Machine Learning Engineer

About The Company
Doctolib is a leading healthcare technology company dedicated to transforming the way healthcare services are delivered and accessed across Europe. With a focus on innovation and patient-centric solutions, Doctolib provides a comprehensive digital platform that connects healthcare professionals, patients, and healthcare institutions. Our mission is to improve access to quality healthcare by leveraging cutting-edge technology, ensuring safety, efficiency, and trust in medical interactions. We operate on a fully cloud-native infrastructure, supporting web and mobile interfaces across multiple countries and healthcare specialties. Our commitment to ethical AI use and continuous technological advancement positions us as a pioneer in digital health solutions.

About The Role
We are seeking a highly skilled Staff Machine Learning Engineer - Retrieval to join our AI team. In this pivotal role, you will be instrumental in developing and maintaining Doctolib's Medical Knowledge Platform, a core component that ensures clinical AI decisions are grounded in validated, trusted medical sources such as HAS guidelines, learned society recommendations, and peer-reviewed clinical studies. Your expertise will directly impact the safety and reliability of AI-powered healthcare experiences used by hundreds of thousands of health professionals and millions of patients across Europe. You will work on designing scalable retrieval systems capable of handling vast document repositories, optimizing query processing pipelines, and building custom re-ranking solutions to enhance retrieval accuracy. This role offers an exciting opportunity to shape the future of healthcare AI, working with a talented team committed to innovation and excellence.

Qualifications

• Proven experience in building and scaling search and retrieval systems in high-traffic, production environments
• Deep expertise in both offline indexing and online retrieval pipelines
• Hands-on experience with retrieval technologies such as Elasticsearch, Solr, Vertex AI, vector search, embeddings, and re-ranking techniques
• Strong programming skills in Python, Java, or related languages
• Experience designing and operating systems capable of handling over 100 million documents with sub-300ms latency
• Ability to develop custom re-rankers and optimize query processing pipelines
• Experience with deep Retrieval-Augmented Generation (RAG) systems beyond off-the-shelf components
• Autonomous with the ability to work at senior or staff levels, demonstrating technical depth and ownership
• Familiarity with medical knowledge sources, clinical databases, or healthcare information systems (preferred)
• Experience contributing to evaluation frameworks and benchmarks for retrieval quality or AI outputs in regulated environments (preferred)
• Knowledge of multilingual retrieval contexts or domain-specific ontologies (preferred)

Responsibilities

• Build and own Doctolib's Medical Knowledge Platform, ensuring it effectively grounds clinical AI decisions in validated medical sources
• Design, develop, and maintain indexing pipelines and retrieval systems with end-to-end ownership
• Architect scalable systems capable of managing large document repositories and high request volumes
• Optimize retrieval pipelines for speed and accuracy, ensuring sub-300ms response times
• Develop custom re-rankers and query expansion techniques to improve retrieval relevance
• Engineer deep RAG systems, going beyond conventional solutions to address complex medical knowledge challenges
• Implement and improve vector search, embeddings, re-ranking, and query rewriting components across the full retrieval stack
• Collaborate with cross-functional teams to integrate retrieval systems into clinical decision support tools
• Continuously evaluate and refine retrieval performance using robust benchmarks and metrics

Benefits

• Comprehensive health insurance coverage for employees and their children
• 25 days of paid vacation annually, plus up to 14 days of RTT
• Free mental health and coaching services through Moka.care
• Flexible work arrangements including remote work up to 10 days per year
• Lunch vouchers worth €8.50 per working day, with partial company coverage
• Subsidies for sports club memberships or creative classes through the work council
• 50% reimbursement for public transportation subscriptions
• ParentCare Program providing full salary coverage during initial parental leave months
• Participation in Doctolib's long-term employee value sharing plan, DoctoGrowth
• Additional support for caregivers and employees with disabilities, including remote work adaptations and psychological support
• Relocation assistance for international candidates
• Access to advanced AI tools, training, and development resources

Equal Opportunity

At Doctolib, we are committed to fostering an inclusive and diverse workplace. We evaluate all candidates based on their qualifications and motivation, without discrimination based on gender, religion, age, sexual orientation, ethnicity, or disability. We encourage applications from individuals of all backgrounds and experiences. To support a fair hiring process, we kindly ask applicants to exclude personal information such as photographs or age from their applications. If you require accommodations during the recruitment process, please let us know. We believe that diverse perspectives drive innovation and help us build better healthcare solutions for everyone.