Staff Data Engineer - Ofer Kulka | Data & AI Consulting - Frankfurt am Main, Germany
(2024-02)
AI / LLM portfolio development:
- Designed and deployed an end-to-end AI-driven underwriting system using Medallion architecture and the Ontology (Palantir Foundry). Benchmarked time to credit memo generation was reduced by 85%.
- Built a hybrid Retrieval-Augmented Generation (RAG) architecture using Python, FastAPI, LangChain, Redis, PGvectorscale, and Pydantic AI, integrating 10+ research-papers as data sources. The system is able to scale to hundreds of documents, adding Redis reduced query retrieval latency by 93% within my development environment.
- Developed LLM applications with guardrails, structured outputs, retry logic, and observability, improving system reliability and reducing operational errors in AI inference workflows.
- Implemented schema validation and response governance, enabling controlled LLM outputs, confidence scoring, and improved robustness of generative AI pipelines.
- Optimized data processing and analytical pipelines using Python and DuckDB, reducing iteration cycles and accelerating the transition from experimental prototypes to production deployment.
- Implemented secure API architecture and AI application security controls, including rate limiting, endpoint isolation, security headers, and secrets management, protecting systems from API abuse and unauthorized access.
Staff Data Engineer - BO1 AG (Fintech / Payments)
(2024-05 - 2025-05)
Client engagement
- Led the greenfield design and implementation of a cloud-based analytics platform on Azure (ADLS, Azure Data Factory, Power BI), defining data architecture, ingestion standards, and governance.
- Designed the data lake structure, schema, file format and ingestion frequency, establishing the bronze layer and defining the ingestion and retention policies of data across the organization.
- Built an MVP analytics stack (ADLS, Power BI, DAX, Power Query) delivering operational dashboards and KPI tracking across 10+ business metrics, providing leadership with financial and operational visibility of the business.
- Designed and implemented mobile event tracking using Amplitude (iOS & Android) to facilitate product and customer analytics across mobile, funnel analysis, segmentation, and drop-off analysis across the full customer lifecycle.
- Defined and implemented a North Star metric framework, linking growth drivers, experiments, and product initiatives.
- Collaborated with Engineering and QA teams to generate and validate product telemetry and test datasets, aligning expected results vs. actual data during early product releases to enable reliable analytics.
Career Break
(2023-07 - 2024-02)
Head of Business Insights (Data Architect & Analytics Engineer) - Qonto (Penta GmbH) - Berlin, Germany
(2019-12 - 2023-06)
- Led the data strategy, roadmap, and architecture for the organization, designing and deploying a company-wide data platform on AWS (DMS, SQS, S3), Airflow, dbt, and Snowflake.
- Built and managed the Business Insights team, responsible for hiring, mentoring, and delivering analytics solutions across product, marketing, and operations.
- Implemented scalable ELT pipelines and data models for revenue, gross margin, cohort, and funnel analyses across 5+ business domains, enabling reliable data foundations for decision-making.
- Established DataOps and engineering best practices (CI/CD, version control, data testing), improving data reliability and reducing analytics incidents by 30%.
- Partnered directly with C-level executives, product leadership, and department heads to define data requirements and align analytics initiatives with company strategy.
- Delivered actionable insights through cohort analysis, gross margin analytics, and funnel optimization, driving improvements in customer retention, marketing cost efficiency, pricing strategy, and onboarding conversion.
Staff Data Engineer - Solaris Group - Berlin, Germany
(2016-11 - 2019-06)
- Promoted to Team Lead from BI Analyst, maintaining a hands-on role while leading 3+ Data Analysts.
- Designed and implemented a data warehouse architecture, integrating 20+ financial data sources and 80+ tables to centralize analytics across transactions, card payments, lending, credit scores, KYC, and account data.
- Built and maintained 12+ batch ETL pipelines using Python, SQL, and Jenkins, supporting daily ingestion and transformation of financial datasets including transaction, payment, and credit data.
- Owned the end-to-end architecture design, data modeling, and deployment of the data platform, working with product owners to define data contracts and data ownership standards for source systems.
- Optimized SQL queries, ETL pipelines, and reporting workflows, significantly improving dashboard refresh times, query performance, and data processing efficiency across analytics systems.
- Developed and automated business-critical reporting pipelines and invoicing workflows, reducing manual workload by 90% while improving reporting accuracy and financial monitoring capabilities.
- Led the design and implementation of an automated AML transaction monitoring system, enabling scalable monitoring of financial transactions and strengthening compliance analytics.
Business Intelligence Analyst - OptioPay - Berlin, Germany
(2016-05 - 2016-08)
- Automated daily business performance reporting by building ETL pipelines using Python, SQL, and Jenkins.
- Built interactive Power BI dashboards used daily by product, finance, and technology teams, tracking key KPIs.
- Compiled and analyzed operational datasets using SQL queries and reporting pipelines, enabling teams to monitor business performance and identify emerging customer and product trends.
- Conducted exploratory data analysis and market basket analysis using R, identifying customer behavior patterns to support product and marketing insights.
