JUnit Experts in Berlin

• Developed and deployed microservices in Kotlin and Spring Boot, integrated AWS Secrets Manager to secure credentials and decreased network calls using Spring cache.
• Refactored Kafka consumer using Spring Kafka with semaphore-based backpressure to cap records and keep heap memory stable under spikes; switched to batch upserts to cut down on database invocations; added Testcontainers integration tests for Kafka and database to pave the way for future changes.
• Automated the financial reconciliation workflow in Spring Boot (Kotlin) using Spring Scheduler, transactional boundaries, JPA/Hibernate on MySQL, and Flyway migrations, saving the accounts team 16+ hours per week.
• Designed and dockerized payments end-to-end test framework in Robot (Python) with reusable keyword libraries and profiles; integrated with GitLab CI (JaCoCo XML and HTML reports) to accelerate releases and lift code coverage to 80%.
• Implemented end-to-end observability on Datadog by instrumenting services with Datadog APM, correlating metrics and logs, provisioning dashboards, and creating monitors with burn-rate alerts and anomalies to harden reliability and give stakeholders clear visibility.

• IT training in theory and practice for IT specialists in application development and system integration

• Context: Healthcare and laboratory teams required faster document analysis, treatment-planning support, and reliable AI workflows for MR/VR-assisted operations.
• Contribution: Built the AI healthcare platform, model/agent workflows, VR-glasses deployment platform, REST APIs, Next.js/React interfaces, and CI/CD pipelines.
• Impact: Delivered a production-ready AI product foundation that improved clinical document review, supported laboratory automation, and made VR fleet deployment manageable across environments.

Tech: TypeScript, Next.js, Node.js, React, Java, Spring Boot, Python, PyTorch, TensorFlow, Docker, PostgreSQL, OpenAPI, GitLab, GitHub Actions.

• Overhaul of the entire design and implementation of new UI/UX aspects using React
• Planning of the software architecture and structuring of the project for long-term scalability using Git for version control

• Bootstrapping a CloudOps team and building a multi-cloud provider backend for a low-code Internal Developer Platform (IDP) with env zero

• Introducing user story mapping, ADRs, milestones, and backlog management

• Designing and developing core APIs, setting up CI/CD pipelines, OpenTofu/Terraform scripts

• Representing and communicating the team with third-party stakeholders (e.g. env zero)

• (Cross-)team coaching on DevOps, software design, Terraform, Golang, and agile practices

• Single-handedly executing end-to-end legacy system migration to modern stack, working autonomously with minimal supervision
• Converting stakeholder resistance into buy-in through regular demos and feedback sessions with initially skeptical internal teams
• Proactively identifying improvements to common libraries beyond project scope

• Creation, maintenance and hardening of Kubernetes clusters employing Ansible and ArgoCD
• Keywords: Ansible, AWX, Kubernetes, NetApp, Prometheus, CI/CD ArgoCD, SSO, Fluent-bit, HAProxy, Calico, Keycloak, oauth2-proxy, SealedSecrets, kubeseal, Aqua kube-bench, CIS-Benchmarks, Aqua Trivy operator

• Subject matter expert for the client on modeling and developing Camunda BPMN 2.0
• Development of new features and APIs, and coordination of tasks
• Design and development of RESTful APIs with Swagger (code first)
• Creation of target designs, high-level concepts, and requirement specifications
• Analysis and evaluation of alternative solution approaches
• Integration of external IT systems (ANUBIS, SES, ZPS) via Google GCP Pub/Sub and RESTful web services
• Pair programming, code reviews, and collaboration with API product owners
• Consulting on transforming legacy BPMN workflows and configuring Camunda BPM
• BPMN and DMN modeling and implementation in short iterations
• Operational support, bug fixing, and knowledge documentation
• Use of TDD, static code analysis with SonarQube, and integration tests
• Automation of test cases in Java and analysis of stack traces/logs on GCP-PROD
• Identification and execution of test data and documentation of test results

• Project 1: Multi-Tenant SaaS Platform: Data Integration & Pricing Management
• Objective: New development of ELT pipeline (replacement for Java 6 legacy), integration of heterogeneous source systems (CSV, Excel, Email, external DBs), event-sourcing for complete auditability, multi-tenant architecture for tenant-capable data processing
• Challenge: Processing millions of records daily, audit compliance, data isolation between different tenants
• Solution: Stakeholder workshops for requirements analysis, event-driven architecture with Axon Framework and Apache Kafka, AWS services (EC2, S3, Lambda, SQS, API Gateway) for cloud integration, PostgreSQL with tenant-specific schemas for multi-tenant data isolation, REST API design with Spring Boot for external system integrations, comprehensive testing strategy (JUnit, Spring Test, Postman, PACT, ArchUnit)
• Results: ELT performance improved from 30+ min to 1-5 min; 2-3 hours daily saved through workflow automation; 10-20 hours/week saved through event-sourcing auditability; 100% audit compliance; secure multi-tenant data isolation for 10+ tenants
• Project 2: Multi-tenant CRM System Modernization
• Objective: Migration of CRM system (20+ years PHP/MySQL) to Java microservices, Domain-Driven Design implementation, establishment of Test-Driven Development, multi-tenant-capable SaaS architecture for multiple customer tenants
• Challenge: Remodeling complex business logic, no existing test culture, scalable tenant management with data isolation
• Solution: Comprehensive testing strategy (JUnit, Spring Test, Postman, PACT, ArchUnit), multi-tenant architecture with tenant-specific databases, REST API design with Spring Boot for cross-tenant integration, Kubernetes and Docker for container orchestration
• Results: 2× performance improvement; deployment time reduced from 40+ min to 5-7 min; migration without production outages; scalable multi-tenant solution for 15+ customer tenants
• Technologies: Java, Spring Boot 3.x, Angular, Apache Kafka, AWS (EC2, S3, Lambda, SQS, API Gateway), PostgreSQL, Axon Framework, Kubernetes, Docker, GitLab CI, REST API

• Developed a SolidJS frontend UI for a spectrometric water analysis system on an ARM-based embedded Linux platform
• Prototyped UI in TypeScript React/Nx with LitElements and MQTT integration
• Built production UI using SolidJS, SUID, i18next, Ajv, MQTT.js, C3.js
• Refined requirements with UX team and water analysis system engineers
• Defined and documented system architecture, MQTT message formats, frontend architecture, and development setup
• Set up frontend system from scratch, implemented domain-oriented type system, UI components, and application state
• Managed MQTT pub/sub services and schema-based message validation in frontend
• Coached two junior frontend developers
• Worked in an agile remote team using JIRA, Git, and Bitbucket

• Provide the Price Listing Service Team Price for all cars and vans in different markets
• Adjust market-specific requirements like taxes, government subsidies, campaigns
• Import, synchronize and store new prices for all new and existing cars in Redis datastore
• Support our product and handle on-call duties
• Daily operations, developing new features, bug fixing
• Pair programming, code reviews, mob programming
• Develop POCs for new ideas
• Maintain and extend the backend
• DevOps tasks
• Perform Kubernetes updates
• Adjust and further develop Kubernetes resources
• Develop and customize Helm charts
• Adjust and update ArgoCD
• Maintain, adjust and further develop CI/CD pipelines

• Developed high-performance APIs for SDK backend on JavaEE Web, iOS, and Android, improving application performance and scalability by 30%.
• Led system design, tech stack planning, and development, ensuring 98% uptime with strong code quality and automated tests.
• Implemented CI/CD pipelines with Jenkins and GitHub Actions, reducing release cycle time by 40%.
• Deployed cloud-native applications on AWS EC2 instances, ensuring 99% uptime and optimized performance.
• Delivered clean code with full unit, component, and integration test coverage, reducing defects by 25%.
• Collaborated across engineering, QA, and product teams to deliver secure, reliable solutions.
• Mentored team members, increased development efficiency by 20%, automated routine tasks, and contributed to hiring, growing team capacity by 15%.

• Developed a Proof of Concept for distributed tracing using OpenTelemetry within a microservices architecture, enhancing system observability and reducing mean-time-to-resolution for issues.
• Built and maintained backend services using Java and Spring Boot, ensuring high reliability and performance for payment transaction workflows.
• Implemented comprehensive automated testing with JUnit and Mockito, achieving 95% test coverage to ensure code quality and maintainability.
• Gained insight into payment transaction workflows, validating end-to-end system reliability and gaining domain knowledge in financial processes.
• Tech used: Java, Spring Boot, Microservices, REST API, Kafka, Grafana, Datadog, Docker, MongoDB

• Built a portfolio website using Vue 3 implementing dynamic pages responsive UI components.
• Integrated OpenAI ChatGPT API for interactive AI content generation.
• Handled API requests and media management via Cloudflare, enabling efficient communication and asset delivery.
• Vue.js
• Vuetify
• C++, WPF
• Debian
• Matlab
• MySQL
• PostgreSQL
• Tailwind CSS
• Cloudflare Workers
• GitHub Actions
• Node.js