Senior Machine Learning Engineer – LLMs

Join our AI team at Prosus, the largest consumer internet company in Europe and one of the biggest tech investors in the world. You'll be working on the team that drives growth and innovation across the company, with your work directly impacting how millions of people shop online.
Who we’re looking for
We're seeking a seasoned Senior ML Engineer with an LLM specialization to build state-of-the-art language models and steer the execution of AI projects. You have a strong track record of shipping production-grade AI systems, particularly LLM-based solutions, and excel at translating research concepts and promising ideas into tangible business impact. You possess deep, hands-on experience with the practicalities of LLM development, from fine-tuning to API integration, communicate with technical clarity, and are a curious individual who thrives in a fast-moving, impact-driven environment where research insights are practically applied.

What you’ll do

• Steer execution of AI projects, ensuring alignment with team objectives and driving delivery of impactful solutions.
• Formulate and refine experiments from high-level discussions and technical insights, actively contributing to their hands-on implementation and rigorous analysis.
• Develop, train, fine-tune, and deploy LLM-based systems into production environments.
• Own the full ML lifecycle: from data strategy and preparation for LLMs, through model development and robust evaluation, to optimization and production monitoring.
• Develop and integrate solutions leveraging LLM APIs, SDKs, and direct model interactions for advanced applications and agentic systems.

Minimum qualifications

• 5+ years of hands-on experience in machine learning, with a strong focus on NLP and substantial practical work with LLMs (including but not limited to developing, fine-tuning, and deploying transformer-based models).
• Demonstrated success steering and delivering complex ML projects end-to-end, including aligning teams, defining milestones, and ensuring on-time delivery of business-impactful solutions.
• Direct hands-on experience with the full LLM development lifecycle: data curation for LLMs, experiment design and execution, prompt engineering, fine-tuning, evaluation with relevant metrics, and real-world deployment.
• Expert proficiency in Python, and deep familiarity with modern ML tooling (especially PyTorch and the Hugging Face ecosystem).
• Experience integrating and optimizing solutions using commercial and/or open LLM APIs (OpenAI, Anthropic, Google, etc.), including custom prompt design, cost/performance trade-offs, and evaluation.
• Strong foundation in software engineering: version control (Git), CI/CD, testing, monitoring/observability for ML systems, and clear coding/documentation practices.
• Proven ability to translate strategic business goals and high-level technical insights into concrete project plans and actionable, measurable deliverables.
• Excellent communication skills, able to lead discussions with technical and non-technical collaborators, and foster a positive, productive project environment.

Preferred qualifications

• Experience with distributed training and inference on multi-GPU clusters (e.g., familiarity with tools like Axolotl or similar).
• Strong data intuition, particularly a feel for generating or selecting synthetic data that meaningfully boosts LLM performance.
• Hands-on experience building or experimenting with AI agents (even as personal or toy projects).
• Demonstrable curiosity, evidenced by self-initiated projects, deep dives into specific AI topics, or contributions to the AI community.
• A strong personal interest and informed perspective on a particular sub-field or emerging trend within AI/LLMs.
• Clear, empathetic communicator who contributes positively to team dynamics (a good sense of humor helps!).
• Thrives in a fast-paced, impact-driven setting where research insights are valued and practically applied.

What we offer

• High-impact, green-field projects that will shape how millions of people shop online, directly contributing to strategic company goals with significant executive and CEO-level visibility.
• Access to a state-of-the-art GPU fleet (H200s), massive proprietary datasets, and a wide range of open-source and commercial LLMs (e.g., OpenAI, Anthropic, Google, Together.ai).
• A team of highly experienced colleagues who have released top Hugging Face models, authored NeurIPS papers, created well-known benchmarks, and built multiple production AI systems.
• Significant autonomy and freedom to test your ideas end-to-end—if you can prove it works, you can ship it.
• Modern tooling and infrastructure, including access to coding assist