Senior Software Engineer – Node.js​/TypeScript; x​/f​/m

What you’ll do

• Build and operate backend services in Node.js/Type Script (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 Git Hub 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

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.

• Have 5+ years of backend engineering experience building scalable, resilient systems in Node.js/Type Script (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

• 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

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, Type Script, 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.

• 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 Docto Growth
• 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…