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

SET A NEW PULSE FOR HEALTHCARE! We are looking for a Senior Software Engineer to join the DIAL team in the Phone Assistant domain. 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. Working in the tech team at Doctolib means building innovative products and features to improve the daily lives of care teams and patients. WHAT YOU'LL DO Your responsibilities include but are not limited to: - Build and operate backend services in Node.js/TypeScript (with Python exposure), designing for reliability, scalability, and real-time performance - Design, evaluate, and ship LLM-based features end-to-end: prompt engineering, tool calling, structured outputs, guardrails, and fallback strategies - Own AI feature quality: build evaluation datasets and scorers (e.g., in Braintrust), track regressions, and make evidence-based ship decisions before each release - Deploy and operate cloud-native services on Kubernetes across major cloud providers (AWS/Azure/GCP), and evolve CI/CD pipelines with GitHub Actions - Design data models and drive database migrations and performance tuning for real-time workloads (PostgreSQL: connection pooling, indexing, query optimisation) - Maintain a high testing bar (unit, integration, e2e), debug distributed systems in production with strong observability, and contribute to pragmatic, secure architecture decisions 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 5+ years of backend engineering experience building scalable, resilient systems in Node.js/TypeScript (with some Python) - Have hands-on production experience building LLM-based features: prompting, tool calling, structured outputs, eval frameworks, and handling real-world failure modes - Have proven experience deploying and operating services on Kubernetes within at least one major cloud provider (AWS, Azure, or GCP), with solid CI/CD practices - Have a strong testing culture (unit/integration/e2e), sharp debugging skills for microservices and distributed systems, and a focus on code quality - Are fluent in English, with a collaborative mindset and the drive to own problems end-to-end — from design to production It would be fantastic if you: - Have experience with speech pipelines (ASR, TTS, streaming audio) or voice agents - 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) - Have an interest in telephony and real-time communication (SIP, RTP, WebRTC) — no prior experience needed, we will teach you LIFE AT DOCTOLIB TECH - 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. - Our stack is composed of Rails, TypeScript, Java, Python, Kotlin, Swift, and React Native. - We leverage AI ethically across our products to empower patients and health professionals. Discover our AI vision here https://careers.doctolib.com/ai-careers/. Want to learn more about our tech culture and environment? Visit the Doctolib Tech site https://careers.doctolib.com/tech-doctolib/. 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 includes one month additional parental leave and much more - Enrollment in Doctolib's long-term employee value sharing plan called DoctoGrowth - Free mental health and coaching services through our partner Moka.care - Subsidized sports membership through our partner Urban Sports Club - A flexible workplace policy offering both hybrid and office-based mode - Alongside healthy snacks and our regular breakfast buffet, we provide a subsidized meal benefit - 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 OUR INTERVIEW PROCESS - Recruiter Interview - Live Coding Interview - System Design Interview - Behavioral Interview - At least one reference check We want your experience to be clear, respectful, and transparent. Learn more about our hiring process on our candidate experience page https://careers.doctolib.com/tech-doctolib/getting-hired/. JOB DETAILS - Permanent position - Tech stack: Node.js/TypeScript, Python, Kubernetes, AWS/Azure/GCP, PostgreSQL - Full-time - Berlin - Hybrid work setup (up to 2 remote days per week) - Start date: as soon as possible WE WELCOME EVERYONE 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 al