Backend Engineer - AI Agents (all genders)

What You'll Be Working On

At Lime Connect, AI agents already handle customer service conversations for our clients. Now we want to make them better: measurably, and regardless of which language model is currently ahead. That's why we're looking for someone with a backend background who feels at home in the AI world:

• You build and improve our AI agents, from the agent loop and tool calling to context management.
• You set up our architecture so we can switch language models without rebuilding everything.
• Before anything goes live, you use evals to check whether it's actually better. For example, with LLM-as-a-judge and test cases from real customer conversations.
• You turn feedback from the service teams working with our agents into concrete improvements. That way, the system keeps getting better step by step.
• You connect APIs, MCP tools and website crawling, so our agents have the right knowledge and the right tools.
• Within the backend team, you're the go-to person for AI and work closely with Product.

What Makes You a Fit

• Around five years of backend development, including at least a year building language-model features that real users rely on.
• You've built AI agents before and know what context windows, tool calling and prompting mean in practice.
• You've worked hands-on with RAG and vector databases.
• You have experience with evals, for example with Langfuse, Arize Phoenix or LangSmith, or you've built something similar yourself.
• Ideally, you know Pydantic AI, LiteLLM or similar libraries.
• You follow what's happening in AI, try new things quickly and take ownership of your topics.
• You speak German and English fluently.

What’s in It for You

• 600 € health budget per year, including 24/7 medical advice - also for family members in your household
• Subsidised Urban Sports Club membership (20 € monthly contribution)

• Learning budget for courses, books and conferences
• Free access to Udemy, Masterclass and language learning apps
• Leadership programmes such as "Next Gen" and "Effective Manager"

• Weekly FIKA, movie nights, book club and regular get-togethers and team events
• International summer party together with our colleagues in the Nordics

• Office-first setup: 3 days in our Cologne office at the MediaPark, 2 days remote
• 360° view across Cologne from the 14th floor
• Workation within the EU
• Snacks, cereal bar and drinks in the office

• Company pension scheme via Zurich with a 30 % employer contribution
• Job ticket or mobility budget, plus free parking at the MediaPark
• Corporate benefits
• 28 days of holiday, plus Christmas Eve and New Year's Eve off
• Up to 5 days of special leave for important life events