ML Engineer — NLP (Polish)

KIEFER is building Greece's integrated AI ecosystem. From renewable energy infrastructure and AI systems to robotics and enterprise applications, we connect the technologies that power Europe's intelligent future. Founded in 2014, KIEFER has delivered 600MW+ of energy projects and is now developing sovereign AI infrastructure, enterprise AI products and physical AI systems for Greece and Southeast Europe.

We are looking for an ML Engineer to improve how our language models work for Polish users. You will measure quality on real product tasks, build Polish-language data and evaluations, and improve models where the results show gaps.

Your work will help us understand which Polish-language use cases are ready for launch. The methods you build should also be useful as we expand to other languages.

• Define priority Polish-language use cases and quality targets with Product and go-to-market teams.
• Measure current model quality in Polish and investigate errors in language use, terminology, and user tasks.
• Build Polish-language datasets and evaluations, using native-speaker review where needed.
• Improve model quality through better data, fine-tuning, post-training, or other adaptation methods.
• Set up regression tests, quality checks, and monitoring for Polish-language model updates.
• Use evaluation results and market feedback to identify remaining gaps and recommend next steps.

• 3+ years of hands-on ML or NLP engineering experience, including work on a non-English or multilingual system in production.
• Strong Python skills and experience with PyTorch, JAX, TensorFlow, or a similar ML framework.
• Experience building evaluations that reflect real user tasks and combine automatic metrics with human review.
• Experience preparing and checking language datasets and building reliable data pipelines.
• Hands-on experience fine-tuning, post-training, or adapting NLP or LLM models and measuring the results.
• Strong software engineering and production ML skills, including model versioning, regression testing, and monitoring.
• Professional working proficiency or native-level fluency in Polish.
• Experience improving an AI or NLP product for a new language or market.
• Research or open-source work in multilingual NLP or model evaluation.

What is there for you

• Compensation: Competitive package aligned with talent benchmarks.
• Impact: Hands-on work shaping AI capabilities for Kiefer Tech’s products and real-world applications.
• AI-native environment: Real challenges across model development, evaluation, and production AI systems.
• Culture: Engineering-first, high autonomy, low bureaucracy, and space to shape meaningful AI products.