Principal ML Engineer

YOUR PROFILE

• Ranking & recommendation experience: You've built, evaluated, and improved ranking or recommendation models (learning to rank, reranking, recommender systems), ideally in production with measurable product impact.
• End-to-end ownership: You've personally taken features from the product problem through data, modelling, and the production service to real users.
• Product judgment: You understand the business problem, make pragmatic decisions quickly, and know when something is good enough to ship.
• Strong ML & deep learning background: You have 5+ years building, training, and shipping machine learning models — classical ML and deep learning — in production. You're fluent in a modern deep learning framework, ideally PyTorch.
• Strong Python: You have 5+ years writing production-grade Python. You write clean, well-structured code.
• Experimentation rigor: You know how to evaluate models properly — offline metrics, online A/B tests — and let the data decide.
• Opinionated and pragmatic: You look at a complex system, quickly identify what matters, and make the call. When you're unsure, you find out with data.

We're open on level. If you're at staff level or above, we'd love to hear from you.

BONUS

• Hands-on experience building and deploying LLM or agent systems — RAG, tool use, evals
• TypeScript, React, or Node experience to help integrate your work into our web app
• Experience building search systems or pricing models
• Experience with embedding models, fine-tuning, or model training at scale
• Domain exposure to construction, procurement, or marketplaces

WHY US

• Shape a product that solves real-life problems in the construction industry
• Work in an open-minded, collaborative, dynamic, and international team
• Fully remote team and work culture
• Freedom in your working hours. It's the results that count.
• Company off-sites and regular team events (offline and online)
• Flexible working conditions with the possibility to do workations
• Competitive compensation, a permanent contract, and modern work equipment
• Open feedback culture with regular 1-on-1s

ABOUT US

Cosuno – Revolutionizing construction through technology.

We are Cosuno – a fast-growing tech startup that is making the construction industry more efficient and transparent with our digital platform for tenders and procurement processes. Our goal: to solve the most complex challenges in the industry with innovation and simplicity.

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Posted Nov 01, 2026

Source: Statistisches Bundesamt (Destatis), table; dl-de/by-2-0; StarIn's calculation