Senior Backend Engineer - Java/Kotlin (x/f/m)

Senior Backend Engineer - Java/Kotlin (x/f/m) Set a new pulse for healthcare! We are looking for a Senior Backend Engineer to join the IAM (Identity and Access Management) team in Platform Services Tech . Your mission will be to secure and scale the authentication capabilities that millions of Doctolib users rely on every day. You will drive the most impactful phases of a critical, multi-year migration to a self-hosted, Keycloak-based identity provider — a project at the intersection of platform engineering, security, and cross-team impact. 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: Lead the next phases of the multi-year authentication migration to a self-hosted, Keycloak-based identity provider — completing token-based sign-in for Doctolib Pro apps and making the identity provider the single source of truth for user data Own the reliability of high-traffic authentication systems end-to-end: monitoring, alerting, SLOs, incident resolution, post-mortems, and safe rollout practices (feature flags, canary releases, zero-downtime migrations) Drive cross-team delivery independently: produce design documents and decision memos, build alignment across dependent teams, and make trade-offs explicit Collaborate closely with the Product Security team on security-sensitive architecture decisions and changes Contribute to frontend development in React and TypeScript on the custom interfaces tied to the IAM platform Use AI tools daily to accelerate your own work and help establish repeatable AI-augmented workflows across the team 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 7–10+ years of backend engineering experience with hands-on, daily Java or Kotlin development and a solid understanding of JVM internals (garbage collection, memory management, multi-threading, and profiling) Have proven experience building and operating high-traffic production systems at scale — load testing, capacity planning, horizontal scaling, caching, and performance bottleneck identification Own reliability end-to-end: you define monitoring, alerting, and SLOs, lead incident resolution, write post-mortems, and have shipped changes safely via feature flags, canary releases, and zero-downtime migrations on live systems Have led complex, multi-week cross-team delivery independently — producing design docs, driving alignment across dependent teams, and making trade-offs explicit without waiting for consensus Use AI tools daily in your engineering workflow, critically validate their outputs, and are excited to help establish shared AI practices for your team Are fluent in English (written and spoken) It would be fantastic if you: Have prior experience with identi