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Commerzbank, a leading international commercial bank with operations in nearly 50 countries, is expanding its Digital Technology Center in Sofia, Bulgaria. You will join flexhub, Commerzbank's internal delivery capability—a team of engineers, architects, analysts, and experts working directly with business units across the organization. Unlike external consultancies, flexhub colleagues stay embedded in the bank, driving high-priority initiatives while building lasting internal expertise. Based in Frankfurt, Sofia, and Łódź, the team combines consulting variety with corporate stability: you'll join different teams across the bank when your expertise is needed, then move to the next challenge, building strong internal knowledge without sales targets or utilization pressure.
Your responsibilities will include:
- Developing and refining complex prompts and chains to solve specific business problems
- Working with developers to integrate LLM capabilities into wider application architectures
- Implementing RAG (Retrieval-Augmented Generation) pipelines to ground model responses in factual data
- Establishing evaluation metrics to measure prompt performance and detect drift
- Debugging complex chains and resolving issues related to hallucinations or latency
- Creating automated test suites for prompt regression testing
- Contributing to the internal library of prompt patterns and best practices
- Explaining technical AI limitations and capabilities to product owners
- Sharing learnings with immediate colleagues and supporting team goals
The role offers good work-life balance with 25 days annual paid leave (increasing to 31 days), flexible working hours, work-from-home and work-from-abroad opportunities, luxury health and dental insurance, EUR 80 monthly food vouchers, 6 additional days off for exceptional circumstances, employee assistance programs, multisport card, annual EUR 153.39 net contribution per child for summer camps/school/kindergarten (up to age 15), and access to training, certifications, and conferences for professional development. You'll work in a friendly, supportive, multicultural environment within a stable, 150-year-old company contributing to a newly launched Digital Technology Center.
REQUIREMENTS:
- Good knowledge of Python for developing, testing, and integrating AI-driven applications
- Practical experience with Generative AI and prompt engineering to design effective, reliable LLM-based solutions
- Hands-on experience using LangChain to build modular, production-ready LLM workflows
- Good understanding of Retrieval-Augmented Generation (RAG) and vector databases for semantic search and context-aware responses
- Experience with model fine-tuning to adapt foundation models to domain-specific requirements
- Strong skills in API integration to connect AI services with existing systems and products
- Familiarity with agentic AI workflows, orchestrating multi-step, tool-using AI agents for complex tasks
- High flexibility and adaptability to a fast-changing environment
- Strong team player with high ability to work in international teams
- CV in English required
