(Junior) Data Scientist (m/w/d) Search / AI Forge

About the Position

CHECK24 is the comparison portal: market leader and dynamic start-up at the same time. In agile teams, we make quick decisions and live flat hierarchies. With the latest tools, technologies, and state-of-the-art AI methods, we drive data-driven innovation – always with the goal of creating real value for our customers. Across more than 50 products, we work daily to improve the user experience for our more than 20 million customers.

Our Search Team within the CHECK24 AI Forge develops scalable AI solutions for search and ranking across various CHECK24 products. Search is a central entry and navigation point for our customers and covers sophisticated domains – from e-commerce product search and web-based navigation to travel search for hotels, destinations, and other products.

Search and ranking are among the most challenging disciplines in applied machine learning. A good system must understand user intent, retrieve relevant candidates, rank them effectively, and meet high requirements for latency, scalability, and measurable customer benefit. Many of the questions we work on are technically complex and cannot be answered with standard solutions – analytical, hypothesis-driven approaches as well as solid engineering are required.

To strengthen our team, we are looking for someone with initial practical experience who thinks systematically about complex problems, rigorously evaluates approaches, and wants to develop into a strong Applied Machine Learning Engineer (m/w/d). You will work on production systems that combine classical information retrieval methods, deep learning, embeddings, and large language models, and you will accompany the entire lifecycle – from the initial idea through evaluation to deployment, monitoring, and continuous improvement. A particular focus is on agentic workflows: the design, evaluation, and productive use of systems that independently use tools and solve multi-step tasks.

We look forward to your application as a (Junior) Data Scientist (m/w/d) Search at the CHECK24 AI Forge GmbH.

Responsibilities

• You create reliable evaluation datasets and metrics and validate improvements through offline evaluations, user signals, and A/B tests
• You research promising approaches in information retrieval, recommender systems, and large language models and translate them into measurable customer benefits
• In model development, you focus on training, fine-tuning, and systematic evaluation – with a focus on semantic search, relevance prediction, and learning-to-rank
• You develop and improve ML services for retrieval, ranking, query understanding, and classification
• For hybrid search solutions, you combine lexical retrieval, embeddings, neural models, and LLM-based components
• Together with the team, you transition prototypes into production-ready services – using technologies such as Python, FastAPI, Docker, PyTorch, and vector databases
• For efficient prototyping, testing, and continuous improvements, you use modern AI-assisted and agentic engineering workflows

Requirements

• You have successfully completed a degree (usually Master) in computer science, mathematics, statistics, physics, electrical engineering, or a comparable quantitative field, with strong grades in quantitative subjects
• A solid understanding of ML basics and systematic model evaluation allows you to evaluate model performance, test hypotheses, and justify improvements comprehensibly
• You bring at least one year of relevant practical experience in machine learning or data science, including from internships, work-study programs, or personal projects
• Strong Python skills and practical experience with ML or deep learning frameworks such as PyTorch are part of your technical toolkit
• Solid classical ML skills such as gradient boosting, regression, and feature engineering are evident in your resume – beyond LLM or RAG applications
• You have practical experience with LLM-based applications, LLM evaluation, tool use, or agentic workflows
• Practical experience with APIs (e.g., FastAPI), containers, and Git – ideally including a self-deployed service – complements your interest in building complete, production-ready systems
• Knowledge in information retrieval, semantic search, recommender systems, or learning-to-rank is advantageous
• Good English skills (min. C1) round out your profile; German skills are a plus but not a requirement

Nice to Have

• Experience with LLM-based applications
• Knowledge in information retrieval, semantic search, recommender systems, or learning-to-rank

We Offer

Development and Responsibility

• Your commitment pays off – we promote your talent and offer opportunities to advance your career quickly
• Take ownership of your topics, bring in your own ideas, try out new approaches, and grow step by step in responsibility for productive search and ranking systems
• Benefit from internal training with specialized coaches and an annual budget for external further education

Team Spirit and Modern Work Environment

• Experience team spirit in everyday work and beyond – during lunch breaks, a round of table football, or after-work activities, and celebrate successes at regular company and team events
• Work in an inspiring environment with a modern office and high-quality equipment such as MacBooks and height-adjustable desks

Flexibility and Balance

• Fridays, working from home is optional – if you spend the day in the office, you earn additional vacation days beyond the 28 days
• Come to the office conveniently with your free Germany ticket or a subsidized company bike
• Enjoy a fresh, free lunch twice a week and use the opportunity for exchange with colleagues
• Stay active with our in-house sports courses or use our subsidized external sports offer, including EGYM Wellpass

Contact

Natja Scheffler

[email protected]

Please send us applications exclusively online via our application form.

Apply now