Senior Expert Platform Engineer (m/f/d)

WHAT YOU'LL DO  We are looking for a Senior Software Engineer to join the Patient Online Booking feature team in the Patient Health Platform domain. Our team is responsible for enhancing the booking experience for our 90 million patients, with over 300 million appointments expected to be booked this year. Empower your team to build better products, playing a pivotal role in the improvement of one of France’s most downloaded apps! Your responsibilities include but are not limited to: * Collaborate with product managers, designers, and other engineers to define and implement features to improve healthcare access for patients * Take a leading role within the team and contribute to establishing a technical vision that ensures the performance, security, and usability of the application, taking into account the future needs and the high scalability needs. * Bring your expertise and experiences to help us continuously improve the way we design, implement, test, and monitor high-quality features * Improving the performance of key features implemented in Java and Ruby on Rails, sometimes completely challenging the status quo * Taking leadership on delivering roadmap items (together with the team) * Contributing to establishing a technical vision and co-drive the creation of the roadmap for next quarters WHO YOU ARE If you don’t meet all the requirements below but believe this opportunity matches your expectations and experience, we still encourage you to apply! * You are proactive, curious, collaborative and eager to learn * You are primarily a backend engineer with expert knowledge of Java and a good knowledge of Ruby on Rails (or similar frameworks). You have a solid understanding of web technologies and software development life cycle * You have a “user first” mindset and want to build a product focused on bringing value to its users, through secure, well-tested and pragmatic code * You embrace and champion AI-augmented engineering, leveraging AI coding tools (GitHub Copilot, Claude Code...) to boost your own productivity and help the team adopt these practices effectively * You are fluent in English WHAT WE OFFER * Free comprehensive health insurance for you and your children * 25 days of paid vacation per year, plus up to 14 days of RTT * Free mental health and coaching services through our partner Moka.care * Work from abroad for up to 10 days per year thanks to our flexibility days policy * Lunch vouchers (Swile card) worth €8.50 per working day, with €4.50 covered by Doctolib * A subsidy from the work council to refund part of the membership to a sport club or a creative class * 50% reimbursement of your public transport subscription * Parent Care Program: receive one additional month of leave on top of the legal parental leave * For caregivers and workers with disabilities, a package including an adaptation of the remote policy, extra days off for medical reasons, and psychological support * Relocation support in case of international mobility * Access to the best AI tools for coding, development and dedicated training THE INTERVIEW PROCESS  * Recruiter Interview * Live Coding Interview * System Design Interview * Behavioral Interview * At least one reference check JOB DETAILS * Permanent position * Full Time * Based in Levallois-Perret * Hybrid position 3 days/week in the office * Start date: As soon as possible If you would like to find out more about tech life at Doctolib, feel free to read our latest Medium blog articles!  At Doctolib, we are committed to improving access to healthcare for everyone. This translates into our recruitment process. We evaluate candidates based solely on qualifications and motivation, without any form of discrimination. The more diverse ideas are heard, the more our product will truly improve healthcare for all. You are welcome to apply to Doctolib, regardless of your gender, religion, age, sexual orientation, ethnicity, disability. To ensure equal opportunities, we invite you to exclude personal information (e.g. pictures, age) from your applications. If you require any accommodation, please let us know for support during the hiring process.  Join us in building the healthcare we all dream of! All information provided is processed by Doctolib for application management. For data processing details, click here. Please contact hr.dataprivacy(at)doctolib.com for inquiries or to exercise your rights.

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 * Free comprehensive health insurance for you and your children * 25 days of paid vacation per year, plus up to 14 days of RTT * Free mental health and coaching services through our partner Moka.care * Work from abroad for up to 10 days per year thanks to our flexibility days policy * Lunch vouchers with Swile card (€8.50 value, €4.50 covered by Doctolib) * Work Council subsidy for sports club memberships or creative classes * 50% reimbursement of your public transport subscription * Parent Care Program: one additional month of leave on top of legal parental leave * For caregivers and workers with disabilities: remote policy adaptation, extra medical leave, and psychological support * Relocation support for international mobility * Access to premium AI tools for development and dedicated training   The interview process * HR Screen * Hiring Manager Interview * Technical Interview * Technical Case Study * Behavioral Interview * At least one reference check We want your experience to be clear, respectful, and transparent. Learn more on our candidate experience page.   Job details * Permanent position * Full-time * Paris, France * Hybrid work mode (up to 2 remote days per week) * Start date: as soon as possible   We welcome everyone At 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 privacy All 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.