About

AI engineer, full-stack engineer, and fractional CTO in Frankfurt, bridging engineering depth with commercial judgment.

I am an AI engineer, full-stack engineer, and fractional CTO based in Frankfurt am Main. For more than ten years I have built, led, stabilized, and scaled technology in European startups, from early product discovery to regulated SaaS platforms and post-acquisition transitions.

My work sits between engineering depth and commercial reality. I write code, shape architecture, build teams, reduce operational risk, and help founders and leadership teams turn technical decisions into business outcomes.

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What I do

  • Fractional and interim CTO work for startups, scaleups, and acquired platforms.
  • AI engineering for agentic workflows, RAG systems, LLM pipelines, voice systems, OCR, and document automation.
  • Full-stack product engineering across frontend, backend, APIs, data, infrastructure, and deployment.
  • Architecture, security, DevSecOps, observability, deployment process, and technical debt reduction.
  • Engineering team building, coaching, hiring, agile process, code review culture, and AI tool adoption.
  • Product and commercial translation for founders, product leaders, investors, and technical teams.

Experience in brief

I was CTO and co-founder at Digital Office 24, where we built a multi-tenant SaaS platform for multi-asset management, wealth management, accounting, tax, and banking in a regulated environment. I grew the engineering team from zero to more than ten people and established architecture, security, CI/CD, DevSecOps, and engineering process from the ground up.

I founded and sold 2markdown, a developer tool for converting web pages into structured Markdown for GenAI workflows.

At Aivy, formerly feel.yt, I moved from working student to CTO. We built on Google Cloud with Python and Flask, developed ETL pipelines and custom multi-label text classification, and pivoted the product toward machine learning for mood and atmosphere prediction.

As a fractional CTO and post-acquisition tech lead at Connect Earth, I helped stabilize an ESG compliance platform after acquisition. The work included technical assessment, observability, alerting, deployment process, latency improvements, codebase documentation, AI-tool coaching, and handover to the internal engineering leadership.

Selected systems and projects

CRMe
Open-source AI-native CRM with agentic capabilities, a custom AI layer, PostgreSQL, TypeScript, Next.js, and Go.

Hiro
Internet crawler and search engine with hybrid retrieval: pgvector semantic search, PostgreSQL full-text search, a Go crawler, Python embedding and search services, gRPC, HTMX, and Alpine.js.

Supasec
Autonomous security scanner for Supabase applications. It crawls pages and JavaScript bundles, extracts Supabase URLs, anon keys, and RPC calls, then checks PostgREST endpoints for exposed schema, RLS misconfiguration, and auth bypasses.

Financial scenario planner and MCP server
Conversational AI for wealth scenarios in real time. Users describe financial questions in natural language, while the system calculates, visualizes, and explains tradeoffs.

Banking transaction analysis and reconciliation
Two agent systems using the Tink API: document labelling with OCR and fuzzy matching, plus automated reconciliation.

Voice AI chatbot
Telegram voice interaction with Whisper STT, ElevenLabs TTS, a multi-LLM backend, and vector memory.

Technical focus

Python, Go, Rust/Tauri, TypeScript, Next.js, FastAPI, Flask, Docker, Terraform, GitHub Actions, PostgreSQL, pgvector, Supabase, n8n, Selenium, scikit-learn, scikit-multilearn, AWS, GCP, Azure, OpenTelemetry, OWASP, and DevSecOps.

AI and LLM work includes PydanticAI, LangChain, LangGraph, PocketFlow, OpenAI Agent SDK, Claude Agent SDK, MCP, RAG, hybrid retrieval, LLM evaluation, conversational AI, tool calling, Whisper, ElevenLabs, Mistral OCR, Tesseract, document extraction, and classification.

Education

MSc Computer Science, AI and Machine Learning, Philipps-Universität Marburg.
BSc Computer Science, Technische Hochschule Mittelhessen.

German native speaker. English near-native, C2.

References

When Christian came in, we had just acquired a platform our team did not build, with no senior technical leadership in place and incidents surfacing through customer complaints. Within 11 weeks he assessed the technology, defined a roadmap, and executed it. He stabilized production, reduced key-person risk, and built the clarity the team needed to operate independently. We went from post-acquisition risk mitigation to being positioned for growth. I would work with him again without hesitation.

Alexander Wilhelm Lempka, Founder & CEO, Connect Earth

Christian gave me and the team space to breathe, clarity, and confidence after complex M&A activity. He positioned us well for growth and delivered exactly what you want from fractional roles: lasting process and confidence improvements, not sticking plaster fixes.

David Higginson, Head of Product, Connect Earth