Backend Developer (Node.js / TypeScript)

We’re building Apollo – a next-generation training and analytics platform for elite football and tennis, combining virtual reality, real-time biomechanical feedback, and AI-based performance analytics. Our software is already being tested by Bundesliga clubs and world-class athletes.Currently, the core system is built in Unity (C#). We are now expanding our backend layer to enable data-driven insights, machine learning integration, and cloud scalability. Your roleWe’re looking for an experienced backend developer who can take ownership of the existing backend and evolve it into a robust, scalable system ready for AI and ML integration.You will collaborate closely with our frontend, Unity, and ML teams, ensuring seamless communication between the VR engine, databases, analytics services, and cloud infrastructure.Preferably, you are within ±2 hours of CET (remote possible).If you are a senior full-stack developer, feel free to apply as well. We offerFull-time, reliable, permanent employmentFlexible working hoursHybrid setup: remote-first, with office space in BerlinCompetitive salary28 days of paid vacationModern hardware and software provided by usOpen, friendly team culture where every voice mattersWork on a product tested by professional clubs and athletesEarly access to real sports performance data and the opportunity to shape the foundation for AI/ML integrationsBuild scalable backend infrastructure that connects Unity VR, web dashboards, and analytics systems Your tasksTake ownership of an existing project written in TypeScriptBuild and maintain secure RESTful APIs (JSON) to connect Unity-based VR applications with backend servicesManage and optimize our Google Cloud Platform (GCP) backend infrastructureDevelop endpoints for session handling, tracking data, and user feedbackImplement and maintain secure authentication and account systemsDesign and manage data structures for motion data, event logs, and performance metricsDevelop and manage API endpoints for ML model integration, enabling model inference and data exchange between Python-based ML systems and the Node.js backendCollaborate with ML engineers and data scientists to integrate pose estimation, biomechanics, and predictive feedback modelsEnsure smooth data flow between C#/Unity clients and backend + ML services (via REST/gRPC)Guarantee data security, performance, and scalability across systemsWrite clear technical documentation in our internal wikiCollaborate closely with the frontend developer, Unity engineers, and CTOParticipate in designing architecture for a multi-tenant SaaS environment, enabling scalability across multiple teams and clubs Your skills:3+ years of professional experience in backend or full-stack developmentProficiency in Node.js and TypeScriptExperience with Express.js or similar backend frameworks (e.g. NestJS)Familiarity with MongoDB and/or PostgreSQLExperience with Google Cloud Platform (GCP) (Cloud Run, Firestore, Cloud Functions)Solid understanding of API design for system integration (REST, gRPC)Experience with data-heavy systems (streaming, analytics, or sensor data)Knowledge of CI/CD pipelines, Docker, and GitHub ActionsUnderstanding of data processing workflows (ETL, JSON pipelines) and real-time event communication (WebSockets, Socket.io)Motivation and ability to build secure, scalable systems for sensitive sports dataCapable of communicating complex concepts clearly and effectivelyAnalytical mindset and self-driven work ethicFluent in English (German is a plus)Knowledge of Unity and C# is a strong advantage for integrating the VR clientBonus: experience with localization, multi-language support, or multi-tenant systemsOptional: experience working with machine learning pipelines, FastAPI, or model serving environments (TensorFlow Serving, BentoML, etc.) Nice to have:Background in sports, biomechanics, or performance analyticsFamiliarity with pose estimation frameworks (e.g. MediaPipe, OpenPose, MMPose)Experience integrating 3D or motion data into backend systemsInterest in AI-driven feedback systems and data visualization