Principal Site Reliability Engineer

Real innovation starts with a strong foundation and at commercetools that comes from the perfect balance of our product and our people.

Behind every leap forward is a collective of builders explorers doers makers and kind of people who not only pioneered a more flexible approach to commerce architecture but also shaped the culture of experimentation that approach unlocked. Together they are the engine of commerce innovation today.

At commercetools we power the next era of autonomous commerce for our customers. Whether its AI-driven solutions that help enterprises make smarter business decisions bridging digital and physical shopping experiences or enabling entirely new ways for industries to connect with their customers we help the worlds most ambitious companies experiment scale and grow without limits.

Here the best idea wins not the loudest voice. You will have the tools trust and space to not only build the future of commerce but to build your own.

You own AI capabilities end-to-end: from the data and context that feed a model through agent orchestration to the generative UI a user sees and trusts. Youve personally shipped and operated full-stack apps in production so backend frontend data and ML arent four teams you coordinate with theyre four things you do. Youre not a research scientist; you wield models and engineer ruthlessly around their uncertainty.

You will:

• Build agent loops and orchestration: tool use structured outputs business-rule enforcement graceful failure
• Build the integration layer (via MCP) that lets agents securely call backend systems and business APIs
• Render model output into live streamed accessible UI via generative-UI protocols
• Ground models in real data: retrieval embeddings and feedback loops that actually close
• Treat evals as a first-class system - provable improvement not vibes
• Take a capability from prompt-in-a-notebook to a measured guard-railed production feature

This role is to based in our hubs - Berlin Boston Durham Munich London or Valencia.

Youre a creative problem-solver who is wired to find solutions. You confidently dive into complex challenges and have a talent for making them simple for others. Your curiosity drives you to constantly grow and contribute to an environment of trust and teamwork. Great ideas come from many paths and your unique perspective matters more than checking every box. What matters most is the mindset you bring to the work.

You bring:

• Shipped full-stack apps to production and owned them end-to-end: frontend through backend to deploy and operate not handed off at a layer boundary
• 5 years shipping production software 2 building with LLMs in production (real users not demos)
• Hands-on experience with UI protocols (A2UI AG-UI MCP-UI or similar). Youve built against a generative/agent-driven UI protocol not just consumed a REST API
• The AI spine: prompt/context engineering agents tool use structured outputs evals MCP Python and TypeScript/Node React; comfortable with async streaming and observability
• Working fluency with retrieval/embeddings and SQL

Nice to Have:

• Fine-tuning/distillation e-commerce or marketplace systems and a track record in 01