Principal Machine Learning Engineer - Applied AI & LLMs (x/f/m)

What you’ll do We are looking for a Principal Machine Learning Engineer to join the DS & AI organization at Doctolib. This is a transversal force multiplier role operating across all AI teams: Clinical, Productivity, Phone Assistant and ASR. Rather than working within a single feature team, you will own the cross-cutting technical challenges: defining how Doctolib's product and AI teams build agentic solutions, standardizing ML evaluation frameworks, and spreading strong engineering practices across the org. You will unblock teams, shape architecture decisions, and take on the deep technical work that requires senior ML judgment at scale, directly impacting the daily lives of 400,000 healthcare professionals and the health of 80 million patients. Building at Doctolib means delivering innovative products that measurably improve outcomes for care teams and patients alike. Technical Strategy & Architecture Own cross-team ML architecture decisions, from model selection to production deployment patterns and strategic build vs. buy decisions Define and drive adoption of rigorous evaluation frameworks across all AI teams, setting the standard for how Doctolib measures model and agentic performance Establish shared production infrastructure patterns for AI: model and prompt versioning, guardrails, uncertainty quantification, cost optimization, and observability Lead the technical design of agentic solutions and define how product teams across Doctolib build on top of AI capabilities Elevate technical standards across the DS & AI org by influencing Staff and Senior ML Engineers through architecture reviews, technical guidance, and practice propagation Partner with Product, Legal, and Compliance teams to ensure safe rollout and meet EU regulatory expectations (GDPR, MDR, EU AI Act) Who you are Before you read on, if you don't have the exact profile described below, but you feel this job description matches your skill set, we still encourage you to apply. You'll be a great fit if: You have 10+ years in ML/AI with 3+ years at Staff+ or Principal level leading complex, multi-team technical initiatives You have deep expertise in at least two of: clinical NLP, LLM fine-tuning and evaluation, automatic speech recognition, RAG systems, or reinforcement learning You are expert in Python, PyTorch/Transformers for training, and vLLM for inference with a track record deploying ML systems in production (AWS/GCP) You have a PhD in Computer Science, AI, Statistics, or related field (or equivalent research experience) You have exceptional communication skills and are able to align diverse stakeholders and explain complex technical decisions Now it would be fantastic if you have: Publications in top-tier ML/AI conferences (NeurIPS, ICLR, ACL) or medical informatics venues Experience with EU healthcare regulations (GDPR, MDR, AI Act) Prior work with clinical data or healthcare applications Life at Doctolib Tech Our solutions are built on a single fully cloud-native platform supporting web and mobile interfaces across multiple languages and healthcare specialties. Our stack includes Rails, TypeScript, Java, Python, Kotlin, Swift, and React Native. We leverage AI ethically to empower patients and professionals. Discover our AI vision here . Want to learn more about our tech culture and environment? Visit the Doctolib Tech site . What we offer A Deutschlandticket (Germany-wide public transport pass) fully paid for by Doctolib 28 vacation days + 1 additional day for each full calendar year of employment (up to a maximum of 30 days) Work from abroad for up to 10 days per year thanks to our flexibility days policy Company health insurance with great supplementary benefits through our partner Allianz Company pension scheme (bAV) through Allianz with an employer subsidy of 40% (15% within the probationary period) The Doctolib Parent Care program, which include