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

What you’ll doWe 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 & ArchitectureOwn cross-team ML architecture decisions, from model selection to production deployment patterns and strategic build vs. buy decisionsDefine and drive adoption of rigorous evaluation frameworks across all AI teams, setting the standard for how Doctolib measures model and agentic performanceEstablish shared production infrastructure patterns for AI: model and prompt versioning, guardrails, uncertainty quantification, cost optimization, and observabilityLead the technical design of agentic solutions and define how product teams across Doctolib build on top of AI capabilitiesElevate technical standards across the DS & AI org by influencing Staff and Senior ML Engineers through architecture reviews, technical guidance, and practice propagationPartner with Product, Legal, and Compliance teams to ensure safe rollout and meet EU regulatory expectations (GDPR, MDR, EU AI Act)Who you areBefore 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 initiativesYou have deep expertise in at least two of: clinical NLP, LLM fine-tuning and evaluation, automatic speech recognition, RAG systems, or reinforcement learningYou 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 decisionsNow it would be fantastic if you have:Publications in top-tier ML/AI conferences (NeurIPS, ICLR, ACL) or medical informatics venuesExperience with EU healthcare regulations (GDPR, MDR, AI Act)Prior work with clinical data or healthcare applicationsLife at Doctolib TechOur 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 offerFree comprehensive health insurance for you and your children25 days of paid vacation per year, plus up to 14 days of RTTFree mental health and coaching services through our partner Moka.careWork from abroad for up to 10 days per year thanks to our flexibility days policyLunch vouchers with Swile card (8.50 value, 4.50 covered by Doctolib)Work Council subsidy for sports club memberships or creative classes50% reimbursement of your public transport subscriptionParent Care Program: one additional month of leave on top of legal parental leaveFor caregivers and workers with disabilities: remote policy adaptation, extra medical leave, and psychological supportRelocation support for international mobilityAccess to premium AI tools for development and dedicated trainingThe interview processHR ScreenHiring Manager InterviewTechnical InterviewTechnical Case StudyBehavioral InterviewAt least one reference checkWe want your experience to be clear, respectful, and transparent. Learn more on our candidate experience page.Job detailsPermanent positionFull-timeParis, FranceHybrid work mode (up to 2 remote days per week)Start date: as soon as possibleWe welcome everyoneAt Doctolib, we believe in improving access to healthcare for everyone - regardless of where you come from or what you look like. We evaluate candidates based solely on qualifications and motivation, without any form of discrimination. We respect and celebrate diversity!The more diverse ideas are heard, the more our product will truly improve healthcare for all. You are welcome to apply regardless of gender, religion, age, sexual orientation, ethnicity, disability, or place of origin.To ensure equal opportunities, we invite you to exclude personal information (e.g., pictures, age) from your applications. If you have a disability, let us know if there's any way we can make the interview process smoother for you! Join us in building the healthcare we all dream of.Your data privacyAll information transmitted via this form is processed by Doctolib for application management. For more on how we process your data, click here. For inquiries or to exercise your rights, contact us at hr.dataprivacy(at)doctolib.com.