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 role

We’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 offer

• Full-time, reliable, permanent employment
• Flexible working hours
• Hybrid setup: remote-first, with office space in Berlin
• Competitive salary
• 28 days of paid vacation
• Modern hardware and software provided by us
• Open, friendly team culture where every voice matters
• Work on a product tested by professional clubs and athletes
• Early access to real sports performance data and the opportunity to shape the foundation for AI/ML integrations
• Build scalable backend infrastructure that connects Unity VR, web dashboards, and analytics systems

Your tasks

• Take ownership of an existing project written in TypeScript
• Build and maintain secure RESTful APIs (JSON) to connect Unity-based VR applications with backend services
• Manage and optimize our Google Cloud Platform (GCP) backend infrastructure
• Develop endpoints for session handling, tracking data, and user feedback
• Implement and maintain secure authentication and account systems
• Design and manage data structures for motion data, event logs, and performance metrics
• Develop and manage API endpoints for ML model integration, enabling model inference and data exchange between Python-based ML systems and the Node.js backend
• Collaborate with ML engineers and data scientists to integrate pose estimation, biomechanics, and predictive feedback models
• Ensure smooth data flow between C#/Unity clients and backend + ML services (via REST/gRPC)
• Guarantee data security, performance, and scalability across systems
• Write clear technical documentation in our internal wiki
• Collaborate closely with the frontend developer, Unity engineers, and CTO
• Participate 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 development
• Proficiency in Node.js and TypeScript
• Experience with Express.js or similar backend frameworks (e.g. NestJS)
• Familiarity with MongoDB and/or PostgreSQL
• Experience 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 Actions
• Understanding 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 data
• Capable of communicating complex concepts clearly and effectively
• Analytical mindset and self-driven work ethic
• Fluent in English (German is a plus)
• Knowledge of Unity and C# is a strong advantage for integrating the VR client
• Bonus: experience with localization, multi-language support, or multi-tenant systems
• Optional: experience working with machine learning pipelines, FastAPI, or model serving environments (TensorFlow Serving, BentoML, etc.)

Nice to have:

• Background in sports, biomechanics, or performance analytics
• Familiarity with pose estimation frameworks (e.g. MediaPipe, OpenPose, MMPose)
• Experience integrating 3D or motion data into backend systems
• Interest in AI-driven feedback systems and data visualization