Techniques: Go beyond existing literature to develop novel fine‑tuning or data generation techniques tailored to our unique healthcare domain. Mentor and Guide: Mentor mid‑level and junior engineers, sharing your deep expertise and fostering a culture of scientific rigor and innovation. What we will look for: You’ve a proven track record of leading research or development projects that have resulted in significant improvements to large‑scale AI models. You’ve previous hands‑on experience building scalable AI products or features. You’ve shipped AI and LLM‑powered features to real users in a production environment. You are considered an expert in Python, deep learning frameworks (PyTorch/TensorFlow), and the underlying theory of transformer architectures. You have a world‑class intuition for AI/ML, built on a deep and solid foundation in mathematics and statistics. You have the ability to translate vague product needs into concrete research questions and well‑designed experiments. A PhD in Computer Science, AI, Statistics, or a related field is highly preferred. Bonus: A strong publication record in top‑tier AI conferences. Experience building and leading a research‑focused team. Expertise in reinforcement learning or data‑centric AI. What do we believe in? Heidi builds for the future of healthcare, not just the next quarter, and our goals are ambitious because the world’s health demands it. We believe in progress built through precision, pace, and ownership. Live Forever — Every release moves care forward: measured, safe, and built to last. Data guides us, but patients define the truth that matters. Practice Ownership — Decisions follow logic and proof, not hierarchy. Exceptional care demands exceptional standards in our work, our thinking, and our character. Small Cuts Heal Faster — Stability earns trust, speed delivers impact. Progress is about learning fast without breaking what people depend on. Make others better — Feedback is direct, kindness is constant, and excellence lifts everyone. Our success is measured by collective growth, not individual output. Our mission is clear: expand the world’s capacity to care, and do it without losing the humanity that makes care worth delivering. Why you will flourish with us