About Christian
• PhD in Computer Science, specialized in machine learning (ML) and artificial intelligence.
• 20+ years of professional experience as backend developer and software engineer, freelancing since 2006.
• Strong expertise in Python-based data processing and ML pipelines, including NumPy, Pandas, PyTorch, and scikit-learn.
• Extensive backend experience with SQL (especially PostgreSQL), RESTful APIs (including with FastAPI and Flask), and cloud-native systems (AWS, Supabase).
• Designed and deployed production-grade ML microservices for document classification, data extraction, and sentiment analysis.
• Familiar with containerized deployment and orchestration (Docker, Kubernetes, Helm).
• Worked in remote, agile teams on high-impact projects for major clients.
• Proficient in additional languages including Java, JavaScript, Haskell, and Ruby.
• Experienced in performance profiling and optimization, both in database and code-heavy contexts.
• Languages: German (native), English (near-native level).
• Available in Berlin and remote.
German
Native or bilingual
English
Fluent
Can work on-site
Berlin (up to 50km)
Experience
- Ragspero, a RAG (retrieval-augmented generation)AI chatbot frameworkIndependent open source project, scheduled for release in spring 2026SOFTWARE PUBLISHINGMarch 2025 - Today (1 year and 3 months)Berlin, Germany
- Processes PDF, HTML, and other file formats to build a custom knowledge base for domain-specific chatbots.
- Supports multiple languages, with English and German built-in.
- Built in Python based on Kotaemon, LangChain, FastAPI, Qdrant, and SentenceTransformer.
- Integrates Gemini, Ollama, or other pluggable LLMs.
- Runs locally or as a public web service.
- ACB StudioPostgreSQL backend developerSOFTWARE PUBLISHINGFebruary 2024 - November 2024 (10 months)Düsseldorf, Germany
- Rewrite of the mytischtennis.de website with an high-performance database-first backend written in PostgreSQL and PL/pgSQL.
- Creation of payment and order workflows integrating PayPal and PayOne as payment providers.
- Retrieval of data from external systems using Postgres caching for fast access times.
- T-Systems InternationalPython/Pandas developer and data scientistSOFTWARE PUBLISHINGApril 2023 - December 2023 (7 months)Frankfurt am Main, Germany
- Development of SPACE (Statistical Production and Compilation Environment), the new data analytics platform used by the European Central Bank (ECB).
- Integration of various data sources from banks and statistical authorities into the ECB’s new Pandas-based data analytics platform.
- Analysis and elimination of performance bottlenecks in the software.
- Porting of the whole SPACE software from Pandas 1.3 to 2.1.
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Education
- PhD in Computer ScienceFree University of Berlin2007Thesis title: An Incrementally Trainable Statistical Approach to Information Extraction. Thesis topic: Statistical extraction information extraction (IE) from weekly structured texts (HTML/XML) using incremental machine learning algorithms. Funded by a 3-year fellowship of the Berlin-Brandenburg Graduate School in Distributed Information Systems.
- Diplom Studies Computer ScienceTechnical University of Berlin2002Graduated as Diplom-Informatiker (Master of Science in Computer Science). Thesis title: A Toolkit for Caching and Prefetching in the Context of Web Application Platforms. Thesis topic: Using machine learning (Markov models) to predict upcoming web requests to allow faster response times.