Full Stack Engineer (Senior) - Frankfurt

Senior Full-Stack Engineer Location: Frankfurt, Germany. An exciting opportunity for an experienced FullStack Engineer to join a growing AI StartUps, where you will help build and maintain a high-performance, real-time, server-rendered web application. Because we handle enterprise-grade real-time interactions, precision, type safety, and system resilience are paramount. We need someone who deeply understands browser mechanics, async architectures, and the nuances of server-side rendering. Responsibilities: Real-Time Engine Architecture: Design and maintain resilient WebSocket communication pipelines - handling reconnection strategies, client-server state synchronization, concurrent task coordination, and message validation across boundaries.SSR & Hydration Engineering: Build server-side rendered interfaces with extreme care around hydration correctness, loader patterns, state rehydration, and explicit server-versus-client code splitting.Type Safety & Runtime Guardrails: Enforce end-to-end type safety using strict TypeScript on the client and runtime validation at all untrusted system boundaries (APIs, WebSockets, and state payloads).Testing & Release Discipline: Maintain a high quality bar through comprehensive test suites (unit, integration, and browser-level E2E) and disciplined development practices (e.g., conventional commits).Containerized Deployment: Package, deploy, and monitor front-end and BFF microservices using Docker and Kubernetes. Requirements: Strict TypeScript & React Mastery: Deep expertise in modern React patterns, state management, complex browser DOM mechanics, and strict compile-time type enforcement.Advanced knowledge of asynchronous programming paradigms, Event Loops, WebSockets lifecycle management, client-side caching, and streaming state.Solid proficiency with Python async frameworks (FastAPI, WebSockets, asyncio) to build and maintain robust backend-for-frontend layers.Dedication to rigorous testing (Jest, React Testing Library, Playwright/Cypress) and clean code hygiene (conventional commits, static analysis, CI/CD pipelines).Practical experience containerizing front-end applications, managing multi-stage Docker builds, and deploying workloads on Kubernetes. By applying to this role you understand that we may collect your personal data and store and process it on our systems. For more information please see our Privacy Notice (https://eu-recruit.com/about-us/privacy-notice/)