Senior Software Engineer - Node.js/TypeScript (x/f/m)

<h2><strong>Set a new pulse for healthcare!</strong></h2> <p>We are looking for a <strong>Senior Software Engineer</strong> to join the <strong>DIAL</strong> team in the <strong>Phone Assistant</strong> domain.</p> <p>Your mission will be to design, build, and scale the AI-powered features that transform how practitioners and patients connect over the phone — making care more accessible for patients and reducing administrative burden for health professionals. You will work in a feature team developing the Phone Assistant, Doctolib's solution that combines LLM reasoning, speech recognition, and real-time backend systems, launching first in Germany and expanding to France and Italy.&nbsp;</p> <p>Working in the tech team at Doctolib means building innovative products and features to improve the daily lives of care teams and patients.</p> <h2><strong>What you'll do</strong></h2> <p>Your responsibilities include but are not limited to:</p> <ul> <li>Build and operate backend services in <strong>Node.js/TypeScript</strong> (with Python exposure), designing for reliability, scalability, and real-time performance</li> <li>Design, evaluate, and ship <strong>LLM-based features</strong> end-to-end: prompt engineering, tool calling, structured outputs, guardrails, and fallback strategies</li> <li>Own AI feature quality: build evaluation datasets and scorers (e.g., in Braintrust), track regressions, and make evidence-based ship decisions before each release</li> <li>Deploy and operate cloud-native services on <strong>Kubernetes</strong> across major cloud providers (AWS/Azure/GCP), and evolve CI/CD pipelines with <strong>GitHub Actions</strong></li> <li>Design data models and drive database migrations and performance tuning for real-time workloads (<strong>PostgreSQL</strong>: connection pooling, indexing, query optimisation)</li> <li>Maintain a high testing bar (unit, integration, e2e), debug distributed systems in production with strong observability, and contribute to pragmatic, secure architecture decisions</li> </ul> <h2><strong>Who you are</strong></h2> <p>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.</p> <p><strong>You'll be a great fit if you:</strong></p> <ul> <li>Have 5+ years of backend engineering experience building scalable, resilient systems in <strong>Node.js/TypeScript</strong> (with some Python)</li> <li>Have hands-on production experience building LLM-based features: prompting, tool calling, structured outputs, eval frameworks, and handling real-world failure modes</li> <li>Have proven experience deploying and operating services on <strong>Kubernetes</strong> within at least one major cloud provider (AWS, Azure, or GCP), with solid CI/CD practices</li> <li>Have a strong testing culture (unit/integration/e2e), sharp debugging skills for microservices and distributed systems, and a focus on code quality</li> <li>Are fluent in English, with a collaborative mindset and the drive to own problems end-to-end — from design to production</li> </ul> <p><strong>It would be fantastic if you:</strong></p> <ul> <li>Have experience with speech pipelines (ASR, TTS, streaming audio) or voice agents</li> <li>Are familiar with event-driven architectures and message brokers (Kafka, RabbitMQ, NATS, or Redis Streams), and have hands-on PostgreSQL experience (EXPLAIN/ANALYZE, indexing strategies, connection pooling)</li> <li>Have an interest in telephony and real-time communication (SIP, RTP, WebRTC) — no prior experience needed, we will teach you</li> </ul> <h2><strong>Life at Doctolib Tech</strong></h2> <ul> <li>Our solutions are built on a single fully cloud-native platform that supports web and mobile app interfaces, multiple languages, and is adapted to country and healthcare specialty requirements.</li> <li>Our stack is composed of Rails, TypeScript, Java, Python, Kotlin, Swift, and React Native.</li> <li>We leverage AI ethically across our products to empower patients and health professionals. Discover our AI vision<a href="https://careers.doctolib.com/ai-careers/"> here</a>.</li> </ul> <p><em>Want to learn more about our tech culture and environment? Visit the</em><a href="https://careers.doctolib.com/tech-doctolib/"><em> </em><em>Doctolib Tech