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Doctolib is seeking a Senior Software Engineer to join the DIAL team in the Phone Assistant domain. You will design, build, and scale AI-powered features that transform how practitioners and patients connect over the phone, making care more accessible and reducing administrative burden for health professionals.
You will work in a feature team developing the Phone Assistant, Doctolib's solution combining LLM reasoning, speech recognition, and real-time backend systems, launching first in Germany and expanding to France and Italy.
Key Responsibilities:
- 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 by building evaluation datasets and scorers (e.g., in Braintrust), tracking regressions, and making 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 optimization)
- Maintain a high testing bar (unit, integration, e2e), debug distributed systems in production with strong observability, and contribute to pragmatic, secure architecture decisions
Doctolib's tech stack includes Rails, TypeScript, Java, Python, Kotlin, Swift, and React Native. The company leverages AI ethically across products to empower patients and health professionals.
Work Environment:
Hybrid setup with up to 2 remote days per week. Permanent, full-time position starting as soon as possible. Benefits include 28 vacation days (plus 1 additional day per year of employment, up to 30), Deutschlandticket (Germany-wide public transport), company health insurance with supplementary benefits, pension scheme with 40% employer subsidy, parental leave program, mental health services, subsidized sports membership, flexible workplace policy, relocation support, and access to AI tools for development.
Requirements:
- 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
- Fluent in English with 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, Redis Streams)
- Hands-on PostgreSQL experience (EXPLAIN/ANALYZE, indexing strategies, connection pooling)
- Interest in telephony and real-time communication (SIP, RTP, WebRTC)
