Freelancer profile translated to English.

Description

Java/Spring expert for performance optimization. 26 years of professional IT experience, 16 years Spring. I bring fresh perspectives to existing systems and deliver measurable improvements.

🔥 Results from previous projects

Latencies reduced by a factor of 10-20.
Batch processing accelerated by a factor of 5-180.
Memory footprint and build times halved.
Specific numbers for each project below.

🎯 How I support teams

Performance analysis and targeted optimization of existing systems.
Architecture reviews with concrete, actionable recommendations.
Technical documentation and knowledge transfer to the team.
Building monitoring and observability where transparency is currently lacking.

Tech Stack: Java, Spring Boot, PostgreSQL, Kafka, Spring Batch, Svelte, TypeScript, Docker

Hands-on with code, data-driven, results-oriented.

Complex legacy systems, performance bottlenecks, upcoming migrations – I bring the experience and methodology for these challenges.

Industry field of expertise

Languages

German
Native or bilingual
English
Conversational
Russian
Native or bilingual

Workplace preferences

Remote only

Primarily works remotely

Adesso Insurance Solutions
Senior Expert for Crisis Analysis & Realignment of Data Migration
SOFTWARE PUBLISHING
October 2025 - October 2025
Köln, Germany
Migration of InterRisk Data
IT Modernization at InterRisk: Migration of insurance data from 23 legacy systems into the in|sure Ecosphere. Target systems: Partner management, contract management, claims processing, payment processing, commission accounting.

Successes and Tasks:
Analysis of the existing migration framework "MigSuite"
Creation of an alternative concept based on Spring Batch, including management presentation (technical concept, 90% cost reduction, risk assessment)
Implementation of a production PoC (acceleration by a factor of 180):
– Staging: 50 minutes → 11 seconds
– Import: 225 minutes → 80 seconds
– Projected total runtime: from weeks to a few hours

Duration of engagement: 4 weeks

Technologies:
Backend: Java, Spring Boot, Spring Batch, JPA/Hibernate, WildFly
Databases: PostgreSQL
DevOps: Maven, Docker/Docker Compose, Liquibase
Java PostgreSQL performance-optimization Spring Batch JPA/Hibernate
adesso SE
Senior Software Engineer, Architect
BANKING AND INSURANCE
September 2025 - September 2025
Frankfurt am Main, Germany
ReTruSt – Rule-based CSV Data Processing
ReTruSt (Rule-based Transformation and Streaming) is a low-code platform for processing large amounts of CSV data in the banking sector. Rule definition via Google Blockly without programming knowledge. Microservice architecture with Java/Quarkus, PostgreSQL, Kafka, Keycloak. Target environment: Kubernetes.

Successes and Tasks:
Concurrency analysis: 10 anti-patterns identified and resolved, 4 of which were critical (Resource Leaks, Buffer Overflow, Lock Contention)
Performance optimization: JDBC batching, virtual threads – overall performance improved by a factor of 10
Build optimization: Gradle build time reduced from 10 to 2 minutes
Docker Compose optimization: Service dependencies corrected, memory footprint reduced (Redpanda 1GB→100MB, Keycloak 1GB→400MB), startup time accelerated by a factor of 5
Architecture analysis: Technical documentation with optimization suggestions
Alternative concept "WorkflowForge" developed: Plugin-based batch platform based on Spring Batch with capability system and scalable execution (local to cloud)

Duration of engagement: 4 weeks

Technologien:
Backend: Java, Quarkus, Apache Kafka, virtual threads, JDBC batching
Databases: PostgreSQL
DevOps: Gradle, Docker, Docker Compose, ELK Stack
Java Quarkus Apache Kafka PostgreSQL Docker
Eigenproduktion
Sci-Life.art – Health Portal with LP-based Nutrition Optimization
HEALTH AND WELLNESS
January 2024 - Today (2 years and 5 months)
Wiesbaden, Germany
Project Sci-Life.art – The Art of the Scientific Lifestyle

Health platform with a scientific approach: nutrition tracking, biomarker collection, and automated meal planning through linear optimization for disease prevention. 1.5 million+ foods, curated nutrient data.

Activities:
Domain modeling: 10 Bounded Contexts with DDD, Event Storming, Context Map
Import and harmonization of food databases: 500 curated, 8,000+ common foods, 1.5 million branded foods (USDA, CNF, SCF)
Knowledge Graph: Curated database with nutrient-disease relationships
LP-based nutrition optimization: 84 biochemical targets in 12 areas of cholesterol metabolism analyzed, constraints derived for linear optimization (Ojalgo)
Voice Input: PoC for C++ microservice with Speech-to-Text
Subscription model with feature tiers (Guest → Free → Basic → Premium)

Skills:
Backend: Java, Spring Boot, Spring Security, JPA/Hibernate, Spring Data
Frontend: TypeScript, Svelte
Databases: Postgres, Flyway
Algorithms: Linear Optimization (Ojalgo)
DevOps: Maven, Git, GitHub Actions, Docker, Vite
Testing: JUnit, SonarQube, Vitest
Java Spring Boot Svelte PostgreSQL TypeScript