Senior Software Engineer - Node.js/TypeScript

Join the DIAL team in the Phone Assistant domain to design, build, and scale AI-powered features that transform how practitioners and patients connect over the phone. You will develop 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.

What you'll do

• 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

What you'll need

• 5+ years of backend engineering experience building scalable, resilient systems in Node.js/TypeScript (with some Python)
• Hands-on production experience building LLM-based features: prompting, tool calling, structured outputs, eval frameworks, and handling real-world failure modes
• Proven experience deploying and operating services on Kubernetes within at least one major cloud provider (AWS, Azure, or GCP), with solid CI/CD practices
• Strong testing culture (unit/integration/e2e), sharp debugging skills for microservices and distributed systems, and focus on code quality
• Fluency in English, collaborative mindset, and drive to own problems end-to-end from design to production

Nice to have

• Experience with speech pipelines (ASR, TTS, streaming audio) or voice agents
• Familiarity with event-driven architectures and message brokers (Kafka, RabbitMQ, NATS, or Redis Streams), and hands-on PostgreSQL experience (EXPLAIN/ANALYZE, indexing strategies, connection pooling)
• Interest in telephony and real-time communication (SIP, RTP, WebRTC)

What they offer

• Deutschlandticket (Germany-wide public transport pass) fully paid
• 28 vacation days + 1 additional day for each full calendar year of employment (up to 30 days maximum)
• Work from abroad up to 10 days per year through flexibility days policy
• Company health insurance with supplementary benefits through Allianz
• Company pension scheme (bAV) through Allianz with 40% employer subsidy
• Free mental health and coaching services through Moka.care