Data Scientist – Generative AI / LLM

We are looking for a freelance Data Scientist with strong Generative AI experience to join a leading bank in Brussels. You will work on concrete GenAI use cases: LLM-powered assistants, RAG over internal data and agentic workflows that support business users.

The role is hands-on: designing, building and industrialising GenAI solutions together with an existing data/GenAI team.

What you will do

• Design and implement LLM applications (question-answering, assistants, document understanding, decision support).
• Build and optimise RAG pipelines (data ingestion, chunking, vector search, evaluation).
• Develop agentic workflows using LangChain / LangGraph or similar (tools, multi-step flows, orchestration).
• Work closely with business stakeholders to understand use cases and translate them into GenAI solutions.
• Explain to non-technical users how to get the best results from prompts and GenAI tools.
• Contribute to good practices around LLMOps (monitoring, evaluation, cost and performance optimisation).

Must-have experience

• 2–5 years in Data Science / ML / AI.
• Strong Python and deep learning background (transformers or similar).
• Hands-on experience with Generative AI and LLMs (GPT, open-source models, etc.) in real projects.
• Practical experience with LangChain or similar framework for building LLM applications.
• Solid experience with RAG and vector databases.
• Exposure to agentic workflows (agents, tools, multi-step reasoning) – or strong interest plus first concrete projects.
• Good understanding of prompt engineering and ability to explain it clearly to business users.
• You speak English fluently and can follow meetings in French or Dutch (you can respond in English).
• Able to work 2–3 days per week onsite in Brussels (50% onsite).

Nice to have

• Experience in banking, insurance or other regulated industries.
• Experience with Azure or another major cloud platform for data / AI.
• Experience with MLOps / LLMOps (MLflow, CI/CD, monitoring, evaluation).

Contract details

• Freelance / contract position.
• Long-term mission (12 months+, extensions likely).